Carbon 14

Abstract By fuel combustion man has added about 150,000 million tons of carbon dioxide to the air during the past half century. The author estimates from the best available data that approximately three quarters of this has remained in the atmosphere. The radiation absorption coefficients of carbon dioxide and water vapour are used to show the effect of carbon dioxide on “sky radiation.” From this the increase in mean temperature, due to the artificial production of carbon dioxide, is estimated to be at the rate of 0.003°C. per year at the present time. The temperature observations a t zoo meteorological stations are used to show that world temperatures have actually increased at an average rate of 0.005°C. per year during the past half century.

@article{doi101002qj49706427503,
    author = "Callendar, G. S.",
    title = "The artificial production of carbon dioxide and its influence on temperature",
    year = "1938",
    journal = "Quarterly Journal of the Royal Meteorological Society",
    abstract = "Abstract By fuel combustion man has added about 150,000 million tons of carbon dioxide to the air during the past half century. The author estimates from the best available data that approximately three quarters of this has remained in the atmosphere. The radiation absorption coefficients of carbon dioxide and water vapour are used to show the effect of carbon dioxide on “sky radiation.” From this the increase in mean temperature, due to the artificial production of carbon dioxide, is estimated to be at the rate of 0.003°C. per year at the present time. The temperature observations a t zoo meteorological stations are used to show that world temperatures have actually increased at an average rate of 0.005°C. per year during the past half century.",
    url = "https://doi.org/10.1002/qj.49706427503",
    doi = "10.1002/qj.49706427503",
    openalex = "W2006447055",
    references = "openalexw375151676"
}

Steady-state equations governing the transfer and distribution of a radioactive isotope between its various exchange reservoirs are applied to the natural distribution of carbon 14. The radiocarbon enrichment or depletion in each reservoir, relative to the hypothetical state in which mixing is infinitely faster than the decay rate, is evaluated as a quantitative function of the exchange rates between the reservoirs. From the observed distribution of C 12, C 13, and C 14 in the atmosphere, biosphere, and sea, and from the estimated production rate of C 14 by cosmic rays, the residence time of a carbon dioxide molecule in the atmosphere, before entering the sea, is found to be between four and ten years. The atmospheric residence time may also be evaluated, independently of the estimated C 14 production rate, by considering the functional dependence of the C 14 concentration in the oceanic mixed layer on the residence times in the atmosphere and the deep sea. This second method of evaluation also leads to an atmospheric residence time of about seven years. The average annual exchange flux of carbon dioxide into the sea is thus about 2 times 10 −2 moles per square centimeter of sea surface. The average residence time of carbon dioxide in the deep sea is estimated as probably not more than about 500 years. DOI: 10.1111/j.2153-3490.1957.tb01848.x

@article{doi101111j215334901957tb01848x,
    author = "Craig, Harmon",
    title = "The Natural Distribution of Radiocarbon and the Exchange Time of Carbon Dioxide Between Atmosphere and Sea",
    year = "1957",
    journal = "Tellus",
    abstract = "Steady-state equations governing the transfer and distribution of a radioactive isotope between its various exchange reservoirs are applied to the natural distribution of carbon 14. The radiocarbon enrichment or depletion in each reservoir, relative to the hypothetical state in which mixing is infinitely faster than the decay rate, is evaluated as a quantitative function of the exchange rates between the reservoirs. From the observed distribution of C 12, C 13, and C 14 in the atmosphere, biosphere, and sea, and from the estimated production rate of C 14 by cosmic rays, the residence time of a carbon dioxide molecule in the atmosphere, before entering the sea, is found to be between four and ten years. The atmospheric residence time may also be evaluated, independently of the estimated C 14 production rate, by considering the functional dependence of the C 14 concentration in the oceanic mixed layer on the residence times in the atmosphere and the deep sea. This second method of evaluation also leads to an atmospheric residence time of about seven years. The average annual exchange flux of carbon dioxide into the sea is thus about 2 times 10 −2 moles per square centimeter of sea surface. The average residence time of carbon dioxide in the deep sea is estimated as probably not more than about 500 years. DOI: 10.1111/j.2153-3490.1957.tb01848.x",
    url = "https://doi.org/10.1111/j.2153-3490.1957.tb01848.x",
    doi = "10.1111/j.2153-3490.1957.tb01848.x",
    openalex = "W2023859923"
}

From a comparison of C14/C12 and C13/C12 ratios in wood and in marine material and from a slight decrease of the C14 concentration in terrestrial plants over the past 50 years it can be concluded that the average lifetime of a CO2 molecule in the atmosphere before it is dissolved into the sea is of the order of 10 years. This means that most of the CO2 released by artificial fuel combustion since the beginning of the industrial revolution must have been absorbed by the oceans. The increase of atmospheric CO2 from this cause is at present small but may become significant during future decades if industrial fuel combustion continues to rise exponentially. Present data on the total amount of CO2 in the atmosphere, on the rates and mechanisms of exchange, and on possible fluctuations in terrestrial and marine organic carbon, are inadequate for accurate measurement of future changes in atmospheric CO2. An opportunity exists during the International Geophysical Year to obtain much of the necessary information.

@article{doi103402tellusav9i19075,
    author = "Revelle, Roger and Sueß, Hans E.",
    title = "Carbon Dioxide Exchange Between Atmosphere and Ocean and the Question of an Increase of Atmospheric CO 2 during the Past Decades",
    year = "1957",
    journal = "Tellus A Dynamic Meteorology and Oceanography",
    abstract = "From a comparison of C14/C12 and C13/C12 ratios in wood and in marine material and from a slight decrease of the C14 concentration in terrestrial plants over the past 50 years it can be concluded that the average lifetime of a CO2 molecule in the atmosphere before it is dissolved into the sea is of the order of 10 years. This means that most of the CO2 released by artificial fuel combustion since the beginning of the industrial revolution must have been absorbed by the oceans. The increase of atmospheric CO2 from this cause is at present small but may become significant during future decades if industrial fuel combustion continues to rise exponentially. Present data on the total amount of CO2 in the atmosphere, on the rates and mechanisms of exchange, and on possible fluctuations in terrestrial and marine organic carbon, are inadequate for accurate measurement of future changes in atmospheric CO2. An opportunity exists during the International Geophysical Year to obtain much of the necessary information.",
    url = "https://doi.org/10.3402/tellusa.v9i1.9075",
    doi = "10.3402/tellusa.v9i1.9075",
    openalex = "W2073378033",
    references = "doi101002qj49706427503, doi101126science1223166415a, doi101130001676061951621111ghosw20co2"
}

About three years ago a laboratory was set up in Pisa for the study of geologic and paleontologic problems with the help of modern nuclear techniques. The two main items of the first program were the construction of a mass spectrometer for paleotemperature measurements and of a carbon-14 dating apparatus.

@article{doi101017s0033822200020415,
    author = "Ferrara, G. and Reinharz, M. and Tongiorgi, E.",
    title = "Carbon-14 Dating in Pisa",
    year = "1959",
    journal = "Radiocarbon",
    abstract = "About three years ago a laboratory was set up in Pisa for the study of geologic and paleontologic problems with the help of modern nuclear techniques. The two main items of the first program were the construction of a mass spectrometer for paleotemperature measurements and of a carbon-14 dating apparatus.",
    url = "https://www.cambridge.org/core/services/aop-cambridge-core/content/view/129A389C338DAE48D94216DAE95BC880/S0033822200020415a.pdf/div-class-title-carbon-14-dating-in-pisa-div.pdf",
    doi = "10.1017/S0033822200020415",
    is_oa = "true",
    pages = "103-110",
    semanticscholar_citation_count = "19",
    semanticscholar_id = "5b137469d01e408dd002a643c08cf60d582ac3dd",
    volume = "1"
}

In contrast to previous radiocarbon measurement lists, this list contains only known-age samples, most of which formed during the past ten years. The measurements were made largely in order to gain an understanding of the distribution of radiocarbon within the dynamic carbon reservoir both today and at times in the past. Since all materials forming in this reservoir today do not have the same C 14 /C 12 ratio, such an understanding is necessary in order to arrive at the most accurate possible estimate of the age of samples submitted for dating. This is particularly important when high accuracy (i.e., <100 years error) is required on subaerially grown samples and also when attempting to extend the method to samples which formed in reservoirs other than the atmosphere (for example, the ocean and freshwater systems).

@article{doi101017s0033822200020427,
    author = "Broecker, Wallace S. and Olson, Edwin A.",
    title = "Lamont Radiocarbon Measurements VI",
    year = "1959",
    journal = "Radiocarbon",
    abstract = "In contrast to previous radiocarbon measurement lists, this list contains only known-age samples, most of which formed during the past ten years. The measurements were made largely in order to gain an understanding of the distribution of radiocarbon within the dynamic carbon reservoir both today and at times in the past. Since all materials forming in this reservoir today do not have the same C 14 /C 12 ratio, such an understanding is necessary in order to arrive at the most accurate possible estimate of the age of samples submitted for dating. This is particularly important when high accuracy (i.e., <100 years error) is required on subaerially grown samples and also when attempting to extend the method to samples which formed in reservoirs other than the atmosphere (for example, the ocean and freshwater systems).",
    url = "https://doi.org/10.1017/s0033822200020427",
    doi = "10.1017/s0033822200020427",
    openalex = "W2265264778"
}

By the use of suitable chemical and radiometric techniques the natural radiocarbon concentration in the dissolved bicarbonate of 135 samples representing the major water masses of the Atlantic Ocean has been determined with a precision ranging from 0.5 to 1.3 per cent. Whereas the results from a given water mass exhibit a standard deviation only slightly exceeding that predicted from the experimental error alone, measurable differences exist between the major water masses, the total range in C14/C12 ratio being about 10 per cent. Corrections for the bomb-produced C14 effect and the industrial CO2 effect have been applied where necessary. The surface water C14/C12 ratios show a progressive increase from south to north, ranging from 120 per mil lower than the preindustrial atmospheric value in the Antarctic to 50 per mil lower in the North Atlantic. Deep water masses originating in the high latitudes of the southern hemisphere have consistently lower C14/C12 ratios than those originating in the high latitudes of the northern hemisphere. A layer of water of high C14/C12 ratio found at depths between 1200 and 2400 meters in the western North Atlantic may well represent a wedge of young water penetrating the older North Atlantic deep water. Bottom water in the eastern basin of the North Atlantic has a 20 per mil lower C14/C12 ratio than the corresponding water in the western basin. According to a steady-state circulation model, most of the water below 600 meters in the North Atlantic remains at depth for an average of 650 years. Corresponding residence times for water masses of Antarctic origin are less than 350 years. A circulation model explaining the prominent features of the C14 distributions in the atmosphere-ocean system is based on a south to north transport of water along the surface of the Atlantic Ocean, with a return flow at depth. The Atlantic and Pacific communicate through the Antarctic. On the basis of this model, despite the lower ΔC14 values, the mean residence times of water in the deep reservoirs of the Pacific may not exceed those for the deep Atlantic by more than 30 per cent. Although results of C14 analyses on tree rings suggest that the oceans are reasonably close to steady state, the possibility of nonsteady-state circulation must be considered. It is shown that the present C14 distribution in the oceans could be achieved through the storage of C14 in the atmosphere and surface oceans during a relatively short period of greatly restricted bottom water formation. If nonequilibrium effects are important the residence times computed from the steady-state model could be considerably in error.

@article{doi101029jz065i009p02903,
    author = "Broecker, Wallace S. and Gerard, Robert D. and Ewing, Maurice and Heezen, Bruce C.",
    title = "Natural radiocarbon in the Atlantic Ocean",
    year = "1960",
    journal = "Journal of Geophysical Research Atmospheres",
    abstract = "By the use of suitable chemical and radiometric techniques the natural radiocarbon concentration in the dissolved bicarbonate of 135 samples representing the major water masses of the Atlantic Ocean has been determined with a precision ranging from 0.5 to 1.3 per cent. Whereas the results from a given water mass exhibit a standard deviation only slightly exceeding that predicted from the experimental error alone, measurable differences exist between the major water masses, the total range in C14/C12 ratio being about 10 per cent. Corrections for the bomb-produced C14 effect and the industrial CO2 effect have been applied where necessary. The surface water C14/C12 ratios show a progressive increase from south to north, ranging from 120 per mil lower than the preindustrial atmospheric value in the Antarctic to 50 per mil lower in the North Atlantic. Deep water masses originating in the high latitudes of the southern hemisphere have consistently lower C14/C12 ratios than those originating in the high latitudes of the northern hemisphere. A layer of water of high C14/C12 ratio found at depths between 1200 and 2400 meters in the western North Atlantic may well represent a wedge of young water penetrating the older North Atlantic deep water. Bottom water in the eastern basin of the North Atlantic has a 20 per mil lower C14/C12 ratio than the corresponding water in the western basin. According to a steady-state circulation model, most of the water below 600 meters in the North Atlantic remains at depth for an average of 650 years. Corresponding residence times for water masses of Antarctic origin are less than 350 years. A circulation model explaining the prominent features of the C14 distributions in the atmosphere-ocean system is based on a south to north transport of water along the surface of the Atlantic Ocean, with a return flow at depth. The Atlantic and Pacific communicate through the Antarctic. On the basis of this model, despite the lower ΔC14 values, the mean residence times of water in the deep reservoirs of the Pacific may not exceed those for the deep Atlantic by more than 30 per cent. Although results of C14 analyses on tree rings suggest that the oceans are reasonably close to steady state, the possibility of nonsteady-state circulation must be considered. It is shown that the present C14 distribution in the oceans could be achieved through the storage of C14 in the atmosphere and surface oceans during a relatively short period of greatly restricted bottom water formation. If nonequilibrium effects are important the residence times computed from the steady-state model could be considerably in error.",
    url = "https://doi.org/10.1029/jz065i009p02903",
    doi = "10.1029/jz065i009p02903",
    openalex = "W2019984710",
    references = "doi1010160016703753900015, doi101016014663135690048x, doi101016s0146629158800144, doi101017s0033822200020427, doi1010381791183a0, doi101111j215334901957tb01848x, doi101111j215334901957tb01849x, doi101126science1223166415a, doi103402tellusav9i19075, openalexw3216360278"
}

Samples are analyzed for natural radiocarbon content by a total synthesis of benzene from their organic constituents. The benzene is employed as the solvent in a liquid scintillation counter. The instrument used permits 15 grams of carbon to be counted with an efficiency of 40 percent and a background of 13 counts per minute.

@article{doi101126science1323428668,
    author = "Tamers, Murry A.",
    title = "Carbon-14 Dating with the Liquid Scintillation Counter: Total Synthesis of the Benzene Solvent",
    year = "1960",
    journal = "Science",
    abstract = "Samples are analyzed for natural radiocarbon content by a total synthesis of benzene from their organic constituents. The benzene is employed as the solvent in a liquid scintillation counter. The instrument used permits 15 grams of carbon to be counted with an efficiency of 40 percent and a background of 13 counts per minute.",
    url = "https://www.semanticscholar.org/paper/48076a222999ae1678e0231dd8d1a481ceb06298",
    doi = "10.1126/science.132.3428.668",
    is_oa = "true",
    number = "3428",
    pages = "668-669",
    semanticscholar_citation_count = "32",
    semanticscholar_id = "48076a222999ae1678e0231dd8d1a481ceb06298",
    volume = "132"
}

A systematic variation with season and latitude in the concentration and isotopic abundance of atmospheric carbon dioxide has been found in the northern hemisphere. In Antarctica, however, a small but persistent increase in concentration has been found. Possible causes for these variations are discussed.

@article{doi103402tellusav12i29366,
    author = "Keeling, Charles D.",
    title = "The Concentration and Isotopic Abundances of Carbon Dioxide in the Atmosphere",
    year = "1960",
    journal = "Tellus A Dynamic Meteorology and Oceanography",
    abstract = "A systematic variation with season and latitude in the concentration and isotopic abundance of atmospheric carbon dioxide has been found in the northern hemisphere. In Antarctica, however, a small but persistent increase in concentration has been found. Possible causes for these variations are discussed.",
    url = "https://doi.org/10.3402/tellusa.v12i2.9366",
    doi = "10.3402/tellusa.v12i2.9366",
    openalex = "W2045577557"
}

Almost all radiocarbon measurements reported in the following list have been made with the same equipment and method used for the measurements reported in our previous work (Pisa-I). The sample used as contemporary standard for these samples is also charcoal obtained from Arbutus unedo wood grown near Pisa between 1948 and 1956. The value obtained from this standard has also been used for shell samples.

@article{doi101017s0033822200020889,
    author = "Ferrara, G. and Fornaca, Rinaldi G and Tongiorgi, E.",
    title = "Carbon-14 Dating in Pisa—II",
    year = "1961",
    journal = "Radiocarbon",
    abstract = "Almost all radiocarbon measurements reported in the following list have been made with the same equipment and method used for the measurements reported in our previous work (Pisa-I). The sample used as contemporary standard for these samples is also charcoal obtained from Arbutus unedo wood grown near Pisa between 1948 and 1956. The value obtained from this standard has also been used for shell samples.",
    url = "https://doi.org/10.1017/s0033822200020889",
    doi = "10.1017/S0033822200020889",
    is_oa = "true",
    pages = "99-104",
    semanticscholar_citation_count = "23",
    semanticscholar_id = "3b156e8cc5b45b564441d570669fc477b12765dd",
    volume = "3"
}

@article{crossref1962carbon14,
    title = "Carbon-14 Dates",
    year = "1962",
    journal = "Current Anthropology",
    url = "https://doi.org/10.1086/200281",
    doi = "10.1086/200281",
    number = "2",
    pages = "218-218",
    volume = "3"
}

@article{doi101038195943a0,
    author = "Godwin, H.",
    title = "Radiocarbon Dating: Fifth International Conference",
    year = "1962",
    journal = "Nature",
    url = "https://doi.org/10.1038/195943a0",
    doi = "10.1038/195943a0",
    openalex = "W1978151335"
}

Representative data on the variations of carbon dioxide in the atmosphere are presented. The data reveal a presumably natural source in the tropical oceanic areas and the industrial source of midlatitudes. Using a simple model of large-scale exchange, the meridional eddy exchange coefficient is computed to be about 3×1010 cm2 sec−1, and the meridional transport from tropical to north polar areas is computed to be about 2×1010 metric tons of carbon dioxide per year. An analysis of the seasonal variation shows that land vegetation north of 45°N is responsible for a net consumption of carbon dioxide of about 1.5×1010 tons during the vegetation period in summer. It is concluded that carbon dioxide is an excellent tracer for the study of atmospheric mixing processes. More data are needed, however, to make full use of it.

@article{doi101029jz068i013p03899,
    author = "Bolin, B. and Keeling, Charles D.",
    title = "Large-scale atmospheric mixing as deduced from the seasonal and meridional variations of carbon dioxide",
    year = "1963",
    journal = "Journal of Geophysical Research Atmospheres",
    abstract = "Representative data on the variations of carbon dioxide in the atmosphere are presented. The data reveal a presumably natural source in the tropical oceanic areas and the industrial source of midlatitudes. Using a simple model of large-scale exchange, the meridional eddy exchange coefficient is computed to be about 3×1010 cm2 sec−1, and the meridional transport from tropical to north polar areas is computed to be about 2×1010 metric tons of carbon dioxide per year. An analysis of the seasonal variation shows that land vegetation north of 45°N is responsible for a net consumption of carbon dioxide of about 1.5×1010 tons during the vegetation period in summer. It is concluded that carbon dioxide is an excellent tracer for the study of atmospheric mixing processes. More data are needed, however, to make full use of it.",
    url = "https://doi.org/10.1029/jz068i013p03899",
    doi = "10.1029/jz068i013p03899",
    openalex = "W2165690301"
}

@misc{kieth1963radiocarbon3,
    author = "Kieth, M. S. and Anderson, G. M",
    title = "Radiocarbon dating",
    year = "1963",
    howpublished = "fictitious results with mollusk shells: Science, v. 141, p. 634",
    note = "talkorigins\_source = {true}; raw\_reference = {Kieth, M. S., and Anderson, G. M., 1963, Radiocarbon dating: fictitious results with mollusk shells: Science, v. 141, p. 634.}"
}

@article{lingenfelter1963production4,
    author = "Lingenfelter, R. E",
    title = "Production of carbon 14 by cosmic ray neutrons",
    year = "1963",
    journal = "Reviews of Geophysics, v. 1, no. 1, p. 35-55",
    note = "talkorigins\_source = {true}; raw\_reference = {Lingenfelter, R. E., 1963, Production of carbon 14 by cosmic ray neutrons: Reviews of Geophysics, v. 1, no. 1, p. 35-55.}"
}

A proportional counting system for radiocarbon dating and precedures for producing carbon dioxide are described in this paper. The center counter was filled with carbon dioxide at one atmospheric pressure. The total background is 5.87f0.01 cpm. The value of 95% of the NBS contemporary standard for carbon-14 dating was taken as a standard of dating work.

@article{s2d3444b7a874ee3d2d85cb8760f849d79e34d2487,
    author = "Hsu, Y. and Huang, Chia-Yi and Lin, Song-Yun and Hsu, Y. and Chou, M. and Lu, Shih-Chong and Tai, Y.",
    title = "Low Background Counter for Carbon-14 Dating",
    year = "1965",
    journal = "Chinese Journal of Physics",
    abstract = "A proportional counting system for radiocarbon dating and precedures for producing carbon dioxide are described in this paper. The center counter was filled with carbon dioxide at one atmospheric pressure. The total background is 5.87f0.01 cpm. The value of 95\% of the NBS contemporary standard for carbon-14 dating was taken as a standard of dating work.",
    url = "https://www.semanticscholar.org/paper/d3444b7a874ee3d2d85cb8760f849d79e34d2487",
    is_oa = "true",
    openalex = "W1552833781",
    semanticscholar_citation_count = "6",
    semanticscholar_id = "d3444b7a874ee3d2d85cb8760f849d79e34d2487"
}

@misc{whitelaw1968radiocarbon9,
    author = "Whitelaw, R. L",
    title = "Radiocarbon confirms biblical creation",
    year = "1968",
    howpublished = "Creation Research Society Quarterly, v. 5, p. 80",
    note = "talkorigins\_source = {true}; raw\_reference = {Whitelaw, R. L., 1968, Radiocarbon confirms biblical creation: Creation Research Society Quarterly, v. 5, p. 80.}"
}

@article{doi101029jc074i023p05491,
    author = "Craig, H.",
    title = "Abyssal carbon and radiocarbon in the Pacific",
    year = "1969",
    journal = "Journal of Geophysical Research Atmospheres",
    url = "https://doi.org/10.1029/jc074i023p05491",
    doi = "10.1029/jc074i023p05491",
    openalex = "W2143855233"
}

The release of carbon dioxide into the atmosphere by the burning of fossil fuels is significantly altering the carbon cycle by adding to the amount of carbon in the atmosphere and in the more rapidly interacting portions of the biosphere and oceans. In order better to assess these changes, the basis for calculating global CO2 emissions is reviewed and new annual values are computed for the period 1800 through 1969. The world average fractions of carbon in coal and lignite, estimated from calorific data, are found to be lower than previously assumed. When account is taken of handling losses and partial diversion to produce petrochemicals, road asphalt, and other non-fuels, the calculated CO2 emissions are further reduced by several percent even after allowing that most unburned materials eventually oxidize to CO2 in the environment. On the other hand, the production of CO2 by kilning of limestone adds 1 to 2% to the annual totals. The cumulative increase in carbon in the short term carbon cycle, owing to man's industrial and domestic activities up to 1970, is estimated to be 1.12 + 0.14 × 1017 g (4.1 ± 0.5 × 1017 g CO2), or about 18% of the amount of CO2 in the atmosphere during the late nineteenth century.DOI: 10.1111/j.2153-3490.1973.tb01604.x

@article{doi103402tellusav25i29652,
    author = "Keeling, Charles D.",
    title = "Industrial production of carbon dioxide from fossil fuels and limestone",
    year = "1973",
    journal = "Tellus A Dynamic Meteorology and Oceanography",
    abstract = "The release of carbon dioxide into the atmosphere by the burning of fossil fuels is significantly altering the carbon cycle by adding to the amount of carbon in the atmosphere and in the more rapidly interacting portions of the biosphere and oceans. In order better to assess these changes, the basis for calculating global CO2 emissions is reviewed and new annual values are computed for the period 1800 through 1969. The world average fractions of carbon in coal and lignite, estimated from calorific data, are found to be lower than previously assumed. When account is taken of handling losses and partial diversion to produce petrochemicals, road asphalt, and other non-fuels, the calculated CO2 emissions are further reduced by several percent even after allowing that most unburned materials eventually oxidize to CO2 in the environment. On the other hand, the production of CO2 by kilning of limestone adds 1 to 2\% to the annual totals. The cumulative increase in carbon in the short term carbon cycle, owing to man's industrial and domestic activities up to 1970, is estimated to be 1.12 + 0.14 × 1017 g (4.1 ± 0.5 × 1017 g CO2), or about 18\% of the amount of CO2 in the atmosphere during the late nineteenth century.DOI: 10.1111/j.2153-3490.1973.tb01604.x",
    url = "https://doi.org/10.3402/tellusa.v25i2.9652",
    doi = "10.3402/tellusa.v25i2.9652",
    openalex = "W4246011515"
}

@misc{ralph1974twentyfive5,
    author = "Ralph, E. K. and Michael, H. N",
    title = "Twenty-five years of radiocarbon dating",
    year = "1974",
    howpublished = "American Scientist, v. 62, p. 553-560",
    note = "talkorigins\_source = {true}; raw\_reference = {Ralph, E. K., and Michael, H. N., 1974, Twenty-five years of radiocarbon dating: American Scientist, v. 62, p. 553-560.}"
}

Phenomena related to the natural carbon cycle as the 14C distribution between atmosphere and ocean and the atmospheric response to the input of fossil fuel CO 2 and of 14 C produced in nuclear weapon tests have been quantitatively discussed by other authors using box models. However the exchange coefficients derived from the natural 14 C distribution do not agree with those valid to describe the short-term phenomena. A model consisting of a well mixed atmospheric box coupled to a long-term biosphere, of an ocean surface box and a diffusive deep ocean is discussed. The dynamic parameters were derived from the preindustrial 14 C distribution in atmosphere and ocean. A consistent description of phenomena with completely different characteristic times is possible, because in the box diffusion model the flux from mixed layer to deep sea increases for decreasing time constants of the perturbations. This is in contrary to box models where it is essentially independent of the time constants if they are smaller than a few hundred years. Due to this fact our model is valid for predictions of the atmospheric CO 2 response to the various possible future CO 2 input time functions.

@article{doi103402tellusav27i29900,
    author = "Oeschger, H. and Siegenthaler, U. and Schotterer, U. and Gugelmann, A.",
    title = "A box diffusion model to study the carbon dioxide exchange in nature",
    year = "1975",
    journal = "Tellus A Dynamic Meteorology and Oceanography",
    abstract = "Phenomena related to the natural carbon cycle as the 14C distribution between atmosphere and ocean and the atmospheric response to the input of fossil fuel CO 2 and of 14 C produced in nuclear weapon tests have been quantitatively discussed by other authors using box models. However the exchange coefficients derived from the natural 14 C distribution do not agree with those valid to describe the short-term phenomena. A model consisting of a well mixed atmospheric box coupled to a long-term biosphere, of an ocean surface box and a diffusive deep ocean is discussed. The dynamic parameters were derived from the preindustrial 14 C distribution in atmosphere and ocean. A consistent description of phenomena with completely different characteristic times is possible, because in the box diffusion model the flux from mixed layer to deep sea increases for decreasing time constants of the perturbations. This is in contrary to box models where it is essentially independent of the time constants if they are smaller than a few hundred years. Due to this fact our model is valid for predictions of the atmospheric CO 2 response to the various possible future CO 2 input time functions.",
    url = "https://doi.org/10.3402/tellusa.v27i2.9900",
    doi = "10.3402/tellusa.v27i2.9900",
    openalex = "W2087582584",
    references = "doi101002qj49706427503, doi10100797814684198636, doi101029jc074i023p05491, doi101029jz065i009p02903, doi101029jz068i013p03899, doi101111j215334901957tb01848x, doi101126science1223166415a, doi103402tellusav12i29366, doi103402tellusav25i29652, doi103402tellusav9i19075"
}

Archaeologists, along with other Quaternary researchers, seldom rely upon a single radiocarbon determination to provide an estimate of the age of the phenomenon which is the object of their study. There is an evident need for an explicitly formulated procedure for comparing sets of radiocarbon determinations from the same and from adjacent strata or sites, and for combining these where statistical and archaeological criteria indicate that this combination is warranted. The present contribution provides explicit modelling for a series of recommended procedures, a critique of previous methods, and paradigms for application of the recommended procedures.

@article{doi101111j147547541978tb00208x,
    author = "Ward, Graeme and Wilson, Susan R.",
    title = "PROCEDURES FOR COMPARING AND COMBINING RADIOCARBON AGE DETERMINATIONS: A CRITIQUE",
    year = "1978",
    journal = "Archaeometry",
    abstract = "Archaeologists, along with other Quaternary researchers, seldom rely upon a single radiocarbon determination to provide an estimate of the age of the phenomenon which is the object of their study. There is an evident need for an explicitly formulated procedure for comparing sets of radiocarbon determinations from the same and from adjacent strata or sites, and for combining these where statistical and archaeological criteria indicate that this combination is warranted. The present contribution provides explicit modelling for a series of recommended procedures, a critique of previous methods, and paradigms for application of the recommended procedures.",
    url = "https://doi.org/10.1111/j.1475-4754.1978.tb00208.x",
    doi = "10.1111/j.1475-4754.1978.tb00208.x",
    openalex = "W2004966701",
    references = "doi101017s0003598x00070277, doi101111j147547541974tb01088x, doi101126science1193083135, doi102307276313, doi102307279583, openalexw84870047"
}

@misc{grootes1978carbon142,
    author = "Grootes, P. M",
    title = "Carbon-14 time scale extended",
    year = "1978",
    howpublished = "comparison of chronologies: Science, v. 200, p. 11-21",
    note = "talkorigins\_source = {true}; raw\_reference = {Grootes, P. M., 1978, Carbon-14 time scale extended: comparison of chronologies: Science, v. 200, p. 11-21.}"
}

@misc{stuvier1980changes6,
    author = "Stuvier, M. and Quay, P. D",
    title = "Changes in atmospheric carbon-14 attributed to a variable sun",
    year = "1980",
    howpublished = "Science, v. 207, p. 11-19",
    note = "talkorigins\_source = {true}; raw\_reference = {Stuvier, M., and Quay, P. D., 1980, Changes in atmospheric carbon-14 attributed to a variable sun: Science, v. 207, p. 11-19.}"
}

The global temperature rose by 0.2 degrees C between the middle 1960's and 1980, yielding a warming of 0.4 degrees C in the past century. This temperature increase is consistent with the calculated greenhouse effect due to measured increases of atmospheric carbon dioxide. Variations of volcanic aerosols and possibly solar luminosity appear to be primary causes of observed fluctuations about the mean trend of increasing temperature. It is shown that the anthropogenic carbon dioxide warming should emerge from the noise level of natural climate variability by the end of the century, and there is a high probability of warming in the 1980's. Potential effects on climate in the 21st century include the creation of drought-prone regions in North America and central Asia as part of a shifting of climatic zones, erosion of the West Antarctic ice sheet with a consequent worldwide rise in sea level, and opening of the fabled Northwest Passage.

@article{doi101126science2134511957,
    author = "Hansen, James E. and Johnson, David W. and Lacis, Andrew A. and Lebedeff, S. and Lee, P. and Rind, David and Russell, Gary L.",
    title = "Climate Impact of Increasing Atmospheric Carbon Dioxide",
    year = "1981",
    journal = "Science",
    abstract = "The global temperature rose by 0.2 degrees C between the middle 1960's and 1980, yielding a warming of 0.4 degrees C in the past century. This temperature increase is consistent with the calculated greenhouse effect due to measured increases of atmospheric carbon dioxide. Variations of volcanic aerosols and possibly solar luminosity appear to be primary causes of observed fluctuations about the mean trend of increasing temperature. It is shown that the anthropogenic carbon dioxide warming should emerge from the noise level of natural climate variability by the end of the century, and there is a high probability of warming in the 1980's. Potential effects on climate in the 21st century include the creation of drought-prone regions in North America and central Asia as part of a shifting of climatic zones, erosion of the West Antarctic ice sheet with a consequent worldwide rise in sea level, and opening of the fabled Northwest Passage.",
    url = "https://doi.org/10.1126/science.213.4511.957",
    doi = "10.1126/science.213.4511.957",
    openalex = "W1995986570",
    references = "broecker1979fate, doi101029jc085ic10p05529, doi101029rg013i001p00001, doi101038271321a0, doi101098rsta19700010, doi101126science19142321131, doi101126science2064417409, doi1011751520046919640210361teotaw20co2, doi1011751520046919670240241teotaw20co2, doi103402tellusav27i29900, openalexw2916805370"
}

We estimate that recent increases in organic carbon accumulation in the sediments of lakes and reservoirs amount to about 0.02 m? 10 15 gC yr -1 and 0.2 m? 10 15 gC yr -1, respectively. The reservoir accumulation represents a small but significant fraction of the carbon missing in current global budgets. DOI: 10.1111/j.2153-3490.1982.tb01837.x

@article{doi101111j215334901982tb01837x,
    author = "Mulholland, Patrick J. and Elwood, Jerry W.",
    title = "The role of lake and reservoir sediments as sinks in the perturbed global carbon cycle",
    year = "1982",
    journal = "Tellus",
    abstract = "We estimate that recent increases in organic carbon accumulation in the sediments of lakes and reservoirs amount to about 0.02 m? 10 15 gC yr -1 and 0.2 m? 10 15 gC yr -1, respectively. The reservoir accumulation represents a small but significant fraction of the carbon missing in current global budgets. DOI: 10.1111/j.2153-3490.1982.tb01837.x",
    url = "https://doi.org/10.1111/j.2153-3490.1982.tb01837.x",
    doi = "10.1111/j.2153-3490.1982.tb01837.x",
    openalex = "W2147506546"
}

We estimate that recent increases in organic carbon accumulation in the sediments of lakes and reservoirs amount to about 0.02. 1015 gC yr-1 and 0.2. 1015 gC yr-1, respectively. The reservoir accumulation represents a small but significant fraction of the carbon missing in current global budgets.

@article{doi103402tellusav34i510834,
    author = "Mulholland, Patrick J. and Elwood, Jerry W.",
    title = "The role of lake and reservoir sediments as sinks in the perturbed global carbon cycle",
    year = "1982",
    journal = "Tellus A Dynamic Meteorology and Oceanography",
    abstract = "We estimate that recent increases in organic carbon accumulation in the sediments of lakes and reservoirs amount to about 0.02. 1015 gC yr-1 and 0.2. 1015 gC yr-1, respectively. The reservoir accumulation represents a small but significant fraction of the carbon missing in current global budgets.",
    url = "https://doi.org/10.3402/tellusa.v34i5.10834",
    doi = "10.3402/tellusa.v34i5.10834",
    openalex = "W4250333128"
}

@misc{suess1982personal7,
    author = "Suess, H. E",
    title = "Personal communication cited as s ource of Figure 1, P. 14, in E. M. Druffel [1982] Banded corals",
    year = "1982",
    howpublished = "changes in oceanic carbon-14 during the Little Ice Age: Science, v. 218, p. 13-19",
    note = "talkorigins\_source = {true}; raw\_reference = {Suess, H. E., 1982, Personal communication cited as s ource of Figure 1, P. 14, in E. M. Druffel [1982] Banded corals: changes in oceanic carbon-14 during the Little Ice Age: Science, v. 218, p. 13-19.}"
}

@misc{weber1982answers8,
    author = "Weber, C. G",
    title = "Answers to creationist attacks on Carbon-14 dating",
    year = "1982",
    howpublished = "Creation/Evolution, v. 3, p. 23-29",
    note = "talkorigins\_source = {true}; raw\_reference = {Weber, C. G., 1982, Answers to creationist attacks on Carbon-14 dating: Creation/Evolution, v. 3, p. 23-29.}"
}

Inputs of terrestrial peat carbon to the nearshore Alaskan Beaufort Sea from erosion and fluvial transport are of the same magnitude as in situ primary production within 10 kilometers of shore. Nevertheless, carbon-13/carbon-12 ratios and carbon-14 abundances in marine organisms show that only small amounts of the terrestrial carbon are transferred beyond the microbial level. Freshwater organisms, however, are heavily dependent on peat, as shown by pronounced seasonal radiocarbon depressions in resident fish and ducks. Tundra ponds and lakes are areas where accumulated terrestrial peat carbon is apparently transferred to aquatic insect larvae and passed on to higher organisms. The lack of functionally analogous abundant marine prey organisms may explain why peat carbon is not efficiently transferred to apical food web species in the marine environment.

@article{doi101126science21945881068,
    author = "Schell, Donald M.",
    title = "Carbon-13 and Carbon-14 Abundances in Alaskan Aquatic Organisms: Delayed Production from Peat in Arctic Food Webs",
    year = "1983",
    journal = "Science",
    abstract = "Inputs of terrestrial peat carbon to the nearshore Alaskan Beaufort Sea from erosion and fluvial transport are of the same magnitude as in situ primary production within 10 kilometers of shore. Nevertheless, carbon-13/carbon-12 ratios and carbon-14 abundances in marine organisms show that only small amounts of the terrestrial carbon are transferred beyond the microbial level. Freshwater organisms, however, are heavily dependent on peat, as shown by pronounced seasonal radiocarbon depressions in resident fish and ducks. Tundra ponds and lakes are areas where accumulated terrestrial peat carbon is apparently transferred to aquatic insect larvae and passed on to higher organisms. The lack of functionally analogous abundant marine prey organisms may explain why peat carbon is not efficiently transferred to apical food web species in the marine environment.",
    url = "https://doi.org/10.1126/science.219.4588.1068",
    doi = "10.1126/science.219.4588.1068",
    openalex = "W1971496824"
}

@article{doi1010160020708x84900395,
    author = "Lowe, David C.",
    title = "Preparation of graphite targets for radiocarbon dating by tandem accelarator mass spectrometer (TAMS)",
    year = "1984",
    journal = "The International Journal of Applied Radiation and Isotopes",
    url = "https://doi.org/10.1016/0020-708x(84)90039-5",
    doi = "10.1016/0020-708x(84)90039-5",
    openalex = "W2059579819"
}

@article{doi1010160305440384900505,
    author = "Wand, J.O. and Gillespie, Richard and Hedges, R.E.M.",
    title = "Sample preparation for accelerator-based radiocarbon dating",
    year = "1984",
    journal = "Journal of Archaeological Science",
    url = "https://doi.org/10.1016/0305-4403(84)90050-5",
    doi = "10.1016/0305-4403(84)90050-5",
    openalex = "W1966789811"
}

Water column inventories are calculated for bomb radiocarbon at all the stations occupied during the GEOSECS and NORPAX expeditions and for the available TTO stations. The pattern of global inventories obtained in this way suggests that a sizable portion of the bomb radiocarbon that entered the Antarctic, the northern Pacific, and the tropical ocean has been transported to the adjacent temperate zones. A strategy for utilizing these inventory anomalies as constraints on global ocean circulation models is presented. Essential to this strategy are the improvement of our knowledge of the pattern of wind speed over the ocean, the establishment of the wind speed dependence of the rate of gas exchange between the atmosphere and sea, and the continued mapping of the distribution of bomb‐produced radiocarbon in the sea.

@article{doi101029jc090ic04p06953,
    author = "Broecker, Wallace S. and Peng, Tsung‐Hung and Östlund, Göte and Stuiver, Minze",
    title = "The distribution of bomb radiocarbon in the ocean",
    year = "1985",
    journal = "Journal of Geophysical Research Atmospheres",
    abstract = "Water column inventories are calculated for bomb radiocarbon at all the stations occupied during the GEOSECS and NORPAX expeditions and for the available TTO stations. The pattern of global inventories obtained in this way suggests that a sizable portion of the bomb radiocarbon that entered the Antarctic, the northern Pacific, and the tropical ocean has been transported to the adjacent temperate zones. A strategy for utilizing these inventory anomalies as constraints on global ocean circulation models is presented. Essential to this strategy are the improvement of our knowledge of the pattern of wind speed over the ocean, the establishment of the wind speed dependence of the rate of gas exchange between the atmosphere and sea, and the continued mapping of the distribution of bomb‐produced radiocarbon in the sea.",
    url = "https://doi.org/10.1029/jc090ic04p06953",
    doi = "10.1029/jc090ic04p06953",
    openalex = "W2020071468",
    references = "doi101029jz065i009p02903, doi101111j215334901975tb01671x"
}

Seasonal variations in 18 O content, in acidity, and in dust content have been used to count annual layers in the Dye 3 deep ice core back to the Late Glacial. In this way the Pleistocene/Holocene boundary has been absolutely dated to 8770 BC with an estimated error limit of ± 150 years. If compared to the conventional 14 C age of the same boundary a value of Δ 14 C = 53 ± 13‰ is obtained. This Δ 14 C value suggests that 14 C levels during the Late Glacial were not substantially higher than during the Postglacial.

@article{doi101017s0033822200007384,
    author = "Hammer, C. U. and Clausen, Henrik and Tauber, Henrik",
    title = "Ice-Core Dating of the Pleistocene/Holocene Boundary Applied to a Calibration of the 14 C Time Scale",
    year = "1986",
    journal = "Radiocarbon",
    abstract = "Seasonal variations in 18 O content, in acidity, and in dust content have been used to count annual layers in the Dye 3 deep ice core back to the Late Glacial. In this way the Pleistocene/Holocene boundary has been absolutely dated to 8770 BC with an estimated error limit of ± 150 years. If compared to the conventional 14 C age of the same boundary a value of Δ 14 C = 53 ± 13‰ is obtained. This Δ 14 C value suggests that 14 C levels during the Late Glacial were not substantially higher than during the Postglacial.",
    url = "https://doi.org/10.1017/s0033822200007384",
    doi = "10.1017/s0033822200007384",
    openalex = "W2486694309"
}

Calibration curves spanning several millennia are now available in this special issue of R adiocarbon. These curves, nearly all derived from the 14 C age determinations of wood samples, are to be used for the age conversion of samples that were formed through use of atmospheric CO 2. When samples are formed in reservoirs (eg, lakes and oceans) that differ in specific 14 C content from the atmosphere, an age adjustment is needed because a conventional 14 C age, although taking into account 14 C (and 13 C) fractionation, does not correct for the difference in specific 14 C activity (Stuiver & Polach, 1977). The 14 C ages of samples grown in these environments are too old, and a reservoir age correction has to be applied. This phenomenon has been referred to as the reservoir effect (Stuiver & Polach, 1977).

@article{doi101017s0033822200060264,
    author = "Stuiver, Minze and Pearson, G. W. and Braziunas, T. F.",
    title = "Radiocarbon Age Calibration of Marine Samples Back to 9000 Cal Yr BP",
    year = "1986",
    journal = "Radiocarbon",
    abstract = "Calibration curves spanning several millennia are now available in this special issue of R adiocarbon. These curves, nearly all derived from the 14 C age determinations of wood samples, are to be used for the age conversion of samples that were formed through use of atmospheric CO 2. When samples are formed in reservoirs (eg, lakes and oceans) that differ in specific 14 C content from the atmosphere, an age adjustment is needed because a conventional 14 C age, although taking into account 14 C (and 13 C) fractionation, does not correct for the difference in specific 14 C activity (Stuiver \& Polach, 1977). The 14 C ages of samples grown in these environments are too old, and a reservoir age correction has to be applied. This phenomenon has been referred to as the reservoir effect (Stuiver \& Polach, 1977).",
    url = "https://doi.org/10.1017/s0033822200060264",
    doi = "10.1017/s0033822200060264",
    openalex = "W1600028230"
}

We investigate the carbon cycle in Lake Washington for the year 1980 using monthly measurements of the dissolved inorganic carbon (DIC) and its 13 C: 12 C isotopic composition. Mass balances of DIC and 13 C: 12 C yield estimates of CO 2 gas exchange rates and net organic carbon production rates. Between 24 June and 13 August, the calculated CO 2 gas invasion rate of 0.80 × 10 6 mol C d −1 is nearly equal to the river DIC inflow rate. The calculated epilimnetic net organic carbon production rate is 0.68 × 10 6 mol C d −1, about 20–30% of primary productivity estimated from 14 C‐fixation experiments and ETS‐derived respiration rates. Metalimnetic and hypolimnetic DIC increase rates and porewater DIC gradients in hypolimnetic sediments indicate that remineralization of particulate organic carbon (POC) previously deposited in the sediments is a major (0.5 × 10 6 mol C d −1) DIC source to the lake during summer. For the whole year, summertime CO 2 gas invasion balances wintertime CO 2 gas evasion and DIC and POC outflow balance DIC and POC inflow rates, implying no net carbon burial in the sediments during 1980. This contrasts with the measured long term sedimentation‐rate‐derived carbon burial rate of 0.8 × 10 6 mol C d −1. Year‐to‐year variability in summertime primary production rates largely determines net gains or losses of carbon via CO 2 gas exchange and sedimentation.

@article{doi104319lo19863130596,
    author = "Quay, Paul D. and Emerson, Steve and Quay, B. M. and Devol, Allan H.",
    title = "The carbon cycle for Lake Washington—A stable isotope study1",
    year = "1986",
    journal = "Limnology and Oceanography",
    abstract = "We investigate the carbon cycle in Lake Washington for the year 1980 using monthly measurements of the dissolved inorganic carbon (DIC) and its 13 C: 12 C isotopic composition. Mass balances of DIC and 13 C: 12 C yield estimates of CO 2 gas exchange rates and net organic carbon production rates. Between 24 June and 13 August, the calculated CO 2 gas invasion rate of 0.80 × 10 6 mol C d −1 is nearly equal to the river DIC inflow rate. The calculated epilimnetic net organic carbon production rate is 0.68 × 10 6 mol C d −1, about 20–30\% of primary productivity estimated from 14 C‐fixation experiments and ETS‐derived respiration rates. Metalimnetic and hypolimnetic DIC increase rates and porewater DIC gradients in hypolimnetic sediments indicate that remineralization of particulate organic carbon (POC) previously deposited in the sediments is a major (0.5 × 10 6 mol C d −1) DIC source to the lake during summer. For the whole year, summertime CO 2 gas invasion balances wintertime CO 2 gas evasion and DIC and POC outflow balance DIC and POC inflow rates, implying no net carbon burial in the sediments during 1980. This contrasts with the measured long term sedimentation‐rate‐derived carbon burial rate of 0.8 × 10 6 mol C d −1. Year‐to‐year variability in summertime primary production rates largely determines net gains or losses of carbon via CO 2 gas exchange and sedimentation.",
    url = "https://doi.org/10.4319/lo.1986.31.3.0596",
    doi = "10.4319/lo.1986.31.3.0596",
    openalex = "W2163502098"
}

@misc{dorn1986cationratio1,
    author = "Dorn, R. I. et al",
    title = "Cation-ratio and accelerator radiocarbon dating of rock varnish on Mojave artifacts and landforms",
    year = "1986",
    howpublished = "Science, v. 231, p. 830- 833",
    note = "talkorigins\_source = {true}; raw\_reference = {Dorn, R. I. et al., 1986, Cation-ratio and accelerator radiocarbon dating of rock varnish on Mojave artifacts and landforms: Science, v. 231, p. 830- 833.}"
}

Journal Article Carbon Isotopes in Photosynthesis: Fractionation techniques may reveal new aspects of carbon dynamics in plants Get access Marion H. O'Leary Marion H. O'Leary Search for other works by this author on: Oxford Academic Google Scholar BioScience, Volume 38, Issue 5, May 1988, Pages 328–336, https://doi.org/10.2307/1310735 Published: 01 May 1988

@article{doi1023071310735,
    author = "O’Leary, Marion H.",
    title = "Carbon Isotopes in Photosynthesis",
    year = "1988",
    journal = "BioScience",
    abstract = "Journal Article Carbon Isotopes in Photosynthesis: Fractionation techniques may reveal new aspects of carbon dynamics in plants Get access Marion H. O'Leary Marion H. O'Leary Search for other works by this author on: Oxford Academic Google Scholar BioScience, Volume 38, Issue 5, May 1988, Pages 328–336, https://doi.org/10.2307/1310735 Published: 01 May 1988",
    url = "https://doi.org/10.2307/1310735",
    doi = "10.2307/1310735",
    openalex = "W2063987912",
    references = "doi1010160012821x74900788, doi1010160012825273900287, doi1010160016703753900015, doi1010160016703757900248, doi1010160031942281851345, doi101016b9780444422255500012"
}

@article{doi101038337611a0,
    author = "Damon, Paul E. and Donahue, D. J. and Gore, B. H. and Hatheway, A. L. and Jull, A. J. T. and Linick, T W and Sercel, P. J. and Toolin, Laurence J. and Bronk, Christopher and Hall, E. T. and Hedges, R.E.M. and Housley, Rupert A. and Law, I. A. and Perry, C. and Bonani, Georges and Trumbore, Susan and Woelfli, W. and Ambers, Janet and Bowman, Sheridan and Leese, Morven and TITE, M. S.",
    title = "Radiocarbon dating of the Shroud of Turin",
    year = "1989",
    journal = "Nature",
    url = "https://doi.org/10.1038/337611a0",
    doi = "10.1038/337611a0",
    openalex = "W1998268672",
    references = "doi101017s0033822200056988"
}

A detailed late‐glacial radiocarbon stratigraphy for the Swiss Plateau has been established on the basis of over 90 accelerator 14 C dates on terrestrial plant macrofossils. Two plateaux of constant., 14 C age were observed, occurring at 12,700 B.P. and at 10,000 B.P. The consequences of these plateaux for palaeo‐ecological investigations are threefold: (1) a more refined 14 C dating within the plateaux is not possible, (2) in teleconnections between different sites (if based on 14 C dating and concerning the periods around 12,700 B.P. and 10,000 B.P.) events are considered synchronous which are only synchronous within a plateau of constant age, and (3) exact time‐depth relationship and therefore influx calculations are made impossible during these plateau periods. A comparison of the radiocarbon ages derived from terrestrial, telmatic and limnic material at different sites on the Swiss Plateau yields a proposal for modifying the zonation system of Welten for the Late‐Glacial. By retaining the limits of chronozones (at 13, 12, 11 and 10ka B.P.) and by refining the palynostratigraphic criteria for the limits of biozones, a separation between chrono‐ and biozonation at the beginning of the Belling and at the beginning of the Younger Dryas becomes obvious.

@article{doi101111j150238851989tb00381x,
    author = "Ammann, Brigitta and Lotter, André F.",
    title = "Late‐Glacial radiocarbon‐ and palynostratigraphy on the Swiss Plateau",
    year = "1989",
    journal = "Boreas",
    abstract = "A detailed late‐glacial radiocarbon stratigraphy for the Swiss Plateau has been established on the basis of over 90 accelerator 14 C dates on terrestrial plant macrofossils. Two plateaux of constant., 14 C age were observed, occurring at 12,700 B.P. and at 10,000 B.P. The consequences of these plateaux for palaeo‐ecological investigations are threefold: (1) a more refined 14 C dating within the plateaux is not possible, (2) in teleconnections between different sites (if based on 14 C dating and concerning the periods around 12,700 B.P. and 10,000 B.P.) events are considered synchronous which are only synchronous within a plateau of constant age, and (3) exact time‐depth relationship and therefore influx calculations are made impossible during these plateau periods. A comparison of the radiocarbon ages derived from terrestrial, telmatic and limnic material at different sites on the Swiss Plateau yields a proposal for modifying the zonation system of Welten for the Late‐Glacial. By retaining the limits of chronozones (at 13, 12, 11 and 10ka B.P.) and by refining the palynostratigraphic criteria for the limits of biozones, a separation between chrono‐ and biozonation at the beginning of the Belling and at the beginning of the Younger Dryas becomes obvious.",
    url = "https://doi.org/10.1111/j.1502-3885.1989.tb00381.x",
    doi = "10.1111/j.1502-3885.1989.tb00381.x",
    openalex = "W1997885955"
}

We present here the method we use to convert to radiocarbon ages (14 C/ 13 C) ratios measured in the Arizona Accelerator Mass Spectrometer facility. We describe the procedures we use to convert sample and standard isotope ratios to values appropriate for calculation of radiocarbon ages. We also discuss, in some detail, corrections to account for sample contamination.

@article{doi101017s0033822200040121,
    author = "Donahue, D. J. and Linick, T W and Jull, A. J. T.",
    title = "Isotope-Ratio and Background Corrections for Accelerator Mass Spectrometry Radiocarbon Measurements",
    year = "1990",
    journal = "Radiocarbon",
    abstract = "We present here the method we use to convert to radiocarbon ages (14 C/ 13 C) ratios measured in the Arizona Accelerator Mass Spectrometer facility. We describe the procedures we use to convert sample and standard isotope ratios to values appropriate for calculation of radiocarbon ages. We also discuss, in some detail, corrections to account for sample contamination.",
    url = "https://doi.org/10.1017/s0033822200040121",
    doi = "10.1017/s0033822200040121",
    openalex = "W2314696016",
    references = "doi101017s0033822200003672, doi101017s0033822200006159, doi101017s0033822200007670, openalexw1928750549"
}

@article{doi1010160305440391900784,
    author = "Stafford, Thomas W. and Hare, P. E. and Currie, Lloyd A. and Jull, A. J. T. and Donahue, Douglas J.",
    title = "Accelerator radiocarbon dating at the molecular level",
    year = "1991",
    journal = "Journal of Archaeological Science",
    url = "https://doi.org/10.1016/0305-4403(91)90078-4",
    doi = "10.1016/0305-4403(91)90078-4",
    openalex = "W2067762840",
    references = "doi101017s0033822200040121, doi101017s0033822200056988"
}

Arctic tundra has large amounts of stored carbon and is thought to be a sink for atmospheric carbon dioxide (CO(2)) (0.1 to 0.3 petagram of carbon per year) (1 petagram = 10(15) grams). But this estimate of carbon balance is only for terrestrial ecosystems. Measurements of the partial pressure of CO(2) in 29 aquatic ecosystems across arctic Alaska showed that in most cases (27 of 29) CO(2) was released to the atmosphere. This CO(2) probably originates in terrestrial environments; erosion of particulate carbon plus ground-water transport of dissolved carbon from tundra contribute to the CO(2) flux from surface waters to the atmosphere. If this mechanism is typical of that of other tundra areas, then current estimates of the arctic terrestrial sink for atmospheric CO(2) may be 20 percent too high.

@article{doi101126science2514991298,
    author = "Kling, George W. and Kipphut, George W. and Miller, Michael C.",
    title = "Arctic Lakes and Streams as Gas Conduits to the Atmosphere: Implications for Tundra Carbon Budgets",
    year = "1991",
    journal = "Science",
    abstract = "Arctic tundra has large amounts of stored carbon and is thought to be a sink for atmospheric carbon dioxide (CO(2)) (0.1 to 0.3 petagram of carbon per year) (1 petagram = 10(15) grams). But this estimate of carbon balance is only for terrestrial ecosystems. Measurements of the partial pressure of CO(2) in 29 aquatic ecosystems across arctic Alaska showed that in most cases (27 of 29) CO(2) was released to the atmosphere. This CO(2) probably originates in terrestrial environments; erosion of particulate carbon plus ground-water transport of dissolved carbon from tundra contribute to the CO(2) flux from surface waters to the atmosphere. If this mechanism is typical of that of other tundra areas, then current estimates of the arctic terrestrial sink for atmospheric CO(2) may be 20 percent too high.",
    url = "https://doi.org/10.1126/science.251.4991.298",
    doi = "10.1126/science.251.4991.298",
    openalex = "W2030348009",
    references = "doi101007bf00377129, doi1010160277379187900321, doi1010160304420374900152, doi101126science21945881068, doi101126science22746911224, doi101126science22947201383, doi101126science2344777689, doi101126science24749491431, doi1023071550883, doi1023071938918"
}

Boreal and subarctic peatlands comprise a carbon pool of 455 Pg that has accumulated during the postglacial period at an average net rate of 0.096 Pg/yr (1 Pg = 10 1 5 g). Using Clymo's (1984) model, the current rate is estimated at 0.076 Pg/yr. Longterm drainage of these peatlands is estimated to be causing the oxidation to CO 2 of a little more than 0.0085 Pg/yr, with conbustion of fuel peat adding °0.026 Pg/yr. Emissions of CH 4 are estimated to release ° 0.046 Pg of carbon annually. Uncertainties beset estimates of both stocks and fluxes, particularly with regard to Soviet peatlands. The influence of water table alterations upon fluxes of both CO 2 and CH 4 is in great need of investigation over a wide range of peatland environments, especially in regions where permafrost melting, thermokarst erosion, and the development of thaw lakes are likely results of climatic warming. The role of fire in the carbon cycle of peatlands also deserves increased attention. Finally, satellite-monitoring of the abundance of open water in the peatlands of the West Siberian Plain and the Hudson/James Bay Lowland is suggested as a likely method of detecting early effects of climatic warming upon boreal and subarctic peatlands.

@article{doi1023071941811,
    author = "Gorham, Eville",
    title = "Northern Peatlands: Role in the Carbon Cycle and Probable Responses to Climatic Warming",
    year = "1991",
    journal = "Ecological Applications",
    abstract = "Boreal and subarctic peatlands comprise a carbon pool of 455 Pg that has accumulated during the postglacial period at an average net rate of 0.096 Pg/yr (1 Pg = 10 1 5 g). Using Clymo's (1984) model, the current rate is estimated at 0.076 Pg/yr. Longterm drainage of these peatlands is estimated to be causing the oxidation to CO 2 of a little more than 0.0085 Pg/yr, with conbustion of fuel peat adding °0.026 Pg/yr. Emissions of CH 4 are estimated to release ° 0.046 Pg of carbon annually. Uncertainties beset estimates of both stocks and fluxes, particularly with regard to Soviet peatlands. The influence of water table alterations upon fluxes of both CO 2 and CH 4 is in great need of investigation over a wide range of peatland environments, especially in regions where permafrost melting, thermokarst erosion, and the development of thaw lakes are likely results of climatic warming. The role of fire in the carbon cycle of peatlands also deserves increased attention. Finally, satellite-monitoring of the abundance of open water in the peatlands of the West Siberian Plain and the Hudson/James Bay Lowland is suggested as a likely method of detecting early effects of climatic warming upon boreal and subarctic peatlands.",
    url = "https://doi.org/10.2307/1941811",
    doi = "10.2307/1941811",
    openalex = "W2023906603",
    references = "doi101029gb001i001p00061, doi101029gb002i004p00371, doi101038298156a0, doi101038346160a0, doi101038scientificamerican048936, doi101098rstb19840002, doi101126science2344777689, doi1023072260396, doi104141cjss89004, openalexw3162656244"
}

The radiocarbon ages of dendrochronologically dated wood spanning the AD 1950–6000 BC interval are now available for Seattle (10-yr samples, Stuiver & Becker 1993) and Belfast (20-yr samples, Pearson, Becker & Qua 1993; Pearson & Qua 1993). The results of both laboratories were previously combined to generate a bidecadal calibration curve spanning nearly 4500 years (Stuiver & Pearson 1986; Pearson & Stuiver 1986). We now find that minor corrections must be applied to the published data sets, and therefore, give new bidecadal radiocarbon age information for 2500–6000 BC, as well as corrected radiocarbon age averages for AD 1950–500 BC. Corrected average 14 C ages for the 500–2500 BC interval are given separately (Pearson & Stuiver 1993). The Seattle corrections (in the 10–30 14 C-yr range) are discussed in Stuiver and Becker (1993), whereas Pearson and Qua (1993) provide information on Belfast corrections (averaging 16 yr). All dates reported here are conventional radiocarbon dates, as defined in Stuiver and Polach (1977). Belfast 14 C ages back to 5210 BC were obtained on wood from the Irish oak chronology (Pearson et al. 1986). Wood from the German oak chronology (Becker 1993) was used by Belfast for the 5000–6000 BC interval. For the overlapping interval (5000–5210 BC), Belfast reports weighted Irish wood/German wood 14 C age averages. The Seattle 14 C ages for the AD interval were either on Douglas fir wood from the US Pacific Northwest, or Sequoia wood from California (Stuiver 1982). The BC materials measured in Seattle were mostly part of the German oak chronology. Thirteen samples (5680–5810 BC) from the US bristlecone pine chronology (Ferguson & Graybill 1983) were measured in Seattle as well. Here, the final Seattle decadal 14 C ages resulted from averaging German oak and bristlecone pine ages.

@article{doi101017s0033822200013783,
    author = "Stuiver, Minze and Pearson, Gordon W.",
    title = "High-Precision Bidecadal Calibration of the Radiocarbon Time Scale, AD 1950–500 BC and 2500–6000 BC",
    year = "1993",
    journal = "Radiocarbon",
    abstract = "The radiocarbon ages of dendrochronologically dated wood spanning the AD 1950–6000 BC interval are now available for Seattle (10-yr samples, Stuiver \& Becker 1993) and Belfast (20-yr samples, Pearson, Becker \& Qua 1993; Pearson \& Qua 1993). The results of both laboratories were previously combined to generate a bidecadal calibration curve spanning nearly 4500 years (Stuiver \& Pearson 1986; Pearson \& Stuiver 1986). We now find that minor corrections must be applied to the published data sets, and therefore, give new bidecadal radiocarbon age information for 2500–6000 BC, as well as corrected radiocarbon age averages for AD 1950–500 BC. Corrected average 14 C ages for the 500–2500 BC interval are given separately (Pearson \& Stuiver 1993). The Seattle corrections (in the 10–30 14 C-yr range) are discussed in Stuiver and Becker (1993), whereas Pearson and Qua (1993) provide information on Belfast corrections (averaging 16 yr). All dates reported here are conventional radiocarbon dates, as defined in Stuiver and Polach (1977). Belfast 14 C ages back to 5210 BC were obtained on wood from the Irish oak chronology (Pearson et al. 1986). Wood from the German oak chronology (Becker 1993) was used by Belfast for the 5000–6000 BC interval. For the overlapping interval (5000–5210 BC), Belfast reports weighted Irish wood/German wood 14 C age averages. The Seattle 14 C ages for the AD interval were either on Douglas fir wood from the US Pacific Northwest, or Sequoia wood from California (Stuiver 1982). The BC materials measured in Seattle were mostly part of the German oak chronology. Thirteen samples (5680–5810 BC) from the US bristlecone pine chronology (Ferguson \& Graybill 1983) were measured in Seattle as well. Here, the final Seattle decadal 14 C ages resulted from averaging German oak and bristlecone pine ages.",
    url = "https://doi.org/10.1017/s0033822200013783",
    doi = "10.1017/s0033822200013783",
    openalex = "W2301005675"
}

Forest systems cover more than 4.1 x 10(9) hectares of the Earth's land area. Globally, forest vegetation and soils contain about 1146 petagrams of carbon, with approximately 37 percent of this carbon in low-latitude forests, 14 percent in mid-latitudes, and 49 percent at high latitudes. Over two-thirds of the carbon in forest ecosystems is contained in soils and associated peat deposits. In 1990, deforestation in the low latitudes emitted 1.6 +/- 0.4 petagrams of carbon per year, whereas forest area expansion and growth in mid- and high-latitude forest sequestered 0.7 +/- 0.2 petagrams of carbon per year, for a net flux to the atmosphere of 0.9 +/- 0.4 petagrams of carbon per year. Slowing deforestation, combined with an increase in forestation and other management measures to improve forest ecosystem productivity, could conserve or sequester significant quantities of carbon. Future forest carbon cycling trends attributable to losses and regrowth associated with global climate and land-use change are uncertain. Model projections and some results suggest that forests could be carbon sinks or sources in the future.

@article{doi101126science2635144185,
    author = "Dixon, Robert K. and Solomon, A. M. and Brown, Sandra and Houghton, R. A. and Trexier, M. C. and Wiśniewski, J.",
    title = "Carbon Pools and Flux of Global Forest Ecosystems",
    year = "1994",
    journal = "Science",
    abstract = "Forest systems cover more than 4.1 x 10(9) hectares of the Earth's land area. Globally, forest vegetation and soils contain about 1146 petagrams of carbon, with approximately 37 percent of this carbon in low-latitude forests, 14 percent in mid-latitudes, and 49 percent at high latitudes. Over two-thirds of the carbon in forest ecosystems is contained in soils and associated peat deposits. In 1990, deforestation in the low latitudes emitted 1.6 +/- 0.4 petagrams of carbon per year, whereas forest area expansion and growth in mid- and high-latitude forest sequestered 0.7 +/- 0.2 petagrams of carbon per year, for a net flux to the atmosphere of 0.9 +/- 0.4 petagrams of carbon per year. Slowing deforestation, combined with an increase in forestation and other management measures to improve forest ecosystem productivity, could conserve or sequester significant quantities of carbon. Future forest carbon cycling trends attributable to losses and regrowth associated with global climate and land-use change are uncertain. Model projections and some results suggest that forests could be carbon sinks or sources in the future.",
    url = "https://doi.org/10.1126/science.263.5144.185",
    doi = "10.1126/science.263.5144.185",
    openalex = "W2046788667",
    references = "doi1010079783642809132, doi101029jd093id08p09341, doi101038361520a0, doi101093forestscience354881, doi101126science24749491431, doi105962bhltitle44956"
}

Data on the partial pressure of carbon dioxide (CO(2)) in the surface waters from a large number of lakes (1835) with a worldwide distribution show that only a small proportion of the 4665 samples analyzed (less than 10 percent) were within +/-20 percent of equilibrium with the atmosphere and that most samples (87 percent) were supersaturated. The mean partial pressure of CO(2) averaged 1036 microatmospheres, about three times the value in the overlying atmosphere, indicating that lakes are sources rather than sinks of atmospheric CO(2). On a global scale, the potential efflux of CO(2) from lakes (about 0.14 x 10(15) grams of carbon per year) is about half as large as riverine transport of organic plus inorganic carbon to the ocean. Lakes are a small but potentially important conduit for carbon from terrestrial sources to the atmospheric sink.

@article{doi101126science26551781568,
    author = "Cole, Jonathan J. and Caraco, Nina F. and Kling, George W. and Kratz, Timothy K.",
    title = "Carbon Dioxide Supersaturation in the Surface Waters of Lakes",
    year = "1994",
    journal = "Science",
    abstract = "Data on the partial pressure of carbon dioxide (CO(2)) in the surface waters from a large number of lakes (1835) with a worldwide distribution show that only a small proportion of the 4665 samples analyzed (less than 10 percent) were within +/-20 percent of equilibrium with the atmosphere and that most samples (87 percent) were supersaturated. The mean partial pressure of CO(2) averaged 1036 microatmospheres, about three times the value in the overlying atmosphere, indicating that lakes are sources rather than sinks of atmospheric CO(2). On a global scale, the potential efflux of CO(2) from lakes (about 0.14 x 10(15) grams of carbon per year) is about half as large as riverine transport of organic plus inorganic carbon to the ocean. Lakes are a small but potentially important conduit for carbon from terrestrial sources to the atmospheric sink.",
    url = "https://doi.org/10.1126/science.265.5178.1568",
    doi = "10.1126/science.265.5178.1568",
    openalex = "W2077975305",
    references = "doi101007978940111982531, doi10100797894011272023, doi101007bf00013449, doi101007bf00050748, doi101007bf01105015, doi101111j215334901982tb01837x, doi101126science2514991298, doi103402tellusav34i510834, doi104319lo19863130596, openalexw3119563525"
}

Abstract The terrestrial biosphere plays an important role in the global carbon cycle. In the 1994 Intergovernmental Panel Assessment on Climate Change (IPCC), an effort was made to improve the quantification of terrestrial exchanges and potential feedbacks from climate, changing CO 2, and other factors; this paper presents the key results from that assessment, together with expanded discussion. The carbon cycle is the fluxes of carbon among four main reservoirs: fossil carbon, the atmosphere, the oceans, and the terrestrial biosphere. Emissions of fossil carbon during the 1980s averaged 5.5 Gt y −1. During the same period, the atmosphere gained 3.2 Gt C y −1 and the oceans are believed to have absorbed 2.0 Gt C y −1. The regrowing forests of the Northern Hemisphere may have absorbed 0.5 Gt C y −1 during this period. Meanwhile, tropical deforestation is thought to have released an average 1.6 Gt C y −1 over the 1980s. While the fluxes among the four pools should balance, the average 198Ds values lead to a ‘missing sink’ of 1.4 Gt C y −1 Several processes, including forest regrowth, CO 2 fertilization of plant growth (c. 1.0 Gt C y −1), N deposition (c. 0.6 Gt C y −1), and their interactions, may account for the budget imbalance. However, it remains difficult to quantify the influences of these separate but interactive processes. Uncertainties in the individual numbers are large, and are themselves poorly quantified. This paper presents detail beyond the IPCC assessment on procedures used to approximate the flux uncertainties. Lack of knowledge about positive and negative feedbacks from the biosphere is a major limiting factor to credible simulations of future atmospheric CO 2 concentrations. Analyses of the atmospheric gradients of CO 2 and 13 CO 2 concentrations provide increasingly strong evidence for terrestrial sinks, potentially distributed between Northern Hemisphere and tropical regions, but conclusive detection in direct biomass and soil measurements remains elusive. Current regional‐to‐global terrestrial ecosystem models with coupled carbon and nitrogen cycles represent the effects of CO 2 fertilization differently, but all suggest longterm responses to CO 2 that are substantially smaller than potential leaf‐ or laboratory whole plant‐level responses. Analyses of emissions and biogeochemical fluxes consistent with eventual stabilization of atmospheric CO 2 concentrations are sensitive to the way in which biospheric feedbacks are modeled by c. 15%. Decisions about land use can have effects of 100s of Gt C over the next few centuries, with similarly significant effects on the atmosphere. Critical areas for future research are continued measurements and analyses of atmospheric data (CO 2 and 13 CO 2) to serve as large‐scale constraints, process studies of the scaling from the photosynthetic response to CO 2 to whole‐ecosystem carbon storage, and rigorous quantification of the effects of changing land use on carbon storage.

@article{doi101111j136524861995tb00008x,
    author = "Schimel, David",
    title = "Terrestrial ecosystems and the carbon cycle",
    year = "1995",
    journal = "Global Change Biology",
    abstract = "Abstract The terrestrial biosphere plays an important role in the global carbon cycle. In the 1994 Intergovernmental Panel Assessment on Climate Change (IPCC), an effort was made to improve the quantification of terrestrial exchanges and potential feedbacks from climate, changing CO 2, and other factors; this paper presents the key results from that assessment, together with expanded discussion. The carbon cycle is the fluxes of carbon among four main reservoirs: fossil carbon, the atmosphere, the oceans, and the terrestrial biosphere. Emissions of fossil carbon during the 1980s averaged 5.5 Gt y −1. During the same period, the atmosphere gained 3.2 Gt C y −1 and the oceans are believed to have absorbed 2.0 Gt C y −1. The regrowing forests of the Northern Hemisphere may have absorbed 0.5 Gt C y −1 during this period. Meanwhile, tropical deforestation is thought to have released an average 1.6 Gt C y −1 over the 1980s. While the fluxes among the four pools should balance, the average 198Ds values lead to a ‘missing sink’ of 1.4 Gt C y −1 Several processes, including forest regrowth, CO 2 fertilization of plant growth (c. 1.0 Gt C y −1), N deposition (c. 0.6 Gt C y −1), and their interactions, may account for the budget imbalance. However, it remains difficult to quantify the influences of these separate but interactive processes. Uncertainties in the individual numbers are large, and are themselves poorly quantified. This paper presents detail beyond the IPCC assessment on procedures used to approximate the flux uncertainties. Lack of knowledge about positive and negative feedbacks from the biosphere is a major limiting factor to credible simulations of future atmospheric CO 2 concentrations. Analyses of the atmospheric gradients of CO 2 and 13 CO 2 concentrations provide increasingly strong evidence for terrestrial sinks, potentially distributed between Northern Hemisphere and tropical regions, but conclusive detection in direct biomass and soil measurements remains elusive. Current regional‐to‐global terrestrial ecosystem models with coupled carbon and nitrogen cycles represent the effects of CO 2 fertilization differently, but all suggest longterm responses to CO 2 that are substantially smaller than potential leaf‐ or laboratory whole plant‐level responses. Analyses of emissions and biogeochemical fluxes consistent with eventual stabilization of atmospheric CO 2 concentrations are sensitive to the way in which biospheric feedbacks are modeled by c. 15\%. Decisions about land use can have effects of 100s of Gt C over the next few centuries, with similarly significant effects on the atmosphere. Critical areas for future research are continued measurements and analyses of atmospheric data (CO 2 and 13 CO 2) to serve as large‐scale constraints, process studies of the scaling from the photosynthetic response to CO 2 to whole‐ecosystem carbon storage, and rigorous quantification of the effects of changing land use on carbon storage.",
    url = "https://doi.org/10.1111/j.1365-2486.1995.tb00008.x",
    doi = "10.1111/j.1365-2486.1995.tb00008.x",
    openalex = "W1970527729",
    references = "broecker1979fate, doi101007bf00002772, doi10102991gb01778, doi10102993gb02725, doi101038361520a0, doi101038363234a0, doi101126science2064417409, doi101126science24749491431, doi101126science26051161905, doi101126science2635144185, doi102136sssaj199303615995005700010034x, doi1023071311067, openalexw1759145845"
}

Abstract The accuracy of Arctic lake chronologies has been assessed by measuring the 14 C activities of modern carbon sources and applying these isotopic mass balances to dating fossil lake materials. Small (<1 km 2) shallow (<25 m) Arctic lakes with watersheds <12 km 2 have soil and peat stratigraphic sections with 14 C activities ranging from 98 to 51% Modern. The 14 C activity of particulate organic carbon, dissolved organic carbon, and dissolved inorganic carbon from lake and stream waters ranges from 121 to 95% Modern. The sediment–water interface of the studied lakes shows consistent 14 C ages of ∼1000 14 C yr, although the 14 C activity of living aquatic vegetation is 115% Modern. Radiocarbon measurements of components of the lacustrine carbon pool imply that the ∼1000 14 C yr age of the sediment–water interface results from deposition of 14 C-depleted organic matter derived from the watershed.

@article{doi101006qres19960031,
    author = "Abbott, Mark B. and Stafford, Thomas W.",
    title = "Radiocarbon Geochemistry of Modern and Ancient Arctic Lake Systems, Baffin Island, Canada",
    year = "1996",
    journal = "Quaternary Research",
    abstract = "Abstract The accuracy of Arctic lake chronologies has been assessed by measuring the 14 C activities of modern carbon sources and applying these isotopic mass balances to dating fossil lake materials. Small (<1 km 2) shallow (<25 m) Arctic lakes with watersheds <12 km 2 have soil and peat stratigraphic sections with 14 C activities ranging from 98 to 51\% Modern. The 14 C activity of particulate organic carbon, dissolved organic carbon, and dissolved inorganic carbon from lake and stream waters ranges from 121 to 95\% Modern. The sediment–water interface of the studied lakes shows consistent 14 C ages of ∼1000 14 C yr, although the 14 C activity of living aquatic vegetation is 115\% Modern. Radiocarbon measurements of components of the lacustrine carbon pool imply that the ∼1000 14 C yr age of the sediment–water interface results from deposition of 14 C-depleted organic matter derived from the watershed.",
    url = "https://doi.org/10.1006/qres.1996.0031",
    doi = "10.1006/qres.1996.0031",
    openalex = "W2016895904",
    references = "doi101016016041209190291w, doi101017s0033822200040121, doi101017s0033822200056988, doi101038339532a0, doi101038361520a0, doi1010970001069419470400000001, doi101126science2514991298, doi101126science26551781568, doi101126science2665184416, doi1023071971875"
}

Atmospheric general circulation models used for climate simulation and weather forecasting require the fluxes of radiation, heat, water vapor, and momentum across the land-atmosphere interface to be specified. These fluxes are calculated by submodels called land surface parameterizations. Over the last 20 years, these parameterizations have evolved from simple, unrealistic schemes into credible representations of the global soil-vegetation-atmosphere transfer system as advances in plant physiological and hydrological research, advances in satellite data interpretation, and the results of large-scale field experiments have been exploited. Some modern schemes incorporate biogeochemical and ecological knowledge and, when coupled with advanced climate and ocean models, will be capable of modeling the biological and physical responses of the Earth system to global change, for example, increasing atmospheric carbon dioxide.

@article{doi101126science2755299502,
    author = "Sellers, P. J. and Dickinson, Robert E. and Randall, David A. and Betts, Alan K. and HALL, F. G. and Berry, Joseph A. and Collatz, G. J. and Denning, Scott and Mooney, Harold A. and Nobre, Carlos A. and Sato, N. and Field, Christopher B. and Henderson‐Sellers, A.",
    title = "Modeling the Exchanges of Energy, Water, and Carbon Between Continents and the Atmosphere",
    year = "1997",
    journal = "Science",
    abstract = "Atmospheric general circulation models used for climate simulation and weather forecasting require the fluxes of radiation, heat, water vapor, and momentum across the land-atmosphere interface to be specified. These fluxes are calculated by submodels called land surface parameterizations. Over the last 20 years, these parameterizations have evolved from simple, unrealistic schemes into credible representations of the global soil-vegetation-atmosphere transfer system as advances in plant physiological and hydrological research, advances in satellite data interpretation, and the results of large-scale field experiments have been exploited. Some modern schemes incorporate biogeochemical and ecological knowledge and, when coupled with advanced climate and ocean models, will be capable of modeling the biological and physical responses of the Earth system to global change, for example, increasing atmospheric carbon dioxide.",
    url = "https://doi.org/10.1126/science.275.5299.502",
    doi = "10.1126/science.275.5299.502",
    openalex = "W2157144502",
    references = "doi101016016041209190291w, doi101029rg012i003p00447"
}

The focus of this paper is the conversion of radiocarbon ages to calibrated (cal) ages for the interval 24,000–0 cal BP (Before Present, 0 cal BP = AD 1950), based upon a sample set of dendrochronologically dated tree rings, uranium-thorium dated corals, and varve-counted marine sediment. The 14 C age–cal age information, produced by many laboratories, is converted to Δ 14 C profiles and calibration curves, for the atmosphere as well as the oceans. We discuss offsets in measured l4 C ages and the errors therein, regional 14 C age differences, tree–coral 14 C age comparisons and the time dependence of marine reservoir ages, and evaluate decadal vs. single-year 14 C results. Changes in oceanic deepwater circulation, especially for the 16,000–11,000 cal BP interval, are reflected in the Δ 14 C values of INTCAL98.

@article{doi101017s0033822200019123,
    author = "Stuiver, Minze and Reimer, Paula and Bard, Édouard and Beck, J and Burr, George S. and Hughen, Konrad A and Kromer, Bernd and McCormac, Gerry and van der Plicht, J. and Spurk, Marco",
    title = "INTCAL98 Radiocarbon Age Calibration, 24,000–0 cal BP",
    year = "1998",
    journal = "Radiocarbon",
    abstract = "The focus of this paper is the conversion of radiocarbon ages to calibrated (cal) ages for the interval 24,000–0 cal BP (Before Present, 0 cal BP = AD 1950), based upon a sample set of dendrochronologically dated tree rings, uranium-thorium dated corals, and varve-counted marine sediment. The 14 C age–cal age information, produced by many laboratories, is converted to Δ 14 C profiles and calibration curves, for the atmosphere as well as the oceans. We discuss offsets in measured l4 C ages and the errors therein, regional 14 C age differences, tree–coral 14 C age comparisons and the time dependence of marine reservoir ages, and evaluate decadal vs. single-year 14 C results. Changes in oceanic deepwater circulation, especially for the 16,000–11,000 cal BP interval, are reflected in the Δ 14 C values of INTCAL98.",
    url = "https://doi.org/10.1017/s0033822200019123",
    doi = "10.1017/s0033822200019123",
    openalex = "W1927648166",
    references = "doi101017s0033822200003672, doi101017s0033822200013904, doi101017s0033822200019172, doi101038345405a0, doi101126science27953541187, openalexw1928750549"
}

Single-year and decadal radiocarbon tree-ring ages are tabulated and discussed in terms of 14 C age calibration. The single-year data form the basis of a detailed 14 C age calibration curve for the cal ad 1510–1954 interval (“cal” denotes calibrated). The Seattle decadal data set (back to 11,617 cal BP, with 0 BP = ad 1950) is a component of the integrated decadal INTCAL98 14 C age curve (Stuiver et al. 1998). Atmospheric 14 C ages can be transformed into 14 C ages of the global ocean using a carbon reservoir model. INTCAL98 14 C ages, used for these calculations, yield global ocean 14 C ages differing slightly from previously published ones (Stuiver and Braziunas 1993b). We include discussions of offsets, error multipliers, regional 14 C age differences and marine 14 C age response to oceanic and atmospheric forcing.

@article{doi101017s0033822200019172,
    author = "Stuiver, Minze and Reimer, Paula and Braziunas, Thomas F.",
    title = "High-Precision Radiocarbon Age Calibration for Terrestrial and Marine Samples",
    year = "1998",
    journal = "Radiocarbon",
    abstract = "Single-year and decadal radiocarbon tree-ring ages are tabulated and discussed in terms of 14 C age calibration. The single-year data form the basis of a detailed 14 C age calibration curve for the cal ad 1510–1954 interval (“cal” denotes calibrated). The Seattle decadal data set (back to 11,617 cal BP, with 0 BP = ad 1950) is a component of the integrated decadal INTCAL98 14 C age curve (Stuiver et al. 1998). Atmospheric 14 C ages can be transformed into 14 C ages of the global ocean using a carbon reservoir model. INTCAL98 14 C ages, used for these calculations, yield global ocean 14 C ages differing slightly from previously published ones (Stuiver and Braziunas 1993b). We include discussions of offsets, error multipliers, regional 14 C age differences and marine 14 C age response to oceanic and atmospheric forcing.",
    url = "https://doi.org/10.1017/s0033822200019172",
    doi = "10.1017/s0033822200019172",
    openalex = "W1508328190",
    references = "doi101017s0033822200003672, doi101017s0033822200013783, doi101017s0033822200013874, doi101017s0033822200013904, doi101017s0033822200019123, doi101017s0033822200060264, doi101029pa003i006p00635, doi101126science2605110962, doi101177095968369300300401, openalexw1928750549"
}

More than 250 carbon-14 accelerator mass spectrometry dates of terrestrial macrofossils from annually laminated sediments from Lake Suigetsu (Japan) provide a first atmospheric calibration for almost the total range of the radiocarbon method (45,000 years before the present). The results confirm the (recently revised) floating German pine chronology and are consistent with data from European and marine varved sediments, and combined uranium-thorium and carbon-14 dating of corals up to the Last Glacial Maximum. The data during the Glacial show large fluctuations in the atmospheric carbon-14 content, related to changes in global environment and in cosmogenic isotope production.

@article{doi101126science27953541187,
    author = "Kitagawa, Hiroyuki and van der Plicht, J.",
    title = "Atmospheric Radiocarbon Calibration to 45,000 yr B.P.: Late Glacial Fluctuations and Cosmogenic Isotope Production",
    year = "1998",
    journal = "Science",
    abstract = "More than 250 carbon-14 accelerator mass spectrometry dates of terrestrial macrofossils from annually laminated sediments from Lake Suigetsu (Japan) provide a first atmospheric calibration for almost the total range of the radiocarbon method (45,000 years before the present). The results confirm the (recently revised) floating German pine chronology and are consistent with data from European and marine varved sediments, and combined uranium-thorium and carbon-14 dating of corals up to the Last Glacial Maximum. The data during the Glacial show large fluctuations in the atmospheric carbon-14 content, related to changes in global environment and in cosmogenic isotope production.",
    url = "https://doi.org/10.1126/science.279.5354.1187",
    doi = "10.1126/science.279.5354.1187",
    openalex = "W2138883883",
    references = "doi1010160012821x96001215, doi101016s0012821x97000708, doi10102997jc01265, doi101038329408a0, doi101038345405a0, doi101038356757a0, doi101038382241a0, doi101111j150238851989tb00381x, doi101126science2605110962, doi101126science27452901155"
}

Many freshwater lakes are supersaturated in CO 2 with respect to the atmosphere. This concentration gradient implies a net flux of CO 2 from the water to the air. The actual rate of gas exchange is governed by both this concentration gradient and the gas transfer coefficient, k. To directly measure k, we added the chemically and biologically inert gas, sulfur hexaflouride (SF 6), to the epilimnion of Mirror Lake, New Hampshire, a small (15 ha), low‐wind softwater lake. k was independent of wind speed over the 50‐d summer stratification period and averaged 2.65 ± 0.12 cm h −1 (95% CI; normalized to a Schmidt number of 600); k 800, was better correlated to precipitation events than it was to wind speed. Our data support the idea that gas exchange across the air‐water interface is largely independent of wind at low wind speeds. The surface water of Mirror Lake was persistently supersaturated in CO, with respect to the atmosphere. During a 3.5‐‐year period the partial pressure of CO 2 in the surface waters of the lake averaged 726 ± 39 µatm (95% CI) and showed substantial seasonal variation (360–2,000 patm). Diel and day‐to‐day variation in CO 2 were very small compared to the CO 2 pool. We combined our estimates of k with weekly measurements of the partial pressure of CO 2 to estimate CO 2 gas exchange in the lake. Mirror Lake released from 26 to 50 g C m −2 to the atmosphere each year, depending on the method of calculating k. Atmospheric CO 2 exchange is a large term in the C economy of the lake—the most conservative gas flux estimate is about four times as large as outflow plus seepage of total dissolved inorganic carbon and 1.5 times as large as the export of dissolved organic C from the lake.

@article{doi104319lo19984340647,
    author = "Cole, Jonathan J. and Caraco, Nina F.",
    title = "Atmospheric exchange of carbon dioxide in a low‐wind oligotrophic lake measured by the addition of SF 6",
    year = "1998",
    journal = "Limnology and Oceanography",
    abstract = "Many freshwater lakes are supersaturated in CO 2 with respect to the atmosphere. This concentration gradient implies a net flux of CO 2 from the water to the air. The actual rate of gas exchange is governed by both this concentration gradient and the gas transfer coefficient, k. To directly measure k, we added the chemically and biologically inert gas, sulfur hexaflouride (SF 6), to the epilimnion of Mirror Lake, New Hampshire, a small (15 ha), low‐wind softwater lake. k was independent of wind speed over the 50‐d summer stratification period and averaged 2.65 ± 0.12 cm h −1 (95\% CI; normalized to a Schmidt number of 600); k 800, was better correlated to precipitation events than it was to wind speed. Our data support the idea that gas exchange across the air‐water interface is largely independent of wind at low wind speeds. The surface water of Mirror Lake was persistently supersaturated in CO, with respect to the atmosphere. During a 3.5‐‐year period the partial pressure of CO 2 in the surface waters of the lake averaged 726 ± 39 µatm (95\% CI) and showed substantial seasonal variation (360–2,000 patm). Diel and day‐to‐day variation in CO 2 were very small compared to the CO 2 pool. We combined our estimates of k with weekly measurements of the partial pressure of CO 2 to estimate CO 2 gas exchange in the lake. Mirror Lake released from 26 to 50 g C m −2 to the atmosphere each year, depending on the method of calculating k. Atmospheric CO 2 exchange is a large term in the C economy of the lake—the most conservative gas flux estimate is about four times as large as outflow plus seepage of total dissolved inorganic carbon and 1.5 times as large as the export of dissolved organic C from the lake.",
    url = "https://doi.org/10.4319/lo.1998.43.4.0647",
    doi = "10.4319/lo.1998.43.4.0647",
    openalex = "W2016743751",
    references = "doi101126science2514991298, doi101126science26551781568, doi103402tellusav26i129733"
}

@article{s239b1ec9f7ccb9de65bd8549b94d47700f257fa1d,
    author = "Richards, D. and Beck, J. and Donahue, D. and Smart, P. and Edwards, R.",
    title = "Thorium-230 and Carbon-14 Dating of Speleothems from the Bahamas: Implications for Calibration of the Radiocarbon Timescale",
    year = "1999",
    journal = "nag",
    url = "https://www.semanticscholar.org/paper/39b1ec9f7ccb9de65bd8549b94d47700f257fa1d",
    is_oa = "true",
    openalex = "W3027169300",
    semanticscholar_citation_count = "2",
    semanticscholar_id = "39b1ec9f7ccb9de65bd8549b94d47700f257fa1d"
}

Climate on Earth strongly depends on the radiative balance of its atmosphere, and thus, on the abundance of the radiatively active greenhouse gases. Largely due to human activities since the Industrial Revolution, the atmospheric burden of many greenhouse gases has increased dramatically. Direct measurements during the last decades and analysis of ancient air trapped in ice from polar regions allow the quantification of the change in these trace gas concentrations in the atmosphere. From a presumably “undisturbed” preindustrial situation several hundred years ago until today, the CO 2 mixing ratio increased by almost 30% (Figure 1a) (Neftel et al. 1985; Conway et al. 1994; Etheridge et al. 1996). In the last decades this increase has been nearly exponential, leading to a global mean CO 2 mixing ratio of almost 370 ppm at the turn of the millennium (Keeling and Whorf 1999).

@article{doi101017s0033822200053066,
    author = "Levin, Ingeborg and Hesshaimer, Vago",
    title = "Radiocarbon – A Unique Tracer of Global Carbon Cycle Dynamics",
    year = "2000",
    journal = "Radiocarbon",
    abstract = "Climate on Earth strongly depends on the radiative balance of its atmosphere, and thus, on the abundance of the radiatively active greenhouse gases. Largely due to human activities since the Industrial Revolution, the atmospheric burden of many greenhouse gases has increased dramatically. Direct measurements during the last decades and analysis of ancient air trapped in ice from polar regions allow the quantification of the change in these trace gas concentrations in the atmosphere. From a presumably “undisturbed” preindustrial situation several hundred years ago until today, the CO 2 mixing ratio increased by almost 30\% (Figure 1a) (Neftel et al. 1985; Conway et al. 1994; Etheridge et al. 1996). In the last decades this increase has been nearly exponential, leading to a global mean CO 2 mixing ratio of almost 370 ppm at the turn of the millennium (Keeling and Whorf 1999).",
    url = "https://doi.org/10.1017/s0033822200053066",
    doi = "10.1017/s0033822200053066",
    openalex = "W1945170571",
    references = "doi1010079789400947382, doi10100797894009473825, doi101017s0033822200003672, doi10102992jc00188, doi10102994jd01951, doi10102995jd03410, doi101038365119a0, doi103402tellusav27i29900, doi105860choice333969, openalexw1928750549"
}

Radiocarbon data from the Cariaco Basin provide calibration of the carbon-14 time scale across the period of deglaciation (15,000 to 10, 000 years ago) with resolution available previously only from Holocene tree rings. Reconstructed changes in atmospheric carbon-14 are larger than previously thought, with the largest change occurring simultaneously with the sudden climatic cooling of the Younger Dryas event. Carbon-14 and published beryllium-10 data together suggest that concurrent climate and carbon-14 changes were predominantly the result of abrupt shifts in deep ocean ventilation.

@article{doi101126science29054981951,
    author = "Hughen, Konrad A and Southon, John and Lehman, Scott J. and Overpeck, Jonathan T.",
    title = "Synchronous Radiocarbon and Climate Shifts During the Last Deglaciation",
    year = "2000",
    journal = "Science",
    abstract = "Radiocarbon data from the Cariaco Basin provide calibration of the carbon-14 time scale across the period of deglaciation (15,000 to 10, 000 years ago) with resolution available previously only from Holocene tree rings. Reconstructed changes in atmospheric carbon-14 are larger than previously thought, with the largest change occurring simultaneously with the sudden climatic cooling of the Younger Dryas event. Carbon-14 and published beryllium-10 data together suggest that concurrent climate and carbon-14 changes were predominantly the result of abrupt shifts in deep ocean ventilation.",
    url = "https://doi.org/10.1126/science.290.5498.1951",
    doi = "10.1126/science.290.5498.1951",
    openalex = "W1999080586"
}

Radiocarbon data from soil organic matter and soil respiration provide powerful constraints for determining carbon dynamics and thereby the magnitude and timing of soil carbon response to global change. In this paper, data from three sites representing well-drained soils in boreal, temperate, and tropical forests are used to illustrate the methods for using radiocarbon to determine the turnover times of soil organic matter and to partition soil respiration. For these sites, the average age of bulk carbon in detrital and Oh/A-horizon organic carbon ranges from 200 to 1200 yr. In each case, this mass-weighted average includes components such as relatively undecomposed leaf, root, and moss litter with much shorter turnover times, and humified or mineral-associated organic matter with much longer turnover times. The average age of carbon in organic matter is greater than the average age predicted for CO2 produced by its decomposition (30, 8, and 3 yr for boreal, temperate, and tropical soil), or measured in total soil respiration (16, 3, and 1 yr). Most of the CO2 produced during decomposition is derived from relatively short-lived soil organic matter (SOM) components that do not represent a large component of the standing stock of soil organic matter. Estimates of soil carbon turnover obtained by dividing C stocks by heterotrophic respiration fluxes, or from radiocarbon measurements of bulk SOM, are biased to longer time scales of C cycling. Failure to account for the heterogeneity of soil organic matter will result in underestimation of the short-term response and overestimation of the long-term response of soil C storage to future changes in inputs or decomposition. Comparison of the 14C in soil respiration with soil organic matter in temperate and boreal forest sites indicates a significant contribution from decomposition of organic matter fixed >2 yr but <30 yr ago. Tropical soil respiration is dominated by C fixed <1 yr ago. Monitoring the 14C signature of CO2 emitted from soils give clues as to the causes of seasonal and interannual variability in soil respiration in these systems.

@article{doi1018901051076120000100399aosoma20co2,
    author = "Trumbore, Susan",
    title = "AGE OF SOIL ORGANIC MATTER AND SOIL RESPIRATION: RADIOCARBON CONSTRAINTS ON BELOWGROUND C DYNAMICS",
    year = "2000",
    journal = "Ecological Applications",
    abstract = "Radiocarbon data from soil organic matter and soil respiration provide powerful constraints for determining carbon dynamics and thereby the magnitude and timing of soil carbon response to global change. In this paper, data from three sites representing well-drained soils in boreal, temperate, and tropical forests are used to illustrate the methods for using radiocarbon to determine the turnover times of soil organic matter and to partition soil respiration. For these sites, the average age of bulk carbon in detrital and Oh/A-horizon organic carbon ranges from 200 to 1200 yr. In each case, this mass-weighted average includes components such as relatively undecomposed leaf, root, and moss litter with much shorter turnover times, and humified or mineral-associated organic matter with much longer turnover times. The average age of carbon in organic matter is greater than the average age predicted for CO2 produced by its decomposition (30, 8, and 3 yr for boreal, temperate, and tropical soil), or measured in total soil respiration (16, 3, and 1 yr). Most of the CO2 produced during decomposition is derived from relatively short-lived soil organic matter (SOM) components that do not represent a large component of the standing stock of soil organic matter. Estimates of soil carbon turnover obtained by dividing C stocks by heterotrophic respiration fluxes, or from radiocarbon measurements of bulk SOM, are biased to longer time scales of C cycling. Failure to account for the heterogeneity of soil organic matter will result in underestimation of the short-term response and overestimation of the long-term response of soil C storage to future changes in inputs or decomposition. Comparison of the 14C in soil respiration with soil organic matter in temperate and boreal forest sites indicates a significant contribution from decomposition of organic matter fixed >2 yr but <30 yr ago. Tropical soil respiration is dominated by C fixed <1 yr ago. Monitoring the 14C signature of CO2 emitted from soils give clues as to the causes of seasonal and interannual variability in soil respiration in these systems.",
    url = "https://doi.org/10.1890/1051-0761(2000)010[0399:aosoma]2.0.co;2",
    doi = "10.1890/1051-0761(2000)010[0399:aosoma]2.0.co;2",
    openalex = "W2108732658"
}

This paper covers three different methods of matching radiocarbon dates to the ‘wiggles’ of the calibration curve in those situations where the age difference between the 14 C dates is known. These methods are most often applied to tree-ring sequences. The simplest approach is to use a classical Chi-squared fit of the 14 C data to the 14 C curve. This gives the calendar date where the data fit best and allows tests of how good the fit is. The only drawback of this method is that it is difficult to ascertain the uncertainty in the date found in this way. An extension of this technique uses a Monte-Carlo simulation to sample possible 14 C concentrations consistent with the measurement made and for each of these possibilities performs a Chi-squared fit. This method yields a distribution of values in the calendrical time-scale, from which the overall dating uncertainty can be derived. A third, rather different approach, based on Bayesian statistics, calculates the relative likelihood of each possible calendar year fit. This can then be used to calculate a range of most likely dates in a similar way to the probability method of 14 C calibration. The theories underlying all three methods are discussed in this paper and a comparison made for the fitting of specific model sequences. All three methods are found to give consistent results and the application of any one of them depends on the nature of the scientific question being addressed.

@article{doi101017s0033822200038248,
    author = "Ramsey, Christopher Bronk and van der Plicht, J. and Weninger, Bernhard",
    title = "‘Wiggle Matching’ Radiocarbon Dates",
    year = "2001",
    journal = "Radiocarbon",
    abstract = "This paper covers three different methods of matching radiocarbon dates to the ‘wiggles’ of the calibration curve in those situations where the age difference between the 14 C dates is known. These methods are most often applied to tree-ring sequences. The simplest approach is to use a classical Chi-squared fit of the 14 C data to the 14 C curve. This gives the calendar date where the data fit best and allows tests of how good the fit is. The only drawback of this method is that it is difficult to ascertain the uncertainty in the date found in this way. An extension of this technique uses a Monte-Carlo simulation to sample possible 14 C concentrations consistent with the measurement made and for each of these possibilities performs a Chi-squared fit. This method yields a distribution of values in the calendrical time-scale, from which the overall dating uncertainty can be derived. A third, rather different approach, based on Bayesian statistics, calculates the relative likelihood of each possible calendar year fit. This can then be used to calculate a range of most likely dates in a similar way to the probability method of 14 C calibration. The theories underlying all three methods are discussed in this paper and a comparison made for the fitting of specific model sequences. All three methods are found to give consistent results and the application of any one of them depends on the nature of the scientific question being addressed.",
    url = "https://doi.org/10.1017/s0033822200038248",
    doi = "10.1017/s0033822200038248",
    openalex = "W2112825244"
}

To compare the effectiveness of different pasture species in restoring soil quality, changes in concentration and quality of soil organic carbon (C) were measured in the surface 10 cm of an Oxic Paleustalf (red earth) in the semiarid area of New South Wales, Australia, at the end of 4 years under lucerne (Medicago sativa cv. Trifecta), Consol lovegrass (Eragrostis curvula), and barrel medic (Medicago truncutulata cv sephi). Before the investigation, the soil had been degraded by 50 years of cropping. Soil samples were analyzed for water stable aggregation, mineralizable N, and C by three procedures: Total carbon (C) by dry combustion, oxidizible C by potassium permanganate, and oxidizible C by potassium dichromate/sulphuric acid with varying concentrations of acid. Higher dry matter production caused lucerne to be was more effective than barrel medic in increasing soil organic carbon concentration. Compared with fallow plots, total soil organic carbon concentration increased by 16, 26, and 11%, respectively, in the Consol lovegrass, lucerne, and barrel medic treatments. Nevertheless, even in the case of lucerne, the 26% increase in organic carbon in the 0-10-cm layer at the end of 4 years (7.87 vs. 9.88 g/kg) represented only 15% of the total loss in organic carbon after 50 years of cropping. Most (78-92%) of the organic carbon increases under the various pastures were of the more labile forms, as indicated by their removal under much milder oxidizing conditions than those recommended in the standard methods for organic carbon determination. Significant improvements in structural stability and nitrogen availability were detected in the perennial pasture soils. Our results suggested that the amount of organic carbon oxidizible by a modified Walkley-Black method, which involves using only half the amount of sulphuric acid, is a more sensitive indicator of the improvement in soil quality parameters under investigation, namely increases in mineralizable nitrogen and water stable aggregation. Further research is needed to verify these findings over a range of soil types and agroecosystems.

@article{doi1010970001069420010100000009,
    author = "Chan, K. Y. and Bowman, A. M. and Oates, Albert",
    title = "OXIDIZIBLE ORGANIC CARBON FRACTIONS AND SOIL QUALITY CHANGES IN AN OXIC PALEUSTALF UNDER DIFFERENT PASTURE LEYS",
    year = "2001",
    journal = "Soil Science",
    abstract = "To compare the effectiveness of different pasture species in restoring soil quality, changes in concentration and quality of soil organic carbon (C) were measured in the surface 10 cm of an Oxic Paleustalf (red earth) in the semiarid area of New South Wales, Australia, at the end of 4 years under lucerne (Medicago sativa cv. Trifecta), Consol lovegrass (Eragrostis curvula), and barrel medic (Medicago truncutulata cv sephi). Before the investigation, the soil had been degraded by 50 years of cropping. Soil samples were analyzed for water stable aggregation, mineralizable N, and C by three procedures: Total carbon (C) by dry combustion, oxidizible C by potassium permanganate, and oxidizible C by potassium dichromate/sulphuric acid with varying concentrations of acid. Higher dry matter production caused lucerne to be was more effective than barrel medic in increasing soil organic carbon concentration. Compared with fallow plots, total soil organic carbon concentration increased by 16, 26, and 11\%, respectively, in the Consol lovegrass, lucerne, and barrel medic treatments. Nevertheless, even in the case of lucerne, the 26\% increase in organic carbon in the 0-10-cm layer at the end of 4 years (7.87 vs. 9.88 g/kg) represented only 15\% of the total loss in organic carbon after 50 years of cropping. Most (78-92\%) of the organic carbon increases under the various pastures were of the more labile forms, as indicated by their removal under much milder oxidizing conditions than those recommended in the standard methods for organic carbon determination. Significant improvements in structural stability and nitrogen availability were detected in the perennial pasture soils. Our results suggested that the amount of organic carbon oxidizible by a modified Walkley-Black method, which involves using only half the amount of sulphuric acid, is a more sensitive indicator of the improvement in soil quality parameters under investigation, namely increases in mineralizable nitrogen and water stable aggregation. Further research is needed to verify these findings over a range of soil types and agroecosystems.",
    url = "https://doi.org/10.1097/00010694-200101000-00009",
    doi = "10.1097/00010694-200101000-00009",
    openalex = "W2032808495",
    references = "doi1010970001069419470400000001"
}

FLUXNET is a global network of micrometeorological flux measurement sites that measure the exchanges of carbon dioxide, water vapor, and energy between the biosphere and atmosphere. At present over 140 sites are operating on a long-term and continuous basis. Vegetation under study includes temperate conifer and broadleaved (deciduous and evergreen) forests, tropical and boreal forests, crops, grasslands, chaparral, wetlands, and tundra. Sites exist on five continents and their latitudinal distribution ranges from 70°N to 30°S. FLUXNET has several primary functions. First, it provides infrastructure for compiling, archiving, and distributing carbon, water, and energy flux measurement, and meteorological, plant, and soil data to the science community. (Data and site information are available online at the FLUXNET Web site, http://www-eosdis.ornl.gov/FLUXNET/.) Second, the project supports calibration and flux intercomparison activities. This activity ensures that data from the regional networks are intercomparable. And third, FLUXNET supports the synthesis, discussion, and communication of ideas and data by supporting project scientists, workshops, and visiting scientists. The overarching goal is to provide information for validating computations of net primary productivity, evaporation, and energy absorption that are being generated by sensors mounted on the NASA Terra satellite. Data being compiled by FLUXNET are being used to quantify and compare magnitudes and dynamics of annual ecosystem carbon and water balances, to quantify the response of stand-scale carbon dioxide and water vapor flux densities to controlling biotic and abiotic factors, and to validate a hierarchy of soil–plant–atmosphere trace gas exchange models. Findings so far include 1) net CO2 exchange of temperate broadleaved forests increases by about 5.7 g C m−2 day−1 for each additional day that the growing season is extended; 2) the sensitivity of net ecosystem CO2 exchange to sunlight doubles if the sky is cloudy rather than clear; 3) the spectrum of CO2 flux density exhibits peaks at timescales of days, weeks, and years, and a spectral gap exists at the month timescale; 4) the optimal temperature of net CO2 exchange varies with mean summer temperature; and 5) stand age affects carbon dioxide and water vapor flux densities.

@article{doi1011751520047720010822415fantts23co2,
    author = "Baldocchi, Dennis and Falge, Eva and Gu, Lianhong and Olson, Richard and Hollinger, David Y. and Running, S. W. and Anthoni, Peter and Bernhofer, Christian and Davis, K. J. and Evans, Robert S. and Fuentes, José D. and Goldstein, Allen H. and Katul, Gabriel G. and Law, B. E. and Lee, Xuhui and Malhi, Yadvinder and Meyers, Tilden P. and Munger, J. William and Oechel, Walter C. and Paw, Kyaw Tha and Pilegaard, Kim and Schmid, Hans Peter and Valentini, Riccardo and Verma, Shashi B. and Vesala, Timo and Wilson, Kell and Wofsy, S. C.",
    title = "FLUXNET: A New Tool to Study the Temporal and Spatial Variability of Ecosystem–Scale Carbon Dioxide, Water Vapor, and Energy Flux Densities",
    year = "2001",
    journal = "Bulletin of the American Meteorological Society",
    abstract = "FLUXNET is a global network of micrometeorological flux measurement sites that measure the exchanges of carbon dioxide, water vapor, and energy between the biosphere and atmosphere. At present over 140 sites are operating on a long-term and continuous basis. Vegetation under study includes temperate conifer and broadleaved (deciduous and evergreen) forests, tropical and boreal forests, crops, grasslands, chaparral, wetlands, and tundra. Sites exist on five continents and their latitudinal distribution ranges from 70°N to 30°S. FLUXNET has several primary functions. First, it provides infrastructure for compiling, archiving, and distributing carbon, water, and energy flux measurement, and meteorological, plant, and soil data to the science community. (Data and site information are available online at the FLUXNET Web site, http://www-eosdis.ornl.gov/FLUXNET/.) Second, the project supports calibration and flux intercomparison activities. This activity ensures that data from the regional networks are intercomparable. And third, FLUXNET supports the synthesis, discussion, and communication of ideas and data by supporting project scientists, workshops, and visiting scientists. The overarching goal is to provide information for validating computations of net primary productivity, evaporation, and energy absorption that are being generated by sensors mounted on the NASA Terra satellite. Data being compiled by FLUXNET are being used to quantify and compare magnitudes and dynamics of annual ecosystem carbon and water balances, to quantify the response of stand-scale carbon dioxide and water vapor flux densities to controlling biotic and abiotic factors, and to validate a hierarchy of soil–plant–atmosphere trace gas exchange models. Findings so far include 1) net CO2 exchange of temperate broadleaved forests increases by about 5.7 g C m−2 day−1 for each additional day that the growing season is extended; 2) the sensitivity of net ecosystem CO2 exchange to sunlight doubles if the sky is cloudy rather than clear; 3) the spectrum of CO2 flux density exhibits peaks at timescales of days, weeks, and years, and a spectral gap exists at the month timescale; 4) the optimal temperature of net CO2 exchange varies with mean summer temperature; and 5) stand age affects carbon dioxide and water vapor flux densities.",
    url = "https://doi.org/10.1175/1520-0477(2001)082<2415:fantts>2.3.co;2",
    doi = "10.1175/1520-0477(2001)082<2415:fantts>2.3.co;2",
    openalex = "W2338049369",
    references = "doi1010160168192395022481, doi101016s0065250408600185, doi101016s0168192300002252, doi10103835009084, doi101038386698a0, doi101111j136524861996tb00070x, doi101126science24749491431, doi101146annurevarplant481609, doi1023071941631, doi105860choice320998"
}

From 1950 to 1963 atmospheric testing of thermonuclear devices produced elevated levels of artificial carbon-14 in the atmosphere. Terrestrial organic material from that time period displays carbon-14 activity nearly twice the pre-1950 levels. Measurement of the carbon-14 activity within organic specimens from forensic cases can reveal if the material dates before or after about 1955. Such information can prove important in some cases in determining if the material is sufficiently recent to be of forensic concern. Application of this technique to an unidentified human skeleton from the American southwest is discussed.

@article{doi101520jfs15147j,
    author = "Ubelaker, Douglas H.",
    title = "Artificial Radiocarbon as an Indicator of Recent Origin of Organic Remains in Forensic Cases",
    year = "2001",
    journal = "Journal of Forensic Sciences",
    abstract = "From 1950 to 1963 atmospheric testing of thermonuclear devices produced elevated levels of artificial carbon-14 in the atmosphere. Terrestrial organic material from that time period displays carbon-14 activity nearly twice the pre-1950 levels. Measurement of the carbon-14 activity within organic specimens from forensic cases can reveal if the material dates before or after about 1955. Such information can prove important in some cases in determining if the material is sufficiently recent to be of forensic concern. Application of this technique to an unidentified human skeleton from the American southwest is discussed.",
    url = "https://doi.org/10.1520/jfs15147j",
    doi = "10.1520/jfs15147j",
    openalex = "W1808471252"
}

Abstract: Optically stimulated luminescence (OSL) dating of light-exposed sediments is used increasingly as a mean of establishing a sediment deposition chronology in a wide variety of late Quaternary studies. There has been considerable technological development in the last few years in instrumentation, in the preferred mineral, and in various measurement proto-cols. New approaches to the latter, especially with the introduction of the single-aliquot regenerative-dose (SAR) protocol, have given rise to an increasing number of ages in the li-terature based on the OSL signals from quartz. This paper examines the reliability of these results by reviewing both published and unpublished SAR quartz ages for which some independent age control exists. It first discusses studies of modern (zero age) sediments, and the implications of these results for the importance of incomplete bleaching, especially in water-lain sediments, i.e. sediments for which the initial light exposure is expected to have been insufficient to reduce the apparent dose at deposition to a negligible fraction of the final burial dose. It then compares OSL and independent ages derived from various types of sedi-ments, including aeolian, fluvial/lacustrine, marine and glacio-fluvial/lacustrine. It is concluded that, in general, the ages are accurate, in that there is no evidence for systematic errors over an age range from the last century to at least 350 ka. Nevertheless, the published uncertain-ties of a small fraction of OSL ages are probably underestimated. We conclude that OSL dating of quartz is a reliable chronological tool; this conclusion is reflected in its growing popularity in Quaternary studies. Key words: OSL DATING,

@misc{openalexw1492524608,
    author = "Murray, Andrew and Olley, Jon",
    title = "PRECISION AND ACCURACY IN THE OPTICALLY STIMULATED LUMINESCENCE DATING OF SEDIMENTARY QUARTZ: A STATUS REVIEW",
    year = "2002",
    abstract = "Abstract: Optically stimulated luminescence (OSL) dating of light-exposed sediments is used increasingly as a mean of establishing a sediment deposition chronology in a wide variety of late Quaternary studies. There has been considerable technological development in the last few years in instrumentation, in the preferred mineral, and in various measurement proto-cols. New approaches to the latter, especially with the introduction of the single-aliquot regenerative-dose (SAR) protocol, have given rise to an increasing number of ages in the li-terature based on the OSL signals from quartz. This paper examines the reliability of these results by reviewing both published and unpublished SAR quartz ages for which some independent age control exists. It first discusses studies of modern (zero age) sediments, and the implications of these results for the importance of incomplete bleaching, especially in water-lain sediments, i.e. sediments for which the initial light exposure is expected to have been insufficient to reduce the apparent dose at deposition to a negligible fraction of the final burial dose. It then compares OSL and independent ages derived from various types of sedi-ments, including aeolian, fluvial/lacustrine, marine and glacio-fluvial/lacustrine. It is concluded that, in general, the ages are accurate, in that there is no evidence for systematic errors over an age range from the last century to at least 350 ka. Nevertheless, the published uncertain-ties of a small fraction of OSL ages are probably underestimated. We conclude that OSL dating of quartz is a reliable chronological tool; this conclusion is reflected in its growing popularity in Quaternary studies. Key words: OSL DATING,",
    openalex = "W1492524608",
    references = "doi101017s0033822200018397, doi101126science27953541187"
}

The global distribution of C 3 and C 4 plants is required for accurately simulating exchanges of CO 2, water, and energy between the land surface and atmosphere. It is also important to know the C 3 /C 4 distribution for simulations of the carbon isotope composition of atmospheric CO 2 owing to the distinct fractionations displayed by each photosynthetic type. Large areas of the land surface are spatial and temporal mosaics of both photosynthetic types. We developed an approach for capturing this heterogeneity by combining remote sensing products, physiological modeling, a spatial distribution of global crop fractions, and national harvest area data for major crop types. Our C 3 /C 4 distribution predicts the global coverage of C 4 vegetation to be 18.8 million km 2, while C 3 vegetation covers 87.4 million km 2. We incorporated our distribution into the SiB2 model and simulated carbon fluxes for each photosynthetic type. The gross primary production (GPP) of C 4 plants is 35.3 Pg C yr −1, or ∼23% of total GPP, while that of C 3 plants is 114.7 Pg C yr −1. The assimilation‐weighted terrestrial discrimination against 13 CO 2 is −16.5‰. If the terrestrial component of the carbon sink is proportional to GPP, this implies a net uptake of 2.4 Pg C yr −1 on land and 1.4 Pg C yr −1 in the ocean using a 13 C budgeting approach and average carbon cycle parameter values for the 1990s. We also simulated the biomass of each photosynthetic type using the CASA model. The simulated biomass values of C 3 and C 4 vegetation are 389.3 and 18.6 Pg C, respectively.

@article{doi1010292001gb001807,
    author = "Still, Christopher J. and Berry, Joseph A. and Collatz, G. J. and DeFries, Ruth",
    title = "Global distribution of C 3 and C 4 vegetation: Carbon cycle implications",
    year = "2003",
    journal = "Global Biogeochemical Cycles",
    abstract = "The global distribution of C 3 and C 4 plants is required for accurately simulating exchanges of CO 2, water, and energy between the land surface and atmosphere. It is also important to know the C 3 /C 4 distribution for simulations of the carbon isotope composition of atmospheric CO 2 owing to the distinct fractionations displayed by each photosynthetic type. Large areas of the land surface are spatial and temporal mosaics of both photosynthetic types. We developed an approach for capturing this heterogeneity by combining remote sensing products, physiological modeling, a spatial distribution of global crop fractions, and national harvest area data for major crop types. Our C 3 /C 4 distribution predicts the global coverage of C 4 vegetation to be 18.8 million km 2, while C 3 vegetation covers 87.4 million km 2. We incorporated our distribution into the SiB2 model and simulated carbon fluxes for each photosynthetic type. The gross primary production (GPP) of C 4 plants is 35.3 Pg C yr −1, or ∼23\% of total GPP, while that of C 3 plants is 114.7 Pg C yr −1. The assimilation‐weighted terrestrial discrimination against 13 CO 2 is −16.5‰. If the terrestrial component of the carbon sink is proportional to GPP, this implies a net uptake of 2.4 Pg C yr −1 on land and 1.4 Pg C yr −1 in the ocean using a 13 C budgeting approach and average carbon cycle parameter values for the 1990s. We also simulated the biomass of each photosynthetic type using the CASA model. The simulated biomass values of C 3 and C 4 vegetation are 389.3 and 18.6 Pg C, respectively.",
    url = "https://doi.org/10.1029/2001gb001807",
    doi = "10.1029/2001gb001807",
    openalex = "W1888540468",
    references = "doi1010160302459880800547"
}

Abstract A simple method of estimating changes in biologically active soil carbon (C) could help evaluate soil quality impacts of alternative management practices. Most reports of permanganate for active C determination use highly concentrated solutions (0.333 M) that are difficult to work with and tend to react with a large fraction of soil C that is not well distinguished from total organic C. We report on a highly simplified method in which dilute, slightly alkaline KMnO 4 reacts with the most readily oxidizable (active) forms of soil C, converting Mn(VII) to Mn(II), and proportionally lowering absorbance of 550 nm light. The amount of soil C that reacted increased with concentration of KMnO4 used (0.01 to 0.1 M), degree of soil drying (moist fresh soil to air-dried for 24 hour) and time of shaking (1–15 minutes). Shaking of air-diy soil in a 0.02 M KMnO 4 solution for 2 minutes produced consistent and management-sensitive results, both in the laboratory and with a field kit that used a hand-held colorimeter. Addition of 0.1 M. CaCl 2 to the permanganate reagent enhanced settling of the soil after shaking, eliminating the need for centrifugaron in the field kit. Results from the laboratory and field-kit protocols were nearly identical (R 2 = 0.98), as were those from an inter-laboratory sample exchange (R 2 = 0.91). The active soil C measured by the new procedure was more sensitive to management effects than total organic C, and more closely related to biologically mediated soil properties, such as respiration, microbial biomass and aggregation, than several other measures of soil organic C.

@article{doi101079ajaa200228,
    author = "Weil, Ray R. and Islam, Kandikar R. and Stine, Melissa A. and Gruver, Joel and Samson‐Liebig, S.",
    title = "Estimating active carbon for soil quality assessment: A simplified method for laboratory and field use",
    year = "2003",
    journal = "American Journal of Alternative Agriculture",
    abstract = "Abstract A simple method of estimating changes in biologically active soil carbon (C) could help evaluate soil quality impacts of alternative management practices. Most reports of permanganate for active C determination use highly concentrated solutions (0.333 M) that are difficult to work with and tend to react with a large fraction of soil C that is not well distinguished from total organic C. We report on a highly simplified method in which dilute, slightly alkaline KMnO 4 reacts with the most readily oxidizable (active) forms of soil C, converting Mn(VII) to Mn(II), and proportionally lowering absorbance of 550 nm light. The amount of soil C that reacted increased with concentration of KMnO4 used (0.01 to 0.1 M), degree of soil drying (moist fresh soil to air-dried for 24 hour) and time of shaking (1–15 minutes). Shaking of air-diy soil in a 0.02 M KMnO 4 solution for 2 minutes produced consistent and management-sensitive results, both in the laboratory and with a field kit that used a hand-held colorimeter. Addition of 0.1 M. CaCl 2 to the permanganate reagent enhanced settling of the soil after shaking, eliminating the need for centrifugaron in the field kit. Results from the laboratory and field-kit protocols were nearly identical (R 2 = 0.98), as were those from an inter-laboratory sample exchange (R 2 = 0.91). The active soil C measured by the new procedure was more sensitive to management effects than total organic C, and more closely related to biologically mediated soil properties, such as respiration, microbial biomass and aggregation, than several other measures of soil organic C.",
    url = "https://doi.org/10.1079/ajaa200228",
    doi = "10.1079/ajaa200228",
    openalex = "W2131190889",
    references = "doi1010970001069419470400000001"
}

A new calibration curve for the conversion of radiocarbon ages to calibrated (cal) ages has been constructed and internationally ratified to replace IntCal98, which extended from 0–24 cal kyr BP (Before Present, 0 cal BP = AD 1950). The new calibration data set for terrestrial samples extends from 0–26 cal kyr BP, but with much higher resolution beyond 11.4 cal kyr BP than IntCal98. Dendrochronologically-dated tree-ring samples cover the period from 0–12.4 cal kyr BP. Beyond the end of the tree rings, data from marine records (corals and foraminifera) are converted to the atmospheric equivalent with a site-specific marine reservoir correction to provide terrestrial calibration from 12.4–26.0 cal kyr B P. A substantial enhancement relative to IntCal98 is the introduction of a coherent statistical approach based on a random walk model, which takes into account the uncertainty in both the calendar age and the 14 C age to calculate the underlying calibration curve (Buck and Blackwell, this issue). The tree-ring data sets, sources of uncertainty, and regional offsets are discussed here. The marine data sets and calibration curve for marine samples from the surface mixed layer (Marine04) are discussed in brief, but details are presented in Hughen et al. (this issue a). We do not make a recommendation for calibration beyond 26 cal kyr BP at this time; however, potential calibration data sets are compared in another paper (van der Plicht et al., this issue).

@article{doi101017s0033822200032999,
    author = "Reimer, Paula and Baillie, Mgl and Bard, Édouard and Bayliss, Alex and Beck, J. and Bertrand, Chanda and Blackwell, Pg and Buck, Caitlin E. and Burr, George S. and Cutler, Kb and Damon, P.E. and Edwards, RL and Fairbanks, Rg and Friedrich, Michael and Guilderson, T. P. and Hog, Ag and Hughen, Ka and Kromer, Bernd and McCormac, Gerry and Manning, Sturt W. and Ramsey, Christopher Bronk and Reimer, Rw and Remmele, Sabine and Southon, Jr and Stuiver, M. and Talamo, Sahra and Taylor, Fw and van der Plicht, J. and Weyhenmeyer, C. E.",
    title = "Intcal04 Terrestrial Radiocarbon Age Calibration, 0–26 Cal Kyr BP",
    year = "2004",
    journal = "Radiocarbon",
    abstract = "A new calibration curve for the conversion of radiocarbon ages to calibrated (cal) ages has been constructed and internationally ratified to replace IntCal98, which extended from 0–24 cal kyr BP (Before Present, 0 cal BP = AD 1950). The new calibration data set for terrestrial samples extends from 0–26 cal kyr BP, but with much higher resolution beyond 11.4 cal kyr BP than IntCal98. Dendrochronologically-dated tree-ring samples cover the period from 0–12.4 cal kyr BP. Beyond the end of the tree rings, data from marine records (corals and foraminifera) are converted to the atmospheric equivalent with a site-specific marine reservoir correction to provide terrestrial calibration from 12.4–26.0 cal kyr B P. A substantial enhancement relative to IntCal98 is the introduction of a coherent statistical approach based on a random walk model, which takes into account the uncertainty in both the calendar age and the 14 C age to calculate the underlying calibration curve (Buck and Blackwell, this issue). The tree-ring data sets, sources of uncertainty, and regional offsets are discussed here. The marine data sets and calibration curve for marine samples from the surface mixed layer (Marine04) are discussed in brief, but details are presented in Hughen et al. (this issue a). We do not make a recommendation for calibration beyond 26 cal kyr BP at this time; however, potential calibration data sets are compared in another paper (van der Plicht et al., this issue).",
    url = "https://doi.org/10.1017/s0033822200032999",
    doi = "10.1017/s0033822200032999",
    openalex = "W2154276443",
    references = "doi101017s0033822200013874, doi101017s0033822200019123, doi101017s0033822200019172, doi101017s0033822200033002, doi101017s003382220003304x, doi101017s0033822200060264, doi1010291999pa000464, doi101126science1056649, doi101126science1090300, doi101126science29054981951"
}

New radiocarbon calibration curves, IntCal04 and Marine04, have been constructed and internationally ratified to replace the terrestrial and marine components of IntCal98. The new calibration data sets extend an additional 2000 yr, from 0–26 cal kyr BP (Before Present, 0 cal BP = AD 1950), and provide much higher resolution, greater precision, and more detailed structure than IntCal98. For the Marine04 curve, dendrochronologically-dated tree-ring samples, converted with a box diffusion model to marine mixed-layer ages, cover the period from 0–10.5 cal kyr BP. Beyond 10.5 cal kyr BP, high-resolution marine data become available from foraminifera in varved sediments and U/Th-dated corals. The marine records are corrected with site-specific 14 C reservoir age information to provide a single global marine mixed-layer calibration from 10.5–26.0 cal kyr BP. A substantial enhancement relative to IntCal98 is the introduction of a random walk model, which takes into account the uncertainty in both the calendar age and the 14 C age to calculate the underlying calibration curve (Buck and Blackwell, this issue). The marine data sets and calibration curve for marine samples from the surface mixed layer (Marine04) are discussed here. The tree-ring data sets, sources of uncertainty, and regional offsets are presented in detail in a companion paper by Reimer et al. (this issue).

@article{doi101017s0033822200033002,
    author = "Hughen, Konrad A and Baillie, Mike and Bard, Édouard and Beck, J Warren and Bertrand, Chanda and Blackwell, Paul G. and Buck, Caitlin E. and Burr, George S. and Cutler, Kirsten and Damon, Paul E. and Edwards, R. Lawrence and Fairbanks, Richard G. and Friedrich, Michael and Guilderson, T. P. and Kromer, Bernd and McCormac, Gerry and Manning, Sturt W. and Ramsey, Christopher Bronk and Reimer, Paula and Reimer, Ron and Remmele, Sabine and Southon, John and Stuiver, Minze and Talamo, Sahra and Taylor, Frederick W. and van der Plicht, J. and Weyhenmeyer, Constanze E.",
    title = "Marine04 Marine Radiocarbon Age Calibration, 0–26 Cal Kyr Bp",
    year = "2004",
    journal = "Radiocarbon",
    abstract = "New radiocarbon calibration curves, IntCal04 and Marine04, have been constructed and internationally ratified to replace the terrestrial and marine components of IntCal98. The new calibration data sets extend an additional 2000 yr, from 0–26 cal kyr BP (Before Present, 0 cal BP = AD 1950), and provide much higher resolution, greater precision, and more detailed structure than IntCal98. For the Marine04 curve, dendrochronologically-dated tree-ring samples, converted with a box diffusion model to marine mixed-layer ages, cover the period from 0–10.5 cal kyr BP. Beyond 10.5 cal kyr BP, high-resolution marine data become available from foraminifera in varved sediments and U/Th-dated corals. The marine records are corrected with site-specific 14 C reservoir age information to provide a single global marine mixed-layer calibration from 10.5–26.0 cal kyr BP. A substantial enhancement relative to IntCal98 is the introduction of a random walk model, which takes into account the uncertainty in both the calendar age and the 14 C age to calculate the underlying calibration curve (Buck and Blackwell, this issue). The marine data sets and calibration curve for marine samples from the surface mixed layer (Marine04) are discussed here. The tree-ring data sets, sources of uncertainty, and regional offsets are presented in detail in a companion paper by Reimer et al. (this issue).",
    url = "https://doi.org/10.1017/s0033822200033002",
    doi = "10.1017/s0033822200033002",
    openalex = "W1909880476",
    references = "doi101016s0009254199001576, doi101017s0033822200013874, doi101017s0033822200019123, doi101017s0033822200019172, doi101017s0033822200032999, doi101017s0033822200040121, doi101017s0033822200060264, doi101017s0033822200064778, doi101038315045a0, doi101038346456a0, doi103402tellusav27i29900"
}

The combined oak and pine tree-ring chronologies of Hohenheim University are the backbone of the Holocene radiocarbon calibration for central Europe. Here, we present the revised Holocene oak chronology (HOC) and the Preboreal pine chronology (PPC) with respect to revisions, critical links, and extensions. Since 1998, the HOC has been strengthened by new trees starting at 10,429 BP (8480 BC). Oaks affected by cockchafer have been identified and discarded from the chronology. The formerly floating PPC has been cross-matched dendrochronologically to the absolutely dated oak chronology, which revealed a difference of only 8 yr to the published 14 C wiggle-match position used for IntCal98. The 2 parts of the PPC, which were linked tentatively at 11,250 BP, have been revised and strengthened by new trees, which enabled us to link both parts of the PPC dendrochronologically. Including the 8-yr shift of the oak-pine link, the older part of the PPC (pre-11,250 BP) needs to be shifted 70 yr to older ages with respect to the published data (Spurk 1998). The southern German part of the PPC now covers 2103 yr from 11,993–9891 BP (10,044–7942 BC). In addition, the PPC was extended significantly by new pine chronologies from other regions. A pine chronology from Avenches and Zürich, Switzerland, and another from the Younger Dryas forest of Cottbus, eastern Germany, could be crossdated and dendrochronologically matched to the PPC. The absolutely dated tree-ring chronology now extends back to 12,410 cal BP (10,461 BC). Therefore, the tree-ring-based 14 C calibration now reaches back into the Central Younger Dryas. With respect to the Younger Dryas-Preboreal transition identified in the ring width of our pines at 11,590 BP, the absolute tree-ring chronology now covers the entire Holocene and 820 yr of the Younger Dryas.

@article{doi101017s003382220003304x,
    author = "Friedrich, Michael and Remmele, Sabine and Kromer, Bernd and Hofmann, Jutta and Spurk, Marco and Kaiser, Klaus Félix and Orcel, Christian and Küppers, Manfred",
    title = "The 12,460-Year Hohenheim Oak and Pine Tree-Ring Chronology from Central Europe—A Unique Annual Record for Radiocarbon Calibration and Paleoenvironment Reconstructions",
    year = "2004",
    journal = "Radiocarbon",
    abstract = "The combined oak and pine tree-ring chronologies of Hohenheim University are the backbone of the Holocene radiocarbon calibration for central Europe. Here, we present the revised Holocene oak chronology (HOC) and the Preboreal pine chronology (PPC) with respect to revisions, critical links, and extensions. Since 1998, the HOC has been strengthened by new trees starting at 10,429 BP (8480 BC). Oaks affected by cockchafer have been identified and discarded from the chronology. The formerly floating PPC has been cross-matched dendrochronologically to the absolutely dated oak chronology, which revealed a difference of only 8 yr to the published 14 C wiggle-match position used for IntCal98. The 2 parts of the PPC, which were linked tentatively at 11,250 BP, have been revised and strengthened by new trees, which enabled us to link both parts of the PPC dendrochronologically. Including the 8-yr shift of the oak-pine link, the older part of the PPC (pre-11,250 BP) needs to be shifted 70 yr to older ages with respect to the published data (Spurk 1998). The southern German part of the PPC now covers 2103 yr from 11,993–9891 BP (10,044–7942 BC). In addition, the PPC was extended significantly by new pine chronologies from other regions. A pine chronology from Avenches and Zürich, Switzerland, and another from the Younger Dryas forest of Cottbus, eastern Germany, could be crossdated and dendrochronologically matched to the PPC. The absolutely dated tree-ring chronology now extends back to 12,410 cal BP (10,461 BC). Therefore, the tree-ring-based 14 C calibration now reaches back into the Central Younger Dryas. With respect to the Younger Dryas-Preboreal transition identified in the ring width of our pines at 11,590 BP, the absolute tree-ring chronology now covers the entire Holocene and 820 yr of the Younger Dryas.",
    url = "https://doi.org/10.1017/s003382220003304x",
    doi = "10.1017/s003382220003304x",
    openalex = "W1942153202"
}

Comprehensive published radiocarbon data from selected atmospheric records, tree rings, and recent organic matter were analyzed and grouped into 4 different zones (three for the Northern Hemisphere and one for the whole Southern Hemisphere). These 14 C data for the summer season of each hemisphere were employed to construct zonal, hemispheric, and global data sets for use in regional and global carbon model calculations including calibrating and comparing carbon cycle models. In addition, extended monthly atmospheric 14 C data sets for 4 different zones were compiled for age calibration purposes. This is the first time these data sets were constructed to facilitate the dating of recent organic material using the bomb 14 C curves. The distribution of bomb 14 C reflects the major zones of atmospheric circulation.

@article{doi101017s0033822200033142,
    author = "Hua, Quan and Barbetti, Mike",
    title = "Review of Tropospheric Bomb 14 C Data for Carbon Cycle Modeling and Age Calibration Purposes",
    year = "2004",
    journal = "Radiocarbon",
    abstract = "Comprehensive published radiocarbon data from selected atmospheric records, tree rings, and recent organic matter were analyzed and grouped into 4 different zones (three for the Northern Hemisphere and one for the whole Southern Hemisphere). These 14 C data for the summer season of each hemisphere were employed to construct zonal, hemispheric, and global data sets for use in regional and global carbon model calculations including calibrating and comparing carbon cycle models. In addition, extended monthly atmospheric 14 C data sets for 4 different zones were compiled for age calibration purposes. This is the first time these data sets were constructed to facilitate the dating of recent organic material using the bomb 14 C curves. The distribution of bomb 14 C reflects the major zones of atmospheric circulation.",
    url = "https://doi.org/10.1017/s0033822200033142",
    doi = "10.1017/s0033822200033142",
    openalex = "W1494081909",
    references = "doi101017s0033822200003672, doi101017s0033822200032999, doi101017s0033822200033154, doi101017s0033822200053066, doi101029jc088ic06p03621, doi101029jz065i009p02903, doi10106314823194, doi101111j215334901975tb01671x, doi103402tellusav27i29900, openalexw1928750549"
}

The eruption of the volcano at Thera (Santorini) in the Aegean Sea undoubtedly had a profound influence on the civilizations of the surrounding region. The date of the eruption has been a subject of much controversy because it must be linked into the established and intricate archaeological phasings of both the prehistoric Aegean and the wider east Mediterranean. Radiocarbon dating of material from the volcanic destruction layer itself can provide some evidence for the date of the eruption, but because of the shape of the calibration curve for the relevant period, the value of such dates relies on there being no biases in the data sets. However, by dating the material from phases earlier and later than the eruption, some of the problems of the calibration data set can be circumvented and the chronology for the region can be resolved with more certainty. In this paper, we draw together the evidence we have accumulated so far, including new data on the destruction layer itself and for the preceding cultural horizon at Thera, and from associated layers at Miletos in western Turkey. Using Bayesian models to synthesize the data and to identify outliers, we conclude from the most reliable 14 C evidence (and using the INTCAL98 calibration data set) that the eruption of Thera occurred between 1663 and 1599 BC.

@article{doi101017s0033822200039631,
    author = "Ramsey, Christopher Bronk and Manning, Sturt W. and Galimberti, Mariagrazia",
    title = "Dating the Volcanic Eruption at Thera",
    year = "2004",
    journal = "Radiocarbon",
    abstract = "The eruption of the volcano at Thera (Santorini) in the Aegean Sea undoubtedly had a profound influence on the civilizations of the surrounding region. The date of the eruption has been a subject of much controversy because it must be linked into the established and intricate archaeological phasings of both the prehistoric Aegean and the wider east Mediterranean. Radiocarbon dating of material from the volcanic destruction layer itself can provide some evidence for the date of the eruption, but because of the shape of the calibration curve for the relevant period, the value of such dates relies on there being no biases in the data sets. However, by dating the material from phases earlier and later than the eruption, some of the problems of the calibration data set can be circumvented and the chronology for the region can be resolved with more certainty. In this paper, we draw together the evidence we have accumulated so far, including new data on the destruction layer itself and for the preceding cultural horizon at Thera, and from associated layers at Miletos in western Turkey. Using Bayesian models to synthesize the data and to identify outliers, we conclude from the most reliable 14 C evidence (and using the INTCAL98 calibration data set) that the eruption of Thera occurred between 1663 and 1599 BC.",
    url = "https://doi.org/10.1017/s0033822200039631",
    doi = "10.1017/s0033822200039631",
    openalex = "W1770490023"
}

During the 1990s, ocean sampling expeditions were carried out as part of the World Ocean Circulation Experiment (WOCE), the Joint Global Ocean Flux Study (JGOFS), and the Ocean Atmosphere Carbon Exchange Study (OACES). Subsequently, a group of U.S. scientists synthesized the data into easily usable and readily available products. This collaboration is known as the Global Ocean Data Analysis Project (GLODAP). Results were merged into a common format data set, segregated by ocean. For comparison purposes, each ocean data set includes a small number of high‐quality historical cruises. The data were subjected to rigorous quality control procedures to eliminate systematic data measurement biases. The calibrated 1990s data were used to estimate anthropogenic CO 2, potential alkalinity, CFC watermass ages, CFC partial pressure, bomb‐produced radiocarbon, and natural radiocarbon. These quantities were merged into the measured data files. The data were used to produce objectively gridded property maps at a 1° resolution on 33 depth surfaces chosen to match existing climatologies for temperature, salinity, oxygen, and nutrients. The mapped fields are interpreted as an annual mean distribution in spite of the inaccuracy in that assumption. Both the calibrated data and the gridded products are available from the Carbon Dioxide Information Analysis Center. Here we describe the important details of the data treatment and the mapping procedure, and present summary quantities and integrals for the various parameters.

@article{doi1010292004gb002247,
    author = "Key, Robert M. and Kozyr, Alex and Sabine, C. and Lee, Kitack and Wanninkhof, Rik and Bullister, John L. and Feely, Richard A. and Millero, Frank J. and Mordy, Calvin W. and Peng, Tianji",
    title = "A global ocean carbon climatology: Results from Global Data Analysis Project (GLODAP)",
    year = "2004",
    journal = "Global Biogeochemical Cycles",
    abstract = "During the 1990s, ocean sampling expeditions were carried out as part of the World Ocean Circulation Experiment (WOCE), the Joint Global Ocean Flux Study (JGOFS), and the Ocean Atmosphere Carbon Exchange Study (OACES). Subsequently, a group of U.S. scientists synthesized the data into easily usable and readily available products. This collaboration is known as the Global Ocean Data Analysis Project (GLODAP). Results were merged into a common format data set, segregated by ocean. For comparison purposes, each ocean data set includes a small number of high‐quality historical cruises. The data were subjected to rigorous quality control procedures to eliminate systematic data measurement biases. The calibrated 1990s data were used to estimate anthropogenic CO 2, potential alkalinity, CFC watermass ages, CFC partial pressure, bomb‐produced radiocarbon, and natural radiocarbon. These quantities were merged into the measured data files. The data were used to produce objectively gridded property maps at a 1° resolution on 33 depth surfaces chosen to match existing climatologies for temperature, salinity, oxygen, and nutrients. The mapped fields are interpreted as an annual mean distribution in spite of the inaccuracy in that assumption. Both the calibrated data and the gridded products are available from the Carbon Dioxide Information Analysis Center. Here we describe the important details of the data treatment and the mapping procedure, and present summary quantities and integrals for the various parameters.",
    url = "https://doi.org/10.1029/2004gb002247",
    doi = "10.1029/2004gb002247",
    openalex = "W1609491364",
    references = "doi1010160198014987900215, doi10102990eo00319, doi10102996jb00104, doi10102998eo00426, doi101126science1097329, doi101126science1097403, doi104319lo19731860897, openalexw3041301201, openalexw344835664"
}

A series of 14C measurements in Ocean Drilling Program cores from the tropical Cariaco Basin, which have been correlated to the annual-layer counted chronology for the Greenland Ice Sheet Project 2 (GISP2) ice core, provides a high-resolution calibration of the radiocarbon time scale back to 50,000 years before the present. Independent radiometric dating of events correlated to GISP2 suggests that the calibration is accurate. Reconstructed 14C activities varied substantially during the last glacial period, including sharp peaks synchronous with the Laschamp and Mono Lake geomagnetic field intensity minimal and cosmogenic nuclide peaks in ice cores and marine sediments. Simulations with a geochemical box model suggest that much of the variability can be explained by geomagnetically modulated changes in 14C production rate together with plausible changes in deep-ocean ventilation and the global carbon cycle during glaciation.

@article{doi101126science1090300,
    author = "Hughen, Konrad A and Lehman, Scott J. and Southon, John and Overpeck, Jonathan T. and Marchal, Olivier and Herring, C. and Turnbull, Jocelyn",
    title = "14 C Activity and Global Carbon Cycle Changes over the Past 50,000 Years",
    year = "2004",
    journal = "Science",
    abstract = "A series of 14C measurements in Ocean Drilling Program cores from the tropical Cariaco Basin, which have been correlated to the annual-layer counted chronology for the Greenland Ice Sheet Project 2 (GISP2) ice core, provides a high-resolution calibration of the radiocarbon time scale back to 50,000 years before the present. Independent radiometric dating of events correlated to GISP2 suggests that the calibration is accurate. Reconstructed 14C activities varied substantially during the last glacial period, including sharp peaks synchronous with the Laschamp and Mono Lake geomagnetic field intensity minimal and cosmogenic nuclide peaks in ice cores and marine sediments. Simulations with a geochemical box model suggest that much of the variability can be explained by geomagnetically modulated changes in 14C production rate together with plausible changes in deep-ocean ventilation and the global carbon cycle during glaciation.",
    url = "https://doi.org/10.1126/science.1090300",
    doi = "10.1126/science.1090300",
    openalex = "W2057377643",
    references = "doi101038nature01391, doi101126science27953541187"
}

The relation between the partial pressure of atmospheric carbon dioxide (pCO2) and Paleogene climate is poorly resolved. We used stable carbon isotopic values of di-unsaturated alkenones extracted from deep sea cores to reconstruct pCO2 from the middle Eocene to the late Oligocene (approximately 45 to 25 million years ago). Our results demonstrate that pCO2 ranged between 1000 to 1500 parts per million by volume in the middle to late Eocene, then decreased in several steps during the Oligocene, and reached modern levels by the latest Oligocene. The fall in pCO2 likely allowed for a critical expansion of ice sheets on Antarctica and promoted conditions that forced the onset of terrestrial C4 photosynthesis.

@article{doi101126science1110063,
    author = "Pagani, Mark and Zachos, James C. and Freeman, Katherine H. and Tipple, Brett J. and Bohaty, S. M.",
    title = "Marked Decline in Atmospheric Carbon Dioxide Concentrations During the Paleogene",
    year = "2005",
    journal = "Science",
    abstract = "The relation between the partial pressure of atmospheric carbon dioxide (pCO2) and Paleogene climate is poorly resolved. We used stable carbon isotopic values of di-unsaturated alkenones extracted from deep sea cores to reconstruct pCO2 from the middle Eocene to the late Oligocene (approximately 45 to 25 million years ago). Our results demonstrate that pCO2 ranged between 1000 to 1500 parts per million by volume in the middle to late Eocene, then decreased in several steps during the Oligocene, and reached modern levels by the latest Oligocene. The fall in pCO2 likely allowed for a critical expansion of ice sheets on Antarctica and promoted conditions that forced the onset of terrestrial C4 photosynthesis.",
    url = "https://doi.org/10.1126/science.1110063",
    doi = "10.1126/science.1110063",
    openalex = "W1999809323",
    references = "doi1010160012821x74900788, doi1010160016703792901426, doi101016003101828690009x, doi1010160377839889900340, doi10102993pa03266, doi10102996pa00571, doi101038nature03135, doi101111j14698137200400974x, doi102110pec9504, doi102475ajs3012182"
}

Desert dust simulations generated by the National Center for Atmospheric Research's Community Climate System Model for the current climate are shown to be consistent with present day satellite and deposition data. The response of the dust cycle to last glacial maximum, preindustrial, modern, and doubled‐carbon dioxide climates is analyzed. Only natural (non‐land use related) dust sources are included in this simulation. Similar to some previous studies, dust production mainly responds to changes in the source areas from vegetation changes, not from winds or soil moisture changes alone. This model simulates a +92%, +33%, and −60% change in dust loading for the last glacial maximum, preindustrial, and doubled‐carbon dioxide climate, respectively, when impacts of carbon dioxide fertilization on vegetation are included in the model. Terrestrial sediment records from the last glacial maximum compiled here indicate a large underestimate of deposition in continental regions, probably due to the lack of simulation of glaciogenic dust sources. In order to include the glaciogenic dust sources as a first approximation, we designate the location of these sources, and infer the size of the sources using an inversion method that best matches the available data. The inclusion of these inferred glaciogenic dust sources increases our dust flux in the last glacial maximum from 2.1 to 3.3 times current deposition.

@article{doi1010292005jd006653,
    author = "Mahowald, N. M. and Muhs, Daniel R. and Levis, Samuel and Rasch, Philip J. and Yoshioka, Masaru and Zender, Charles S. and Luo, Chao",
    title = "Change in atmospheric mineral aerosols in response to climate: Last glacial period, preindustrial, modern, and doubled carbon dioxide climates",
    year = "2006",
    journal = "Journal of Geophysical Research Atmospheres",
    abstract = "Desert dust simulations generated by the National Center for Atmospheric Research's Community Climate System Model for the current climate are shown to be consistent with present day satellite and deposition data. The response of the dust cycle to last glacial maximum, preindustrial, modern, and doubled‐carbon dioxide climates is analyzed. Only natural (non‐land use related) dust sources are included in this simulation. Similar to some previous studies, dust production mainly responds to changes in the source areas from vegetation changes, not from winds or soil moisture changes alone. This model simulates a +92\%, +33\%, and −60\% change in dust loading for the last glacial maximum, preindustrial, and doubled‐carbon dioxide climate, respectively, when impacts of carbon dioxide fertilization on vegetation are included in the model. Terrestrial sediment records from the last glacial maximum compiled here indicate a large underestimate of deposition in continental regions, probably due to the lack of simulation of glaciogenic dust sources. In order to include the glaciogenic dust sources as a first approximation, we designate the location of these sources, and infer the size of the sources using an inversion method that best matches the available data. The inclusion of these inferred glaciogenic dust sources increases our dust flux in the last glacial maximum from 2.1 to 3.3 times current deposition.",
    url = "https://doi.org/10.1029/2005jd006653",
    doi = "10.1029/2005jd006653",
    openalex = "W1988110777",
    references = "doi101016jquascirev200409007, doi101016s0012825201000423, doi101016s0277379103001677, doi101016s0277379103001690, doi1010292000jd000053, doi1010292000rg000095, doi1010292002jd002775, doi1010292004gb002402, doi10102995jd00690, doi101029pa005i001p00001, doi10103817276, doi101093oso97801985409220010001, doi101256004316502320517344, doi1023071551023, doi10230720033020"
}

As part of the effort to create the new Greenland Ice Core Chronology 2005 (GICC05) a synchronized stratigraphical timescale for the Holocene parts of the DYE‐3, Greenland Ice Core Project (GRIP), and North Greenland Ice Core Project (NGRIP) ice cores is made by using volcanic reference horizons in electrical conductivity measurements to match the cores. The main annual layer counting is carried out on the most suited records only, exploiting that the three ice cores have been drilled at locations with different climatic conditions and differences in ice flow. However, supplemental counting on data from all cores has been performed between each set of reference horizons in order to verify the validity of the match. After the verification, the main dating is transferred to all records using the volcanic reference horizons as tie points. An assessment of the mean annual layer thickness in each core section confirms that the new synchronized dating is consistent for all three cores. The data used for the main annual layer counting of the past 7900 years are the DYE‐3, GRIP, and NGRIP stable isotope records. As the high accumulation rate at the DYE‐3 drill site makes the seasonal cycle in the DYE‐3 stable isotopes very resistant to firn diffusion, an effort has been made to extend the DYE‐3 Holocene record. The new synchronized dating relies heavily on this record of ∼75,000 stable isotope samples. The dating of the early Holocene consists of an already established part of GICC05 for GRIP and NGRIP which has now been transferred to the DYE‐3 core. GICC05 dates the Younger Dryas termination, as defined from deuterium excess, to 11,703 years before A. D. 2000 (b2k), 130 years earlier than the previous GRIP dating.

@article{doi1010292005jd006921,
    author = "Vinther, Bo and Clausen, Henrik and Johnsen, S. J. and Rasmussen, Sune Olander and Andersen, K. K. and Buchardt, S. L. and Dahl‐Jensen, Dorthe and Seierstad, Inger K and Siggaard‐Andersen, M.‐L. and Steffensen, J. P. and Svensson, Anders and Olsen, Jesper and Heinemeier, Jan",
    title = "A synchronized dating of three Greenland ice cores throughout the Holocene",
    year = "2006",
    journal = "Journal of Geophysical Research Atmospheres",
    abstract = "As part of the effort to create the new Greenland Ice Core Chronology 2005 (GICC05) a synchronized stratigraphical timescale for the Holocene parts of the DYE‐3, Greenland Ice Core Project (GRIP), and North Greenland Ice Core Project (NGRIP) ice cores is made by using volcanic reference horizons in electrical conductivity measurements to match the cores. The main annual layer counting is carried out on the most suited records only, exploiting that the three ice cores have been drilled at locations with different climatic conditions and differences in ice flow. However, supplemental counting on data from all cores has been performed between each set of reference horizons in order to verify the validity of the match. After the verification, the main dating is transferred to all records using the volcanic reference horizons as tie points. An assessment of the mean annual layer thickness in each core section confirms that the new synchronized dating is consistent for all three cores. The data used for the main annual layer counting of the past 7900 years are the DYE‐3, GRIP, and NGRIP stable isotope records. As the high accumulation rate at the DYE‐3 drill site makes the seasonal cycle in the DYE‐3 stable isotopes very resistant to firn diffusion, an effort has been made to extend the DYE‐3 Holocene record. The new synchronized dating relies heavily on this record of ∼75,000 stable isotope samples. The dating of the early Holocene consists of an already established part of GICC05 for GRIP and NGRIP which has now been transferred to the DYE‐3 core. GICC05 dates the Younger Dryas termination, as defined from deuterium excess, to 11,703 years before A. D. 2000 (b2k), 130 years earlier than the previous GRIP dating.",
    url = "https://doi.org/10.1029/2005jd006921",
    doi = "10.1029/2005jd006921",
    openalex = "W2108952763",
    references = "doi101017s0022143000031208"
}

Abstract Net ecosystem production is the residual of two much larger fluxes: photosynthesis and respiration. While photosynthesis is a single process with a well‐established theoretical underpinning, respiration integrates the variety of plant and microbial processes by which CO 2 returns from ecosystems to the atmosphere. Limits to current capacity for predicting ecosystem respiration fluxes across biomes or years result from the mismatch between what is usually measured – bulk CO 2 fluxes – and what process‐based models can predict – fluxes of CO 2 from plant (autotrophic) or microbial (heterotrophic) respiration. Papers in this Thematic Issue and in the recent literature, document advances in methods for separating respiration into autotrophic and heterotrophic components using three approaches: (1) continuous measurements of CO 2 fluxes and assimilation of these data into process‐based models; (2) application of isotope measurements, particularly radiocarbon; and (3) manipulation experiments. They highlight the role of allocation of C fixed by plants to respiration, storage, growth or transfer to other organisms as a control of seasonal and interannual variability in soil respiration and the oxidation state of C in the terrestrial biosphere. A second theme is the potential for comparing C isotope signatures in organic matter, CO 2 evolved in incubations and microbial biomarkers to elucidate the pathways (respiration, recycling, or transformation) of C during decomposition. Together, these factors determine the continuum of timescales over which C is returned to the atmosphere by respiration and enable testing of theories of plant and microbial respiration that go beyond empirical models and allow predictions of future respiration responses to future change in climate, pollution and land use.

@article{doi101111j13652486200601067x,
    author = "Trumbore, Susan",
    title = "Carbon respired by terrestrial ecosystems – recent progress and challenges",
    year = "2006",
    journal = "Global Change Biology",
    abstract = "Abstract Net ecosystem production is the residual of two much larger fluxes: photosynthesis and respiration. While photosynthesis is a single process with a well‐established theoretical underpinning, respiration integrates the variety of plant and microbial processes by which CO 2 returns from ecosystems to the atmosphere. Limits to current capacity for predicting ecosystem respiration fluxes across biomes or years result from the mismatch between what is usually measured – bulk CO 2 fluxes – and what process‐based models can predict – fluxes of CO 2 from plant (autotrophic) or microbial (heterotrophic) respiration. Papers in this Thematic Issue and in the recent literature, document advances in methods for separating respiration into autotrophic and heterotrophic components using three approaches: (1) continuous measurements of CO 2 fluxes and assimilation of these data into process‐based models; (2) application of isotope measurements, particularly radiocarbon; and (3) manipulation experiments. They highlight the role of allocation of C fixed by plants to respiration, storage, growth or transfer to other organisms as a control of seasonal and interannual variability in soil respiration and the oxidation state of C in the terrestrial biosphere. A second theme is the potential for comparing C isotope signatures in organic matter, CO 2 evolved in incubations and microbial biomarkers to elucidate the pathways (respiration, recycling, or transformation) of C during decomposition. Together, these factors determine the continuum of timescales over which C is returned to the atmosphere by respiration and enable testing of theories of plant and microbial respiration that go beyond empirical models and allow predictions of future respiration responses to future change in climate, pollution and land use.",
    url = "https://doi.org/10.1111/j.1365-2486.2006.01067.x",
    doi = "10.1111/j.1365-2486.2006.01067.x",
    openalex = "W2158806627",
    references = "doi101017s0033822200053066"
}

Precise and direct dating of the Minoan eruption of Santorini (Thera) in Greece, a global Bronze Age time marker, has been made possible by the unique find of an olive tree, buried alive in life position by the tephra (pumice and ashes) on Santorini. We applied so-called radiocarbon wiggle-matching to a carbon-14 sequence of tree-ring segments to constrain the eruption date to the range 1627-1600 B.C. with 95.4% probability. Our result is in the range of previous, less precise, and less direct results of several scientific dating methods, but it is a century earlier than the date derived from traditional Egyptian chronologies.

@article{doi101126science1125087,
    author = "Friedrich, Walter and Kromer, Bernd and Friedrich, Michael and Heinemeier, Jan and Pfeiffer, Tom and Talamo, Sahra",
    title = "Santorini Eruption Radiocarbon Dated to 1627-1600 B.C.",
    year = "2006",
    journal = "Science",
    abstract = "Precise and direct dating of the Minoan eruption of Santorini (Thera) in Greece, a global Bronze Age time marker, has been made possible by the unique find of an olive tree, buried alive in life position by the tephra (pumice and ashes) on Santorini. We applied so-called radiocarbon wiggle-matching to a carbon-14 sequence of tree-ring segments to constrain the eruption date to the range 1627-1600 B.C. with 95.4\% probability. Our result is in the range of previous, less precise, and less direct results of several scientific dating methods, but it is a century earlier than the date derived from traditional Egyptian chronologies.",
    url = "https://doi.org/10.1126/science.1125087",
    doi = "10.1126/science.1125087",
    openalex = "W2073478171",
    references = "doi101017s0033822200038248, doi101017s0033822200039631"
}

@incollection{crossref2007carbon,
    title = "Carbon 14",
    year = "2007",
    booktitle = "Encyclopedic Dictionary of Polymers",
    url = "https://doi.org/10.1007/978-0-387-30160-0\_1894",
    doi = "10.1007/978-0-387-30160-0\_1894",
    pages = "158-158"
}

@misc{crossref2007carbon14,
    title = "Carbon‐14",
    year = "2007",
    booktitle = "Hawley's Condensed Chemical Dictionary",
    url = "https://doi.org/10.1002/9780470114735.hawley02944",
    doi = "10.1002/9780470114735.hawley02944",
    pages = "232-232"
}

The 14 CO 2 released into the stratosphere during bomb testing in the early 1960s provides a global constraint on air‐sea gas exchange of soluble atmospheric gases like CO 2. Using the most complete database of dissolved inorganic radiocarbon, DI 14 C, available to date and a suite of ocean general circulation models in an inverse mode we recalculate the ocean inventory of bomb‐produced DI 14 C in the global ocean and confirm that there is a 25% decrease from previous estimates using older DI 14 C data sets. Additionally, we find a 33% lower globally averaged gas transfer velocity for CO 2 compared to previous estimates (Wanninkhof, 1992) using the NCEP/NCAR Reanalysis 1 1954–2000 where the global mean winds are 6.9 m s −1. Unlike some earlier ocean radiocarbon studies, the implied gas transfer velocity finally closes the gap between small‐scale deliberate tracer studies and global‐scale estimates. Additionally, the total inventory of bomb‐produced radiocarbon in the ocean is now in agreement with global budgets based on radiocarbon measurements made in the stratosphere and troposphere. Using the implied relationship between wind speed and gas transfer velocity k s = 0.27〈 u 10 2 〉(Sc /660) −0.5 and standard partial pressure difference climatology of CO 2 we obtain an net air‐sea flux estimate of 1.3 ± 0.5 PgCyr −1 for 1995. After accounting for the carbon transferred from rivers to the deep ocean, our estimate of oceanic uptake (1.8 ± 0.5 PgCyr −1) compares well with estimates based on ocean inventories, ocean transport inversions using ocean concentration data, and model simulations.

@article{doi1010292006gb002784,
    author = "Sweeney, Colm and Gloor, Emanuel and Jacobson, A. R. and Key, Robert M. and McKinley, Galen A. and Sarmiento, Jorge L. and Wanninkhof, Rik",
    title = "Constraining global air‐sea gas exchange for CO 2 with recent bomb 14 C measurements",
    year = "2007",
    journal = "Global Biogeochemical Cycles",
    abstract = "The 14 CO 2 released into the stratosphere during bomb testing in the early 1960s provides a global constraint on air‐sea gas exchange of soluble atmospheric gases like CO 2. Using the most complete database of dissolved inorganic radiocarbon, DI 14 C, available to date and a suite of ocean general circulation models in an inverse mode we recalculate the ocean inventory of bomb‐produced DI 14 C in the global ocean and confirm that there is a 25\% decrease from previous estimates using older DI 14 C data sets. Additionally, we find a 33\% lower globally averaged gas transfer velocity for CO 2 compared to previous estimates (Wanninkhof, 1992) using the NCEP/NCAR Reanalysis 1 1954–2000 where the global mean winds are 6.9 m s −1. Unlike some earlier ocean radiocarbon studies, the implied gas transfer velocity finally closes the gap between small‐scale deliberate tracer studies and global‐scale estimates. Additionally, the total inventory of bomb‐produced radiocarbon in the ocean is now in agreement with global budgets based on radiocarbon measurements made in the stratosphere and troposphere. Using the implied relationship between wind speed and gas transfer velocity k s = 0.27〈 u 10 2 〉(Sc /660) −0.5 and standard partial pressure difference climatology of CO 2 we obtain an net air‐sea flux estimate of 1.3 ± 0.5 PgCyr −1 for 1995. After accounting for the carbon transferred from rivers to the deep ocean, our estimate of oceanic uptake (1.8 ± 0.5 PgCyr −1) compares well with estimates based on ocean inventories, ocean transport inversions using ocean concentration data, and model simulations.",
    url = "https://doi.org/10.1029/2006gb002784",
    doi = "10.1029/2006gb002784",
    openalex = "W1678157725",
    references = "doi10100797894009473825, doi101016001670379591550d, doi101016s0967064502000036, doi1010292004gb002247, doi10102992jc00188, doi101126science1097403, doi101126science24749491431, doi10113719781611971217, doi1011751520047719960770437tnyrp20co2, openalexw2774899977"
}

Plants must achieve a balance between carbon assimilation, storage and growth, but little is known about how this is achieved. We describe evidence for the existence of regulatory mechanisms that coordinate carbon supply and use, and the likely central role of sugar signalling. We propose the existence of both 'acute' and 'acclimatory' responses to alterations in carbon supply, the latter tuning the balance between carbon supply and demand to optimise the capacity for sustained growth. A full understanding of these responses requires new, systems-level approaches that integrate information from transcriptomic, enzyme activity, metabolomic and growth analyses. We illustrate the complexity of acute and acclimatory responses by consideration of the control of starch synthesis and degradation in leaves. Finally, we consider how carbon balance may be linked to growth, and the importance of these linkages for sustained plant growth in a changing environment.

@article{doi101111j13653040200701708x,
    author = "Smith, Alison M. and Stitt, Mark",
    title = "Coordination of carbon supply and plant growth",
    year = "2007",
    journal = "Plant Cell \& Environment",
    abstract = "Plants must achieve a balance between carbon assimilation, storage and growth, but little is known about how this is achieved. We describe evidence for the existence of regulatory mechanisms that coordinate carbon supply and use, and the likely central role of sugar signalling. We propose the existence of both 'acute' and 'acclimatory' responses to alterations in carbon supply, the latter tuning the balance between carbon supply and demand to optimise the capacity for sustained growth. A full understanding of these responses requires new, systems-level approaches that integrate information from transcriptomic, enzyme activity, metabolomic and growth analyses. We illustrate the complexity of acute and acclimatory responses by consideration of the control of starch synthesis and degradation in leaves. Finally, we consider how carbon balance may be linked to growth, and the importance of these linkages for sustained plant growth in a changing environment.",
    url = "https://doi.org/10.1111/j.1365-3040.2007.01708.x",
    doi = "10.1111/j.1365-3040.2007.01708.x",
    openalex = "W2101778601"
}

Net primary production (NPP) is commonly modeled as a function of chlorophyll concentration (Chl), even though it has been long recognized that variability in intracellular chlorophyll content from light acclimation and nutrient stress confounds the relationship between Chl and phytoplankton biomass. It was suggested previously that satellite estimates of backscattering can be related to phytoplankton carbon biomass (C) under conditions of a conserved particle size distribution or a relatively stable relationship between C and total particulate organic carbon. Together, C and Chl can be used to describe physiological state (through variations in Chl:C ratios) and NPP. Here, we fully develop the carbon‐based productivity model (CbPM) to include information on the subsurface light field and nitracline depths to parameterize photoacclimation and nutrient stress throughout the water column. This depth‐resolved approach produces profiles of biological properties (Chl, C, NPP) that are broadly consistent with observations. The CbPM is validated using regional in situ data sets of irradiance‐derived products, phytoplankton chlorophyll:carbon ratios, and measured NPP rates. CbPM‐based distributions of global NPP are significantly different in both space and time from previous Chl‐based estimates because of the distinction between biomass and physiological influences on global Chl fields. The new model yields annual, areally integrated water column production of ∼52 Pg C a −1 for the global oceans.

@article{doi1010292007gb003078,
    author = "Westberry, Toby K. and Behrenfeld, Michael J. and Siegel, David A. and Boss, Emmanuel",
    title = "Carbon‐based primary productivity modeling with vertically resolved photoacclimation",
    year = "2008",
    journal = "Global Biogeochemical Cycles",
    abstract = "Net primary production (NPP) is commonly modeled as a function of chlorophyll concentration (Chl), even though it has been long recognized that variability in intracellular chlorophyll content from light acclimation and nutrient stress confounds the relationship between Chl and phytoplankton biomass. It was suggested previously that satellite estimates of backscattering can be related to phytoplankton carbon biomass (C) under conditions of a conserved particle size distribution or a relatively stable relationship between C and total particulate organic carbon. Together, C and Chl can be used to describe physiological state (through variations in Chl:C ratios) and NPP. Here, we fully develop the carbon‐based productivity model (CbPM) to include information on the subsurface light field and nitracline depths to parameterize photoacclimation and nutrient stress throughout the water column. This depth‐resolved approach produces profiles of biological properties (Chl, C, NPP) that are broadly consistent with observations. The CbPM is validated using regional in situ data sets of irradiance‐derived products, phytoplankton chlorophyll:carbon ratios, and measured NPP rates. CbPM‐based distributions of global NPP are significantly different in both space and time from previous Chl‐based estimates because of the distinction between biomass and physiological influences on global Chl fields. The new model yields annual, areally integrated water column production of ∼52 Pg C a −1 for the global oceans.",
    url = "https://doi.org/10.1029/2007gb003078",
    doi = "10.1029/2007gb003078",
    openalex = "W2121131753"
}

Loess deposits preserve important records of Quaternary climate change and atmospheric dust flux; however, their full significance can only be revealed once a reliable chronology is established. Our understanding of loess‐palaeosol sequences and the development of luminescence dating techniques have progressed hand‐in‐hand over the past 25 years, with each subject informing the advancement of the other. This article considers the development and application of luminescence dating techniques to loess deposits from the early days of thermoluminescence (TL) to the optically stimulated luminescence (OSL) methods utilized today. Recent technological and methodological advances have led to a step‐change in the accuracy and precision of quartz OSL ages; this has led to an expansion of high‐resolution luminescence studies, which in turn are informing loess studies and challenging some of the basic ideas regarding the nature of loess records, their formation and their significance. Future luminescence research efforts are likely to focus on extending the age range of luminescence techniques, possibly by utilizing new luminescence signals; this, again, will allow investigation of the long‐term variability of loess records in comparison with other long records of climate change to which they are frequently compared.

@article{doi101111j15023885200800057x,
    author = "Roberts, Helen M.",
    title = "The development and application of luminescence dating to loess deposits: a perspective on the past, present and future",
    year = "2008",
    journal = "Boreas",
    abstract = "Loess deposits preserve important records of Quaternary climate change and atmospheric dust flux; however, their full significance can only be revealed once a reliable chronology is established. Our understanding of loess‐palaeosol sequences and the development of luminescence dating techniques have progressed hand‐in‐hand over the past 25 years, with each subject informing the advancement of the other. This article considers the development and application of luminescence dating techniques to loess deposits from the early days of thermoluminescence (TL) to the optically stimulated luminescence (OSL) methods utilized today. Recent technological and methodological advances have led to a step‐change in the accuracy and precision of quartz OSL ages; this has led to an expansion of high‐resolution luminescence studies, which in turn are informing loess studies and challenging some of the basic ideas regarding the nature of loess records, their formation and their significance. Future luminescence research efforts are likely to focus on extending the age range of luminescence techniques, possibly by utilizing new luminescence signals; this, again, will allow investigation of the long‐term variability of loess records in comparison with other long records of climate change to which they are frequently compared.",
    url = "https://doi.org/10.1111/j.1502-3885.2008.00057.x",
    doi = "10.1111/j.1502-3885.2008.00057.x",
    openalex = "W2061615113",
    references = "doi101016s0277379103001690"
}

ABSTRACT Thawing permafrost and the resulting microbial decomposition of previously frozen organic carbon (C) is one of the most significant potential feedbacks from terrestrial ecosystems to the atmosphere in a changing climate. In this article we present an overview of the global permafrost C pool and of the processes that might transfer this C into the atmosphere, as well as the associated ecosystem changes that occur with thawing. We show that accounting for C stored deep in the permafrost more than doubles previous high-latitude inventory estimates, with this new estimate equivalent to twice the atmospheric C pool. The thawing of permafrost with warming occurs both gradually and catastrophically, exposing organic C to microbial decomposition. Other aspects of ecosystem dynamics can be altered by climate change along with thawing permafrost, such as growing season length, plant growth rates and species composition, and ecosystem energy exchange. However, these processes do not appear to be able to compensate for C release from thawing permafrost, making it likely that the net effect of widespread permafrost thawing will be a positive feedback to a warming climate.

@article{doi101641b580807,
    author = "Schuur, Edward A. G. and Bockheim, James G. and Canadell, Josep G. and Euskirchen, E. S. and Field, Christopher B. and Goryachkin, S. V. and Hagemann, Stefan and Kuhry, Peter and Lafleur, Peter M. and Lee, Hanna and Mazhitova, G. G. and Nelson, Frederick E. and Rinke, Annette and Romanovsky, V. E. and Shiklomanov, N. I. and Tarnocai, C. and Venevsky, Sergey and Vogel, Jason G. and Zimov, Sergei A.",
    title = "Vulnerability of Permafrost Carbon to Climate Change: Implications for the Global Carbon Cycle",
    year = "2008",
    journal = "BioScience",
    abstract = "ABSTRACT Thawing permafrost and the resulting microbial decomposition of previously frozen organic carbon (C) is one of the most significant potential feedbacks from terrestrial ecosystems to the atmosphere in a changing climate. In this article we present an overview of the global permafrost C pool and of the processes that might transfer this C into the atmosphere, as well as the associated ecosystem changes that occur with thawing. We show that accounting for C stored deep in the permafrost more than doubles previous high-latitude inventory estimates, with this new estimate equivalent to twice the atmospheric C pool. The thawing of permafrost with warming occurs both gradually and catastrophically, exposing organic C to microbial decomposition. Other aspects of ecosystem dynamics can be altered by climate change along with thawing permafrost, such as growing season length, plant growth rates and species composition, and ecosystem energy exchange. However, these processes do not appear to be able to compensate for C release from thawing permafrost, making it likely that the net effect of widespread permafrost thawing will be a positive feedback to a warming climate.",
    url = "https://doi.org/10.1641/b580807",
    doi = "10.1641/b580807",
    openalex = "W2159200641",
    references = "doi101002ppp582, doi101016s1040618201000830, doi101017cbo9780511546013, doi101023a1005667424292, doi1010292006gl027484, doi101038386698a0, doi101038nature04514, doi101073pnas0400522101, doi101073pnas0702737104, doi10108010889370802175895, doi101126science1077445, doi101126science1082750, doi101126science1128908, doi101126science1142924, doi101175jcli38001, doi1018901051076120000100423tvdoso20co2, doi1023071941811, openalexw1520428197"
}

Abstract. Peatlands cover only 3% of the Earth's land surface but boreal and subarctic peatlands store about 15–30% of the world's soil carbon (C) as peat. Despite their potential for large positive feedbacks to the climate system through sequestration and emission of greenhouse gases, peatlands are not explicitly included in global climate models and therefore in predictions of future climate change. In April 2007 a symposium was held in Wageningen, the Netherlands, to advance our understanding of peatland C cycling. This paper synthesizes the main findings of the symposium, focusing on (i) small-scale processes, (ii) C fluxes at the landscape scale, and (iii) peatlands in the context of climate change. The main drivers controlling C fluxes are largely scale dependent and most are related to some aspects of hydrology. Despite high spatial and annual variability in Net Ecosystem Exchange (NEE), the differences in cumulative annual NEE are more a function of broad scale geographic location and physical setting than internal factors, suggesting the existence of strong feedbacks. In contrast, trace gas emissions seem mainly controlled by local factors. Key uncertainties remain concerning the existence of perturbation thresholds, the relative strengths of the CO2 and CH4 feedback, the links among peatland surface climate, hydrology, ecosystem structure and function, and trace gas biogeochemistry as well as the similarity of process rates across peatland types and climatic zones. Progress on these research areas can only be realized by stronger co-operation between disciplines that address different spatial and temporal scales.

@article{doi105194bg514752008,
    author = "Limpens, Juul and Berendse, Frank and Blodau, C. and Canadell, Josep G. and Freeman, Chris and Holden, Joseph and Roulet, Nigel T. and Rydin, H. and Schaepman‐Strub, Gabriela",
    title = "Peatlands and the carbon cycle: from local processes to global implications – a synthesis",
    year = "2008",
    journal = "Biogeosciences",
    abstract = "Abstract. Peatlands cover only 3\% of the Earth's land surface but boreal and subarctic peatlands store about 15–30\% of the world's soil carbon (C) as peat. Despite their potential for large positive feedbacks to the climate system through sequestration and emission of greenhouse gases, peatlands are not explicitly included in global climate models and therefore in predictions of future climate change. In April 2007 a symposium was held in Wageningen, the Netherlands, to advance our understanding of peatland C cycling. This paper synthesizes the main findings of the symposium, focusing on (i) small-scale processes, (ii) C fluxes at the landscape scale, and (iii) peatlands in the context of climate change. The main drivers controlling C fluxes are largely scale dependent and most are related to some aspects of hydrology. Despite high spatial and annual variability in Net Ecosystem Exchange (NEE), the differences in cumulative annual NEE are more a function of broad scale geographic location and physical setting than internal factors, suggesting the existence of strong feedbacks. In contrast, trace gas emissions seem mainly controlled by local factors. Key uncertainties remain concerning the existence of perturbation thresholds, the relative strengths of the CO2 and CH4 feedback, the links among peatland surface climate, hydrology, ecosystem structure and function, and trace gas biogeochemistry as well as the similarity of process rates across peatland types and climatic zones. Progress on these research areas can only be realized by stronger co-operation between disciplines that address different spatial and temporal scales.",
    url = "https://doi.org/10.5194/bg-5-1475-2008",
    doi = "10.5194/bg-5-1475-2008",
    openalex = "W2166363415",
    references = "doi101641b580807"
}

If radiocarbon measurements are to be used at all for chronological purposes, we have to use statistical methods for calibration. The most widely used method of calibration can be seen as a simple application of Bayesian statistics, which uses both the information from the new measurement and information from the 14 C calibration curve. In most dating applications, however, we have larger numbers of 14 C measurements and we wish to relate those to events in the past. Bayesian statistics provides a coherent framework in which such analysis can be performed and is becoming a core element in many 14 C dating projects. This article gives an overview of the main model components used in chronological analysis, their mathematical formulation, and examples of how such analyses can be performed using the latest version of the OxCal software (v4). Many such models can be put together, in a modular fashion, from simple elements, with defined constraints and groupings. In other cases, the commonly used “uniform phase” models might not be appropriate, and ramped, exponential, or normal distributions of events might be more useful. When considering analyses of these kinds, it is useful to be able run simulations on synthetic data. Methods for performing such tests are discussed here along with other methods of diagnosing possible problems with statistical models of this kind.

@article{doi101017s0033822200033865,
    author = "Ramsey, Christopher Bronk",
    title = "Bayesian Analysis of Radiocarbon Dates",
    year = "2009",
    journal = "Radiocarbon",
    abstract = "If radiocarbon measurements are to be used at all for chronological purposes, we have to use statistical methods for calibration. The most widely used method of calibration can be seen as a simple application of Bayesian statistics, which uses both the information from the new measurement and information from the 14 C calibration curve. In most dating applications, however, we have larger numbers of 14 C measurements and we wish to relate those to events in the past. Bayesian statistics provides a coherent framework in which such analysis can be performed and is becoming a core element in many 14 C dating projects. This article gives an overview of the main model components used in chronological analysis, their mathematical formulation, and examples of how such analyses can be performed using the latest version of the OxCal software (v4). Many such models can be put together, in a modular fashion, from simple elements, with defined constraints and groupings. In other cases, the commonly used “uniform phase” models might not be appropriate, and ramped, exponential, or normal distributions of events might be more useful. When considering analyses of these kinds, it is useful to be able run simulations on synthetic data. Methods for performing such tests are discussed here along with other methods of diagnosing possible problems with statistical models of this kind.",
    url = "https://doi.org/10.1017/s0033822200033865",
    doi = "10.1017/s0033822200033865",
    openalex = "W2167452694",
    references = "doi101016jquascirev200701019, doi101017s0033822200003672, doi101017s0033822200013904, doi101017s0033822200030903, doi101017s0033822200033154, doi101017s0033822200034093, doi101017s0033822200038212, doi10108001621459199010476213, doi101201b14835, openalexw1928750549"
}

The IntCal04 and Marine04 radiocarbon calibration curves have been updated from 12 cal kBP (cal kBP is here defined as thousands of calibrated years before AD 1950), and extended to 50 cal kBP, utilizing newly available data sets that meet the IntCal Working Group criteria for pristine corals and other carbonates and for quantification of uncertainty in both the 14 C and calendar timescales as established in 2002. No change was made to the curves from 0–12 cal kBP. The curves were constructed using a Markov chain Monte Carlo (MCMC) implementation of the random walk model used for IntCal04 and Marine04. The new curves were ratified at the 20th International Radiocarbon Conference in June 2009 and are available in the Supplemental Material at www.radiocarbon.org.

@article{doi101017s0033822200034202,
    author = "Reimer, Paula and Baillie, M. G. L. and Bard, Édouard and Bayliss, Alex and Beck, J Warren and Blackwell, Paul G. and Ramsey, Christopher Bronk and Buck, Caitlin E. and Burr, George S. and Edwards, R. Lawrence and Friedrich, Michael and Grootes, Pieter Meiert and Guilderson, T. P. and Hajdas, Irka and Heaton, Timothy and Hogg, Alan and Hughen, KA and Kaiser, Klaus Félix and Kromer, Bernd and McCormac, F. G. and Manning, Sturt W. and Reimer, Ron and Richards, David A. and Southon, John and Talamo, Sahra and Turney, Chris and van der Plicht, J. and Weyhenmeyer, C. E.",
    title = "IntCal09 and Marine09 Radiocarbon Age Calibration Curves, 0–50,000 Years cal BP",
    year = "2009",
    journal = "Radiocarbon",
    abstract = "The IntCal04 and Marine04 radiocarbon calibration curves have been updated from 12 cal kBP (cal kBP is here defined as thousands of calibrated years before AD 1950), and extended to 50 cal kBP, utilizing newly available data sets that meet the IntCal Working Group criteria for pristine corals and other carbonates and for quantification of uncertainty in both the 14 C and calendar timescales as established in 2002. No change was made to the curves from 0–12 cal kBP. The curves were constructed using a Markov chain Monte Carlo (MCMC) implementation of the random walk model used for IntCal04 and Marine04. The new curves were ratified at the 20th International Radiocarbon Conference in June 2009 and are available in the Supplemental Material at www.radiocarbon.org.",
    url = "https://doi.org/10.1017/s0033822200034202",
    doi = "10.1017/s0033822200034202",
    openalex = "W4211135859",
    references = "doi1010160012825272900384, doi101016jquascirev200504007, doi101017s0033822200003672, doi101017s0033822200013874, doi101017s0033822200019172, doi101017s0033822200032999, doi101017s0033822200033002, doi101038345405a0, doi101038364218a0, doi101038366552a0, doi101126science1064618, doi103402tellusav27i29900"
}

The Northern Circumpolar Soil Carbon Database was developed in order to determine carbon pools in soils of the northern circumpolar permafrost region. The area of all soils in the northern permafrost region is approximately 18,782 × 10 3 km 2, or approximately 16% of the global soil area. In the northern permafrost region, organic soils (peatlands) and cryoturbated permafrost‐affected mineral soils have the highest mean soil organic carbon contents (32.2–69.6 kg m −2). Here we report a new estimate of the carbon pools in soils of the northern permafrost region, including deeper layers and pools not accounted for in previous analyses. Carbon pools were estimated to be 191.29 Pg for the 0–30 cm depth, 495.80 Pg for the 0–100 cm depth, and 1024.00 Pg for the 0–300 cm depth. Our estimate for the first meter of soil alone is about double that reported for this region in previous analyses. Carbon pools in layers deeper than 300 cm were estimated to be 407 Pg in yedoma deposits and 241 Pg in deltaic deposits. In total, the northern permafrost region contains approximately 1672 Pg of organic carbon, of which approximately 1466 Pg, or 88%, occurs in perennially frozen soils and deposits. This 1672 Pg of organic carbon would account for approximately 50% of the estimated global belowground organic carbon pool.

@article{doi1010292008gb003327,
    author = "Tarnocai, C. and Canadell, Josep G. and Schuur, Edward A. G. and Kuhry, Peter and Mazhitova, G. G. and Zimov, S. A.",
    title = "Soil organic carbon pools in the northern circumpolar permafrost region",
    year = "2009",
    journal = "Global Biogeochemical Cycles",
    abstract = "The Northern Circumpolar Soil Carbon Database was developed in order to determine carbon pools in soils of the northern circumpolar permafrost region. The area of all soils in the northern permafrost region is approximately 18,782 × 10 3 km 2, or approximately 16\% of the global soil area. In the northern permafrost region, organic soils (peatlands) and cryoturbated permafrost‐affected mineral soils have the highest mean soil organic carbon contents (32.2–69.6 kg m −2). Here we report a new estimate of the carbon pools in soils of the northern permafrost region, including deeper layers and pools not accounted for in previous analyses. Carbon pools were estimated to be 191.29 Pg for the 0–30 cm depth, 495.80 Pg for the 0–100 cm depth, and 1024.00 Pg for the 0–300 cm depth. Our estimate for the first meter of soil alone is about double that reported for this region in previous analyses. Carbon pools in layers deeper than 300 cm were estimated to be 407 Pg in yedoma deposits and 241 Pg in deltaic deposits. In total, the northern permafrost region contains approximately 1672 Pg of organic carbon, of which approximately 1466 Pg, or 88\%, occurs in perennially frozen soils and deposits. This 1672 Pg of organic carbon would account for approximately 50\% of the estimated global belowground organic carbon pool.",
    url = "https://doi.org/10.1029/2008gb003327",
    doi = "10.1029/2008gb003327",
    openalex = "W1956280464",
    references = "doi101016s0016706100000975, doi101016s1040618201000830, doi1010292005gl024960, doi1010292006gl027484, doi101038298156a0, doi101038361520a0, doi101038nature04514, doi101111ejss121142, doi101111j136523891996tb01386x, doi101126science1128908, doi101175jcli38001, doi101641b580807, doi1018901051076120000100423tvdoso20co2, doi102136sssaj199303615995005700010034x, doi1023071941811"
}

Research over the past several decades has clarified the mechanisms and timescales involved in stabilizing organic matter in soils, but we still lack process-based understanding sufficient for predicting how vulnerable soil carbon (C) is, given climatic or environmental change across a range of soil types and landscapes. Part of the problem is the emphasis on short-term studies and processes that dominate C balance at the point or soil profile scale, whereas other processes that dominate over longer timescales and larger spatial scales may actually be more important for determining the carbon balance of soils in a region. Radiocarbon is one of the only tools to study the dynamics of C in soils on decadal to millennial timescales. It provides a means for directly testing models of organic matter dynamics in ecosystems and, when measured in respired CO 2 or dissolved organic carbon (DOC), provides evidence of shifts in microbial metabolism. This review explores the application of this underutilized tool, with an emphasis on conceptual advances made using the state-factor approach and on detecting processes causing abrupt change in soil C stores.

@article{doi101146annurevearth36031207124300,
    author = "Trumbore, Susan",
    title = "Radiocarbon and Soil Carbon Dynamics",
    year = "2009",
    journal = "Annual Review of Earth and Planetary Sciences",
    abstract = "Research over the past several decades has clarified the mechanisms and timescales involved in stabilizing organic matter in soils, but we still lack process-based understanding sufficient for predicting how vulnerable soil carbon (C) is, given climatic or environmental change across a range of soil types and landscapes. Part of the problem is the emphasis on short-term studies and processes that dominate C balance at the point or soil profile scale, whereas other processes that dominate over longer timescales and larger spatial scales may actually be more important for determining the carbon balance of soils in a region. Radiocarbon is one of the only tools to study the dynamics of C in soils on decadal to millennial timescales. It provides a means for directly testing models of organic matter dynamics in ecosystems and, when measured in respired CO 2 or dissolved organic carbon (DOC), provides evidence of shifts in microbial metabolism. This review explores the application of this underutilized tool, with an emphasis on conceptual advances made using the state-factor approach and on detecting processes causing abrupt change in soil C stores.",
    url = "https://doi.org/10.1146/annurev.earth.36.031207.124300",
    doi = "10.1146/annurev.earth.36.031207.124300",
    openalex = "W2130151136",
    references = "doi101016jgca200406005, doi101017s0033822200053066"
}

The recent warming in the Arctic is affecting a broad spectrum of physical, ecological, and human/cultural systems that may be irreversible on century time scales and have the potential to cause rapid changes in the earth system. The response of the carbon cycle of the Arctic to changes in climate is a major issue of global concern, yet there has not been a comprehensive review of the status of the contemporary carbon cycle of the Arctic and its response to climate change. This review is designed to clarify key uncertainties and vulnerabilities in the response of the carbon cycle of the Arctic to ongoing climatic change. While it is clear that there are substantial stocks of carbon in the Arctic, there are also significant uncertainties associated with the magnitude of organic matter stocks contained in permafrost and the storage of methane hydrates beneath both subterranean and submerged permafrost of the Arctic. In the context of the global carbon cycle, this review demonstrates that the Arctic plays an important role in the global dynamics of both CO 2 and CH 4. Studies suggest that the Arctic has been a sink for atmospheric CO 2 of between 0 and 0.8 Pg C/yr in recent decades, which is between 0% and 25% of the global net land/ocean flux during the 1990s. The Arctic is a substantial source of CH 4 to the atmosphere (between 32 and 112 Tg CH 4 /yr), primarily because of the large area of wetlands throughout the region. Analyses to date indicate that the sensitivity of the carbon cycle of the Arctic during the remainder of the 21st century is highly uncertain. To improve the capability to assess the sensitivity of the carbon cycle of the Arctic to projected climate change, we recommend that (1) integrated regional studies be conducted to link observations of carbon dynamics to the processes that are likely to influence those dynamics, and (2) the understanding gained from these integrated studies be incorporated into both uncoupled and fully coupled carbon–climate modeling efforts.

@article{doi1018900820251,
    author = "McGuire, A. David and Anderson, Leif G. and Christensen, Torben R. and Dallimore, S R and Guo, Laodong and Hayes, Daniel J. and Heimann, Martin and Lorenson, Thomas D. and Macdonald, Robie W. and Roulet, Nigel T.",
    title = "Sensitivity of the carbon cycle in the Arctic to climate change",
    year = "2009",
    journal = "Ecological Monographs",
    abstract = "The recent warming in the Arctic is affecting a broad spectrum of physical, ecological, and human/cultural systems that may be irreversible on century time scales and have the potential to cause rapid changes in the earth system. The response of the carbon cycle of the Arctic to changes in climate is a major issue of global concern, yet there has not been a comprehensive review of the status of the contemporary carbon cycle of the Arctic and its response to climate change. This review is designed to clarify key uncertainties and vulnerabilities in the response of the carbon cycle of the Arctic to ongoing climatic change. While it is clear that there are substantial stocks of carbon in the Arctic, there are also significant uncertainties associated with the magnitude of organic matter stocks contained in permafrost and the storage of methane hydrates beneath both subterranean and submerged permafrost of the Arctic. In the context of the global carbon cycle, this review demonstrates that the Arctic plays an important role in the global dynamics of both CO 2 and CH 4. Studies suggest that the Arctic has been a sink for atmospheric CO 2 of between 0 and 0.8 Pg C/yr in recent decades, which is between 0\% and 25\% of the global net land/ocean flux during the 1990s. The Arctic is a substantial source of CH 4 to the atmosphere (between 32 and 112 Tg CH 4 /yr), primarily because of the large area of wetlands throughout the region. Analyses to date indicate that the sensitivity of the carbon cycle of the Arctic during the remainder of the 21st century is highly uncertain. To improve the capability to assess the sensitivity of the carbon cycle of the Arctic to projected climate change, we recommend that (1) integrated regional studies be conducted to link observations of carbon dynamics to the processes that are likely to influence those dynamics, and (2) the understanding gained from these integrated studies be incorporated into both uncoupled and fully coupled carbon–climate modeling efforts.",
    url = "https://doi.org/10.1890/08-2025.1",
    doi = "10.1890/08-2025.1",
    openalex = "W2137745363",
    references = "doi101007bf00002772, doi101007s1002100690138, doi101007s1058400553522, doi101016jgloplacha200607028, doi1010292006gl027484, doi10102993gb02263, doi10102994gb00766, doi10103835041539, doi101046j13652486200300569x, doi101080014311600210191, doi10108010889370802175895, doi101111j136523891996tb01386x, doi101111j13652486200601128x, doi101126science1077445, doi101126science1128908, doi101126science2514991298, doi101126science26551781568, doi101175jcli38001, doi101641b580807, doi1018901051076120000100423tvdoso20co2, doi1023071941811, doi105860choice455008"
}

Abstract Carbon dioxide (CO2) is sequestered through the weathering and subsequent mineralization of the chrysotile mine tailings at Clinton Creek, Yukon Territory, and Cassiar, British Columbia, Canada. Accelerated weathering is attributed to a dramatic increase in surface area, which occurs during the milling of ore. We provide a detailed account of the natural process of carbon trapping and storage as it occurs at Clinton Creek and Cassiar, including mineralogy, modes of occurrence, methods of formation for carbonate alteration, light stable isotope geochemistry, and radiocarbon analysis. Powder X-ray diffraction data were used to identify weathering products as the hydrated magnesium carbonate minerals nesquehonite [MgCO3·3H2O], dypingite [Mg5(CO3)4 (OH)2·5H2O], hydromagnesite [Mg5(CO3)4(OH)2·4H2O], and less commonly lansfordite [MgCO3·5H2O]. Textural relationships suggest that carbonate precipitates formed in situ after milling and deposition of tailings. Samples of efflorescent nesquehonite are characterized by δ13C values between 6.52 and 14.36 per mil, δ18O values between 20.93 and 26.62 per mil, and F14C values (fraction of modern carbon) between 1.072 and 1.114, values which are consistent with temperature-dependent fractionation of modern atmospheric CO2 during mineralization. Samples of dypingite ± hydromagnesite collected from within 0.2 m of the tailings surface give δ13C values between −1.51 and +10.02 per mil, δ18O values between +17.53 and +28.40 per mil, and F14C values between 1.026 and 1.146, which suggests precipitation from modern atmospheric CO2 in a soil-like environment. Field observations and isotopic data suggest that hydrated magnesium carbonate minerals formed in two environments. Nesquehonite formed in an evaporative environment on the surface of tailings piles, and dypingite and hydromagnesite formed in the subsurface environment with characteristics similar to soil carbonate. In both cases, these minerals have been trapping and storing the greenhouse gas, CO2, directly from the atmosphere. Combined use of δ13C, δ18O, and F14C data has been applied effectively as a tool for verifying and monitoring sequestration of atmospheric CO2 within mine tailings. A number of other deposit types produce tailings suitable for CO2 sequestration, including Cu-Ni-PGE deposits, diamondiferous kimberlite pipes, and podiform chromite deposits. Our results suggest that conversion of about 10 wt percent of tailings to carbonate minerals could offset the greenhouse gas emissions from many ultramafic-hosted mining operations.

@article{doi102113gsecongeo104195,
    author = "Wilson, Sasha and Dipple, Gregory M. and Power, Ian and Thom, J. and Anderson, Robert and Raudsepp, Mati and Gabites, Janet and Southam, Gordon",
    title = "Carbon Dioxide Fixation within Mine Wastes of Ultramafic-Hosted Ore Deposits: Examples from the Clinton Creek and Cassiar Chrysotile Deposits, Canada",
    year = "2009",
    journal = "Economic Geology",
    abstract = "Abstract Carbon dioxide (CO2) is sequestered through the weathering and subsequent mineralization of the chrysotile mine tailings at Clinton Creek, Yukon Territory, and Cassiar, British Columbia, Canada. Accelerated weathering is attributed to a dramatic increase in surface area, which occurs during the milling of ore. We provide a detailed account of the natural process of carbon trapping and storage as it occurs at Clinton Creek and Cassiar, including mineralogy, modes of occurrence, methods of formation for carbonate alteration, light stable isotope geochemistry, and radiocarbon analysis. Powder X-ray diffraction data were used to identify weathering products as the hydrated magnesium carbonate minerals nesquehonite [MgCO3·3H2O], dypingite [Mg5(CO3)4 (OH)2·5H2O], hydromagnesite [Mg5(CO3)4(OH)2·4H2O], and less commonly lansfordite [MgCO3·5H2O]. Textural relationships suggest that carbonate precipitates formed in situ after milling and deposition of tailings. Samples of efflorescent nesquehonite are characterized by δ13C values between 6.52 and 14.36 per mil, δ18O values between 20.93 and 26.62 per mil, and F14C values (fraction of modern carbon) between 1.072 and 1.114, values which are consistent with temperature-dependent fractionation of modern atmospheric CO2 during mineralization. Samples of dypingite ± hydromagnesite collected from within 0.2 m of the tailings surface give δ13C values between −1.51 and +10.02 per mil, δ18O values between +17.53 and +28.40 per mil, and F14C values between 1.026 and 1.146, which suggests precipitation from modern atmospheric CO2 in a soil-like environment. Field observations and isotopic data suggest that hydrated magnesium carbonate minerals formed in two environments. Nesquehonite formed in an evaporative environment on the surface of tailings piles, and dypingite and hydromagnesite formed in the subsurface environment with characteristics similar to soil carbonate. In both cases, these minerals have been trapping and storing the greenhouse gas, CO2, directly from the atmosphere. Combined use of δ13C, δ18O, and F14C data has been applied effectively as a tool for verifying and monitoring sequestration of atmospheric CO2 within mine tailings. A number of other deposit types produce tailings suitable for CO2 sequestration, including Cu-Ni-PGE deposits, diamondiferous kimberlite pipes, and podiform chromite deposits. Our results suggest that conversion of about 10 wt percent of tailings to carbonate minerals could offset the greenhouse gas emissions from many ultramafic-hosted mining operations.",
    url = "https://doi.org/10.2113/gsecongeo.104.1.95",
    doi = "10.2113/gsecongeo.104.1.95",
    openalex = "W2104664138",
    references = "doi101017s0033822200040121"
}

We explore the role of lakes in carbon cycling and global climate, examine the mechanisms influencing carbon pools and transformations in lakes, and discuss how the metabolism of carbon in the inland waters is likely to change in response to climate. Furthermore, we project changes as global climate change in the abundance and spatial distribution of lakes in the biosphere, and we revise the estimate for the global extent of carbon transformation in inland waters. This synthesis demonstrates that the global annual emissions of carbon dioxide from inland waters to the atmosphere are similar in magnitude to the carbon dioxide uptake by the oceans and that the global burial of organic carbon in inland water sediments exceeds organic carbon sequestration on the ocean floor. The role of inland waters in global carbon cycling and climate forcing may be changed by human activities, including construction of impoundments, which accumulate large amounts of carbon in sediments and emit large amounts of methane to the atmosphere. Methane emissions are also expected from lakes on melting permafrost. The synthesis presented here indicates that (1) inland waters constitute a significant component of the global carbon cycle, (2) their contribution to this cycle has significantly changed as a result of human activities, and (3) they will continue to change in response to future climate change causing decreased as well as increased abundance of lakes as well as increases in the number of aquatic impoundments.

@article{doi104319lo2009546part22298,
    author = "Tranvik, Lars J. and Downing, John and Cotner, James B. and Loiselle, Steven and Striegl, Robert G. and Ballatore, Thomas J. and Dillon, Peter J. and Finlay, Kerri and Fortino, Kenneth and Knoll, Lesley B. and Kortelainen, Pirkko and Kutser, Tiit and Larsen, Søren Erik and Laurion, Isabelle and Leech, Dina M. and McCallister, S. Leigh and McKnight, Diane M. and Mélack, John M. and Overholt, Erin P. and Porter, Jason A. and Prairie, Yves T. and Renwick, William H. and Roland, Fábio and Sherman, Bradford and Schindler, David W. and Sobek, Sebastian and Tremblay, Alain and Vanni, Michael J. and Verschoor, Antonie M. and von Wachenfeldt, Eddie and Weyhenmeyer, Gesa A.",
    title = "Lakes and reservoirs as regulators of carbon cycling and climate",
    year = "2009",
    journal = "Limnology and Oceanography",
    abstract = "We explore the role of lakes in carbon cycling and global climate, examine the mechanisms influencing carbon pools and transformations in lakes, and discuss how the metabolism of carbon in the inland waters is likely to change in response to climate. Furthermore, we project changes as global climate change in the abundance and spatial distribution of lakes in the biosphere, and we revise the estimate for the global extent of carbon transformation in inland waters. This synthesis demonstrates that the global annual emissions of carbon dioxide from inland waters to the atmosphere are similar in magnitude to the carbon dioxide uptake by the oceans and that the global burial of organic carbon in inland water sediments exceeds organic carbon sequestration on the ocean floor. The role of inland waters in global carbon cycling and climate forcing may be changed by human activities, including construction of impoundments, which accumulate large amounts of carbon in sediments and emit large amounts of methane to the atmosphere. Methane emissions are also expected from lakes on melting permafrost. The synthesis presented here indicates that (1) inland waters constitute a significant component of the global carbon cycle, (2) their contribution to this cycle has significantly changed as a result of human activities, and (3) they will continue to change in response to future climate change causing decreased as well as increased abundance of lakes as well as increases in the number of aquatic impoundments.",
    url = "https://doi.org/10.4319/lo.2009.54.6\_part\_2.2298",
    doi = "10.4319/lo.2009.54.6\_part\_2.2298",
    openalex = "W2108686678",
    references = "doi101016s0016703798000441, doi101126science1128908, doi101126science2514991298, doi101126science26551781568"
}

A broad compilation of modern carbon isotope compositions in all C3 plant types shows a monotonic increase in δ(13)C with decreasing mean annual precipitation (MAP) that differs from previous models. Corrections for temperature, altitude, or latitude are smaller than previously estimated. As corrected for altitude, latitude, and the δ(13)C of atmospheric CO(2), these data permit refined interpretation of MAP, paleodiet, and paleoecology of ecosystems dominated by C3 plants, either prior to 7-8 million years ago (Ma), or more recently at mid- to high latitudes. Twenty-nine published paleontological studies suggest preservational or scientific bias toward dry ecosystems, although wet ecosystems are also represented. Unambiguous isotopic evidence for C4 plants is lacking prior to 7-8 Ma, and hominid ecosystems at 4.4 Ma show no isotopic evidence for dense forests. Consideration of global plant biomass indicates that average δ(13)C of C3 plants is commonly overestimated by approximately 2‰.

@article{doi101073pnas1004933107,
    author = "Kohn, Matthew J.",
    title = "Carbon isotope compositions of terrestrial C3 plants as indicators of (paleo)ecology and (paleo)climate",
    year = "2010",
    journal = "Proceedings of the National Academy of Sciences",
    abstract = "A broad compilation of modern carbon isotope compositions in all C3 plant types shows a monotonic increase in δ(13)C with decreasing mean annual precipitation (MAP) that differs from previous models. Corrections for temperature, altitude, or latitude are smaller than previously estimated. As corrected for altitude, latitude, and the δ(13)C of atmospheric CO(2), these data permit refined interpretation of MAP, paleodiet, and paleoecology of ecosystems dominated by C3 plants, either prior to 7-8 million years ago (Ma), or more recently at mid- to high latitudes. Twenty-nine published paleontological studies suggest preservational or scientific bias toward dry ecosystems, although wet ecosystems are also represented. Unambiguous isotopic evidence for C4 plants is lacking prior to 7-8 Ma, and hominid ecosystems at 4.4 Ma show no isotopic evidence for dense forests. Consideration of global plant biomass indicates that average δ(13)C of C3 plants is commonly overestimated by approximately 2‰.",
    url = "https://doi.org/10.1073/pnas.1004933107",
    doi = "10.1073/pnas.1004933107",
    openalex = "W2106990564",
    references = "doi101002oa662, doi101007bf00377062, doi101007s004420050868, doi1010292001gb001807, doi10103838229, doi101073pnas0910513107, doi101126science1110063, doi101146annurevearth261573, doi101146annurevecolsys33020602095451, doi101146annurevpp40060189002443, doi1023071310735"
}

The historical chronologies for dynastic Egypt are based on reign lengths inferred from written and archaeological evidence. These floating chronologies are linked to the absolute calendar by a few ancient astronomical observations, which remain a source of debate. We used 211 radiocarbon measurements made on samples from short-lived plants, together with a Bayesian model incorporating historical information on reign lengths, to produce a chronology for dynastic Egypt. A small offset (19 radiocarbon years older) in radiocarbon levels in the Nile Valley is probably a growing-season effect. Our radiocarbon data indicate that the New Kingdom started between 1570 and 1544 B.C.E., and the reign of Djoser in the Old Kingdom started between 2691 and 2625 B.C.E.; both cases are earlier than some previous historical estimates.

@article{doi101126science1189395,
    author = "Ramsey, Christopher Bronk and Dee, Michael and Rowland, Joanne and Higham, Thomas and Harris, Stephen A. and Brock, Fiona and Quilès, Anita and Wild, Eva Maria and Marcus, Ezra S. and Shortland, Andrew",
    title = "Radiocarbon-Based Chronology for Dynastic Egypt",
    year = "2010",
    journal = "Science",
    abstract = "The historical chronologies for dynastic Egypt are based on reign lengths inferred from written and archaeological evidence. These floating chronologies are linked to the absolute calendar by a few ancient astronomical observations, which remain a source of debate. We used 211 radiocarbon measurements made on samples from short-lived plants, together with a Bayesian model incorporating historical information on reign lengths, to produce a chronology for dynastic Egypt. A small offset (19 radiocarbon years older) in radiocarbon levels in the Nile Valley is probably a growing-season effect. Our radiocarbon data indicate that the New Kingdom started between 1570 and 1544 B.C.E., and the reign of Djoser in the Old Kingdom started between 2691 and 2625 B.C.E.; both cases are earlier than some previous historical estimates.",
    url = "https://doi.org/10.1126/science.1189395",
    doi = "10.1126/science.1189395",
    openalex = "W2032787368",
    references = "doi101126science1125087"
}

The IntCal09 and Marine09 radiocarbon calibration curves have been revised utilizing newly available and updated data sets from 14 C measurements on tree rings, plant macrofossils, speleothems, corals, and foraminifera. The calibration curves were derived from the data using the random walk model (RWM) used to generate IntCal09 and Marine09, which has been revised to account for additional uncertainties and error structures. The new curves were ratified at the 21st International Radiocarbon conference in July 2012 and are available as Supplemental Material at www.radiocarbon.org. The database can be accessed at http://intcal.qub.ac.uk/intcal13/.

@article{doi102458azujsrc5516947,
    author = "Reimer, Paula J and Bard, Edouard and Bayliss, Alex and Beck, J Warren and Blackwell, Paul G and Ramsey, Christopher Bronk and Buck, Caitlin E and Cheng, Hai and Edwards, R Lawrence and Friedrich, Michael and Grootes, Pieter M and Guilderson, Thomas P and Haflidason, Haflidi and Hajdas, Irka and Hatté, Christine and Heaton, Timothy J and Hoffmann, Dirk L and Hogg, Alan G and Hughen, Konrad A and Kaiser, K Felix and Kromer, Bernd and Manning, Sturt W and Niu, Mu and Reimer, Ron W and Richards, David A and Scott, E Marian and Southon, John R and Staff, Richard A and Turney, Christian S M and van der Plicht, Johannes",
    title = "IntCal13 and Marine13 Radiocarbon Age Calibration Curves 0–50,000 Years cal BP",
    year = "2010",
    journal = "Radiocarbon",
    abstract = "The IntCal09 and Marine09 radiocarbon calibration curves have been revised utilizing newly available and updated data sets from 14 C measurements on tree rings, plant macrofossils, speleothems, corals, and foraminifera. The calibration curves were derived from the data using the random walk model (RWM) used to generate IntCal09 and Marine09, which has been revised to account for additional uncertainties and error structures. The new curves were ratified at the 21st International Radiocarbon conference in July 2012 and are available as Supplemental Material at www.radiocarbon.org. The database can be accessed at http://intcal.qub.ac.uk/intcal13/.",
    url = "https://doi.org/10.2458/azu\_js\_rc.55.16947",
    doi = "10.2458/azu\_js\_rc.55.16947",
    openalex = "W2146687568",
    references = "doi101017s0033822200013874, doi101017s0033822200033002, doi101017s0033822200034202, doi101038345405a0, doi101038nature02494, doi101038nature11123, doi101126science1226660, doi101126science27953541187, doi101126science28954831321, doi102458azujsrc5516783, doi102458azujsrc5516955, doi103402tellusav27i29900, doi105194cp4472008"
}

Radiocarbon ((14)C) provides a way to date material that contains carbon with an age up to ~50,000 years and is also an important tracer of the global carbon cycle. However, the lack of a comprehensive record reflecting atmospheric (14)C prior to 12.5 thousand years before the present (kyr B.P.) has limited the application of radiocarbon dating of samples from the Last Glacial period. Here, we report (14)C results from Lake Suigetsu, Japan (35°35'N, 135°53'E), which provide a comprehensive record of terrestrial radiocarbon to the present limit of the (14)C method. The time scale we present in this work allows direct comparison of Lake Suigetsu paleoclimatic data with other terrestrial climatic records and gives information on the connection between global atmospheric and regional marine radiocarbon levels.

@article{doi101126science1226660,
    author = "Ramsey, Christopher Bronk and Staff, Richard A. and Bryant, Charlotte and Brock, Fiona and Kitagawa, Hiroyuki and van der Plicht, J. and Schlolaut, Gordon and Marshall, Michael and Brauer, Achim and Lamb, Henry F. and Payne, Rebecca and Tarasov, Pavel E. and Haraguchi, Tsuyoshi and Gotanda, Katsuya and Yonenobu, Hitoshi and Yokoyama, Yūsuke and Tada, Ryuji and Nakagawa, Takeshi",
    title = "A Complete Terrestrial Radiocarbon Record for 11.2 to 52.8 kyr B.P.",
    year = "2012",
    journal = "Science",
    abstract = "Radiocarbon ((14)C) provides a way to date material that contains carbon with an age up to \textasciitilde 50,000 years and is also an important tracer of the global carbon cycle. However, the lack of a comprehensive record reflecting atmospheric (14)C prior to 12.5 thousand years before the present (kyr B.P.) has limited the application of radiocarbon dating of samples from the Last Glacial period. Here, we report (14)C results from Lake Suigetsu, Japan (35°35'N, 135°53'E), which provide a comprehensive record of terrestrial radiocarbon to the present limit of the (14)C method. The time scale we present in this work allows direct comparison of Lake Suigetsu paleoclimatic data with other terrestrial climatic records and gives information on the connection between global atmospheric and regional marine radiocarbon levels.",
    url = "https://doi.org/10.1126/science.1226660",
    doi = "10.1126/science.1226660",
    openalex = "W2037304784",
    references = "doi101016jquascirev200501012, doi101016jquascirev200504007, doi101016jquascirev200603014, doi101016jquascirev200701019, doi101016jquascirev201111022, doi101016s1040618299000142, doi101017s0033822200034202, doi101038ngeo128, doi101111j147547541978tb00208x, doi105194cp4472008"
}

Abstract The physical climate formulation and simulation characteristics of two new global coupled carbon–climate Earth System Models, ESM2M and ESM2G, are described. These models demonstrate similar climate fidelity as the Geophysical Fluid Dynamics Laboratory’s previous Climate Model version 2.1 (CM2.1) while incorporating explicit and consistent carbon dynamics. The two models differ exclusively in the physical ocean component; ESM2M uses Modular Ocean Model version 4p1 with vertical pressure layers while ESM2G uses Generalized Ocean Layer Dynamics with a bulk mixed layer and interior isopycnal layers. Differences in the ocean mean state include the thermocline depth being relatively deep in ESM2M and relatively shallow in ESM2G compared to observations. The crucial role of ocean dynamics on climate variability is highlighted in El Niño–Southern Oscillation being overly strong in ESM2M and overly weak in ESM2G relative to observations. Thus, while ESM2G might better represent climate changes relating to total heat content variability given its lack of long-term drift, gyre circulation, and ventilation in the North Pacific, tropical Atlantic, and Indian Oceans, and depth structure in the overturning and abyssal flows, ESM2M might better represent climate changes relating to surface circulation given its superior surface temperature, salinity, and height patterns, tropical Pacific circulation and variability, and Southern Ocean dynamics. The overall assessment is that neither model is fundamentally superior to the other, and that both models achieve sufficient fidelity to allow meaningful climate and earth system modeling applications. This affords the ability to assess the role of ocean configuration on earth system interactions in the context of two state-of-the-art coupled carbon–climate models.

@article{doi101175jclid11005601,
    author = "Dunne, John P. and John, Jasmin G. and Adcroft, Alistair and Griffies, Stephen M. and Hallberg, Robert and Shevliakova, Elena and Stouffer, Ronald J. and Cooke, William and Dunne, K. A. and Harrison, Matthew and Krasting, John P. and Malyshev, Sergey and Milly, P. C. D. and Phillipps, Peter J. and Sentman, Lori T. and Samuels, Bonita L. and Spelman, Michael J. and Winton, Michael and Wittenberg, Andrew T. and Zadeh, Niki",
    title = "GFDL’s ESM2 Global Coupled Climate–Carbon Earth System Models. Part I: Physical Formulation and Baseline Simulation Characteristics",
    year = "2012",
    journal = "Journal of Climate",
    abstract = "Abstract The physical climate formulation and simulation characteristics of two new global coupled carbon–climate Earth System Models, ESM2M and ESM2G, are described. These models demonstrate similar climate fidelity as the Geophysical Fluid Dynamics Laboratory’s previous Climate Model version 2.1 (CM2.1) while incorporating explicit and consistent carbon dynamics. The two models differ exclusively in the physical ocean component; ESM2M uses Modular Ocean Model version 4p1 with vertical pressure layers while ESM2G uses Generalized Ocean Layer Dynamics with a bulk mixed layer and interior isopycnal layers. Differences in the ocean mean state include the thermocline depth being relatively deep in ESM2M and relatively shallow in ESM2G compared to observations. The crucial role of ocean dynamics on climate variability is highlighted in El Niño–Southern Oscillation being overly strong in ESM2M and overly weak in ESM2G relative to observations. Thus, while ESM2G might better represent climate changes relating to total heat content variability given its lack of long-term drift, gyre circulation, and ventilation in the North Pacific, tropical Atlantic, and Indian Oceans, and depth structure in the overturning and abyssal flows, ESM2M might better represent climate changes relating to surface circulation given its superior surface temperature, salinity, and height patterns, tropical Pacific circulation and variability, and Southern Ocean dynamics. The overall assessment is that neither model is fundamentally superior to the other, and that both models achieve sufficient fidelity to allow meaningful climate and earth system modeling applications. This affords the ability to assess the role of ocean configuration on earth system interactions in the context of two state-of-the-art coupled carbon–climate models.",
    url = "https://doi.org/10.1175/jcli-d-11-00560.1",
    doi = "10.1175/jcli-d-11-00560.1",
    openalex = "W2110669521",
    references = "doi101016jdsr2200812009, doi1010292004gb002247, openalexw1909570941"
}

The new Max‐Planck‐Institute Earth System Model (MPI‐ESM) is used in the Coupled Model Intercomparison Project phase 5 (CMIP5) in a series of climate change experiments for either idealized CO 2 ‐only forcing or forcings based on observations and the Representative Concentration Pathway (RCP) scenarios. The paper gives an overview of the model configurations, experiments related forcings, and initialization procedures and presents results for the simulated changes in climate and carbon cycle. It is found that the climate feedback depends on the global warming and possibly the forcing history. The global warming from climatological 1850 conditions to 2080–2100 ranges from 1.5°C under the RCP2.6 scenario to 4.4°C under the RCP8.5 scenario. Over this range, the patterns of temperature and precipitation change are nearly independent of the global warming. The model shows a tendency to reduce the ocean heat uptake efficiency toward a warmer climate, and hence acceleration in warming in the later years. The precipitation sensitivity can be as high as 2.5% K −1 if the CO 2 concentration is constant, or as small as 1.6% K −1, if the CO 2 concentration is increasing. The oceanic uptake of anthropogenic carbon increases over time in all scenarios, being smallest in the experiment forced by RCP2.6 and largest in that for RCP8.5. The land also serves as a net carbon sink in all scenarios, predominantly in boreal regions. The strong tropical carbon sources found in the RCP2.6 and RCP8.5 experiments are almost absent in the RCP4.5 experiment, which can be explained by reforestation in the RCP4.5 scenario.

@article{doi101002jame20038,
    author = "Giorgetta, M. A. and Jungclaus, Johann and Reick, Christian H. and Legutke, Stephanie and Bader, Jürgen and Böttinger, Michael and Brovkin, Victor and Crueger, Traute and Esch, Monika and Fieg, Kerstin and Glushak, Ksenia and Gayler, Veronika and Haak, Helmuth and Hollweg, Heinz‐Dieter and Ilyina, Tatiana and Kinne, Stefan and Kornblueh, Luis and Matei, Daniela and Mauritsen, Thorsten and Mikolajewicz, Uwe and Mueller, Wolfgang and Notz, Dirk and Pithan, Felix and Raddatz, Thomas and Rast, Sebastian and Redler, René and Roeckner, E. and Schmidt, Hauke and Schnur, Reiner and Segschneider, Joachim and Six, Katharina and Stockhause, Martina and Timmreck, Claudia and Wegner, Jörg and Widmann, Heinrich and Wieners, Karl‐H. and Claußen, Martin and Marotzke, Jochem and Stevens, Björn",
    title = "Climate and carbon cycle changes from 1850 to 2100 in MPI‐ESM simulations for the Coupled Model Intercomparison Project phase 5",
    year = "2013",
    journal = "Journal of Advances in Modeling Earth Systems",
    abstract = "The new Max‐Planck‐Institute Earth System Model (MPI‐ESM) is used in the Coupled Model Intercomparison Project phase 5 (CMIP5) in a series of climate change experiments for either idealized CO 2 ‐only forcing or forcings based on observations and the Representative Concentration Pathway (RCP) scenarios. The paper gives an overview of the model configurations, experiments related forcings, and initialization procedures and presents results for the simulated changes in climate and carbon cycle. It is found that the climate feedback depends on the global warming and possibly the forcing history. The global warming from climatological 1850 conditions to 2080–2100 ranges from 1.5°C under the RCP2.6 scenario to 4.4°C under the RCP8.5 scenario. Over this range, the patterns of temperature and precipitation change are nearly independent of the global warming. The model shows a tendency to reduce the ocean heat uptake efficiency toward a warmer climate, and hence acceleration in warming in the later years. The precipitation sensitivity can be as high as 2.5\% K −1 if the CO 2 concentration is constant, or as small as 1.6\% K −1, if the CO 2 concentration is increasing. The oceanic uptake of anthropogenic carbon increases over time in all scenarios, being smallest in the experiment forced by RCP2.6 and largest in that for RCP8.5. The land also serves as a net carbon sink in all scenarios, predominantly in boreal regions. The strong tropical carbon sources found in the RCP2.6 and RCP8.5 experiments are almost absent in the RCP4.5 experiment, which can be explained by reforestation in the RCP4.5 scenario.",
    url = "https://doi.org/10.1002/jame.20038",
    doi = "10.1002/jame.20038",
    openalex = "W1544875105",
    references = "doi101007s105840110156z, doi1010292004gb002247, doi1015159780295741406007"
}

Stable carbon isotope ratios (δ(13) C) of terrestrial plants are employed across a diverse range of applications in environmental and plant sciences; however, the kind of information that is desired from the δ(13) C signal often differs. At the extremes, it ranges between purely environmental and purely biological. Here, we review environmental drivers of variation in carbon isotope discrimination (Δ) in terrestrial plants, and the biological processes that can either damp or amplify the response. For C3 plants, where Δ is primarily controlled by the ratio of intercellular to ambient CO2 concentrations (ci /ca), coordination between stomatal conductance and photosynthesis and leaf area adjustment tends to constrain the potential environmentally driven range of Δ. For C4 plants, variation in bundle-sheath leakiness to CO2 can either damp or amplify the effects of ci /ca on Δ. For plants with crassulacean acid metabolism (CAM), Δ varies over a relatively large range as a function of the proportion of daytime to night-time CO2 fixation. This range can be substantially broadened by environmental effects on Δ when carbon uptake takes place primarily during the day. The effective use of Δ across its full range of applications will require a holistic view of the interplay between environmental control and physiological modulation of the environmental signal.

@article{doi101111nph12423,
    author = "Cernusak, Lucas A. and Ubierna, Nerea and Winter, Klaus and Holtum, Joseph A. M. and Marshall, John D. and Farquhar, Graham D.",
    title = "Environmental and physiological determinants of carbon isotope discrimination in terrestrial plants",
    year = "2013",
    journal = "New Phytologist",
    abstract = "Stable carbon isotope ratios (δ(13) C) of terrestrial plants are employed across a diverse range of applications in environmental and plant sciences; however, the kind of information that is desired from the δ(13) C signal often differs. At the extremes, it ranges between purely environmental and purely biological. Here, we review environmental drivers of variation in carbon isotope discrimination (Δ) in terrestrial plants, and the biological processes that can either damp or amplify the response. For C3 plants, where Δ is primarily controlled by the ratio of intercellular to ambient CO2 concentrations (ci /ca), coordination between stomatal conductance and photosynthesis and leaf area adjustment tends to constrain the potential environmentally driven range of Δ. For C4 plants, variation in bundle-sheath leakiness to CO2 can either damp or amplify the effects of ci /ca on Δ. For plants with crassulacean acid metabolism (CAM), Δ varies over a relatively large range as a function of the proportion of daytime to night-time CO2 fixation. This range can be substantially broadened by environmental effects on Δ when carbon uptake takes place primarily during the day. The effective use of Δ across its full range of applications will require a holistic view of the interplay between environmental control and physiological modulation of the environmental signal.",
    url = "https://doi.org/10.1111/nph.12423",
    doi = "10.1111/nph.12423",
    openalex = "W2171137015",
    references = "doi101073pnas1004933107"
}

Abstract The freshwater reservoir effect can result in anomalously old radiocarbon ages of samples from lakes and rivers. This includes the bones of people whose subsistence was based on freshwater fish, and pottery in which fish was cooked. Water rich in dissolved ancient calcium carbonates, commonly known as hard water, is the most common reason for the freshwater reservoir effect. It is therefore also called hardwater effect. Although it has been known for more than 60 years, it is still less well-recognized by archaeologists than the marine reservoir effect. The aim of this study is to examine the order of magnitude and degree of variability of the freshwater reservoir effect over short and long timescales. Radiocarbon dating of recent water samples, aquatic plants, and animals, shows that age differences of up to 2000 14 C years can occur within one river. The freshwater reservoir effect has also implications for radiocarbon dating of Mesolithic pottery from inland sites of the Ertebølle culture in Northern Germany. The surprisingly old ages of the earliest pottery most probably are caused by a freshwater reservoir effect. In a sediment core from the Limfjord, northern Denmark, the impact of the freshwater reservoir effect on radiocarbon dating in an estuarine environment is examined. Here, freshwater influence causes reservoir ages to vary between 250 and 700 14 C years during the period 5400 BC - AD 700. The examples in this study show clearly that the freshwater reservoir effect can seriously corrupt radiocarbon dating at inland sites. Reservoir effects should therefore be considered whenever food remains on pottery or the bones of omnivores are radiocarbon dated - irrespective of the site’s distance to the coast.

@article{doi10118620507445124,
    author = "Philippsen, Bente",
    title = "The freshwater reservoir effect in radiocarbon dating",
    year = "2013",
    journal = "Heritage Science",
    abstract = "Abstract The freshwater reservoir effect can result in anomalously old radiocarbon ages of samples from lakes and rivers. This includes the bones of people whose subsistence was based on freshwater fish, and pottery in which fish was cooked. Water rich in dissolved ancient calcium carbonates, commonly known as hard water, is the most common reason for the freshwater reservoir effect. It is therefore also called hardwater effect. Although it has been known for more than 60 years, it is still less well-recognized by archaeologists than the marine reservoir effect. The aim of this study is to examine the order of magnitude and degree of variability of the freshwater reservoir effect over short and long timescales. Radiocarbon dating of recent water samples, aquatic plants, and animals, shows that age differences of up to 2000 14 C years can occur within one river. The freshwater reservoir effect has also implications for radiocarbon dating of Mesolithic pottery from inland sites of the Ertebølle culture in Northern Germany. The surprisingly old ages of the earliest pottery most probably are caused by a freshwater reservoir effect. In a sediment core from the Limfjord, northern Denmark, the impact of the freshwater reservoir effect on radiocarbon dating in an estuarine environment is examined. Here, freshwater influence causes reservoir ages to vary between 250 and 700 14 C years during the period 5400 BC - AD 700. The examples in this study show clearly that the freshwater reservoir effect can seriously corrupt radiocarbon dating at inland sites. Reservoir effects should therefore be considered whenever food remains on pottery or the bones of omnivores are radiocarbon dated - irrespective of the site’s distance to the coast.",
    url = "https://doi.org/10.1186/2050-7445-1-24",
    doi = "10.1186/2050-7445-1-24",
    openalex = "W2038887123",
    references = "doi101007030647669x10"
}

High-quality data from appropriate archives are needed for the continuing improvement of radiocarbon calibration curves. We discuss here the basic assumptions behind 14 C dating that necessitate calibration and the relative strengths and weaknesses of archives from which calibration data are obtained. We also highlight the procedures, problems, and uncertainties involved in determining atmospheric and surface ocean 14 C/ 12 C in these archives, including a discussion of the various methods used to derive an independent absolute timescale and uncertainty. The types of data required for the current IntCal database and calibration curve model are tabulated with examples.

@article{doi102458azujsrc5516955,
    author = "Reimer, Paula and Bard, Édouard and Bayliss, Alex and Beck, J Warren and Blackwell, Paul G. and Ramsey, Christopher Bronk and Brown, David and Buck, Caitlin E. and Edwards, R. Lawrence and Friedrich, Michael and Grootes, Pieter Meiert and Guilderson, T. P. and Haflidason, Haflidi and Hajdas, Irka and Hatté, Christine and Heaton, Timothy and Hogg, Alan and Hughen, Konrad A and Kaiser, Klaus Félix and Kromer, Bernd and Manning, Sturt W. and Reimer, Ron and Richards, David A. and Scott, E. M. and Southon, John and Turney, Chris and van der Plicht, J.",
    title = "Selection and Treatment of Data for Radiocarbon Calibration: An Update to the International Calibration (IntCal) Criteria",
    year = "2013",
    journal = "Radiocarbon",
    abstract = "High-quality data from appropriate archives are needed for the continuing improvement of radiocarbon calibration curves. We discuss here the basic assumptions behind 14 C dating that necessitate calibration and the relative strengths and weaknesses of archives from which calibration data are obtained. We also highlight the procedures, problems, and uncertainties involved in determining atmospheric and surface ocean 14 C/ 12 C in these archives, including a discussion of the various methods used to derive an independent absolute timescale and uncertainty. The types of data required for the current IntCal database and calibration curve model are tabulated with examples.",
    url = "https://doi.org/10.2458/azu\_js\_rc.55.16955",
    doi = "10.2458/azu\_js\_rc.55.16955",
    openalex = "W2135214253",
    references = "doi101006qres19960031, doi101016001670379290334f, doi101016jepsl201304006, doi101017s0033822200013904, doi101017s0033822200019123, doi101017s0033822200032999, doi101017s0033822200034202, doi101038345405a0, doi101038365143a0, doi101126science1226660, doi1011751520045019840230201otavoc20co2, doi102458azujsrc5516947"
}

We present a new record of radiocarbon ages measured by accelerator mass spectrometry (AMS) on a deep-sea core collected off the Pakistan Margin. The 14 C ages measured on the planktonic foraminifera Globigerinoides ruber from core MD04-2876 define a high and stable sedimentation rate on the order of 50 cm/kyr over the last 50 kyr. The site is distant from the main upwelling zone of the western Arabian Sea where 14 C reservoir age is large and may be variable. Many independent proxies based on elemental analyses, mineralogy, biomarkers, isotopic proxies, and foraminiferal abundances show abrupt changes correlative with Dansgaard-Oeschger and Heinrich events. It is now common knowledge that these climatic events also affected the Arabian Sea during the last glacial period through changes in the Indian monsoon and in ventilation at intermediate depths. The stratigraphic agreement between all proxies, from fine- to coarse-size fractions, indicates that the foraminiferal 14 C ages are representative of the different sediment fractions. To build a calendar age scale for core MD04-2876, we matched its climate record to the oxygen isotopic (δ 18 O) profile of Hulu Cave stalagmites that have been accurately dated by U-Th (Wang et al. 2001; Southon et al. 2012; Edwards et al., submitted). Both archives exhibit very similar signatures, even for century-long events linked to monsoonal variations. For comparison, we have also updated our previous work on core MD95-2042 from the Iberian Margin (Bard et al. 2004a,b,c), whose climate record has likewise been tuned to the high-resolution δ 18 O Hulu Cave profile. Sophisticated and novel statistical techniques were used to interpolate ages and calculate uncertainties between chronological tie-points (Heaton et al. 2013, this issue). The data from the Pakistan and Iberian margins compare well even if they come from distant sites characterized by different oceanic conditions. Collectively, the data also compare well with the IntCal09 curve, except for specific intervals around 16 cal kyr BP and from 28 to 31 cal kyr BP. During these intervals, the data indicate that 14 C is somewhat older than indicated by the IntCal09 curve. Agreement between the data from both oceanic sites suggests that the discrepancy is not due to local changes of sea-surface 14 C reservoir ages, but rather that the IntCal09 curve needed to be updated in these intervals as has been done in the framework of IntCal13 (Reimer et al. 2013a, this issue).

@article{doi102458azujsrc5517114,
    author = "Bard, Édouard and Ménot, Guillemette and Rostek, Frauke and Licari, Laëtitia and Böning, Philipp and Edwards, R. Lawrence and Cheng, Hai and Wang, Yongjin and Heaton, Timothy",
    title = "Radiocarbon Calibration/Comparison Records Based on Marine Sediments from the Pakistan and Iberian Margins",
    year = "2013",
    journal = "Radiocarbon",
    abstract = "We present a new record of radiocarbon ages measured by accelerator mass spectrometry (AMS) on a deep-sea core collected off the Pakistan Margin. The 14 C ages measured on the planktonic foraminifera Globigerinoides ruber from core MD04-2876 define a high and stable sedimentation rate on the order of 50 cm/kyr over the last 50 kyr. The site is distant from the main upwelling zone of the western Arabian Sea where 14 C reservoir age is large and may be variable. Many independent proxies based on elemental analyses, mineralogy, biomarkers, isotopic proxies, and foraminiferal abundances show abrupt changes correlative with Dansgaard-Oeschger and Heinrich events. It is now common knowledge that these climatic events also affected the Arabian Sea during the last glacial period through changes in the Indian monsoon and in ventilation at intermediate depths. The stratigraphic agreement between all proxies, from fine- to coarse-size fractions, indicates that the foraminiferal 14 C ages are representative of the different sediment fractions. To build a calendar age scale for core MD04-2876, we matched its climate record to the oxygen isotopic (δ 18 O) profile of Hulu Cave stalagmites that have been accurately dated by U-Th (Wang et al. 2001; Southon et al. 2012; Edwards et al., submitted). Both archives exhibit very similar signatures, even for century-long events linked to monsoonal variations. For comparison, we have also updated our previous work on core MD95-2042 from the Iberian Margin (Bard et al. 2004a,b,c), whose climate record has likewise been tuned to the high-resolution δ 18 O Hulu Cave profile. Sophisticated and novel statistical techniques were used to interpolate ages and calculate uncertainties between chronological tie-points (Heaton et al. 2013, this issue). The data from the Pakistan and Iberian margins compare well even if they come from distant sites characterized by different oceanic conditions. Collectively, the data also compare well with the IntCal09 curve, except for specific intervals around 16 cal kyr BP and from 28 to 31 cal kyr BP. During these intervals, the data indicate that 14 C is somewhat older than indicated by the IntCal09 curve. Agreement between the data from both oceanic sites suggests that the discrepancy is not due to local changes of sea-surface 14 C reservoir ages, but rather that the IntCal09 curve needed to be updated in these intervals as has been done in the framework of IntCal13 (Reimer et al. 2013a, this issue).",
    url = "https://doi.org/10.2458/azu\_js\_rc.55.17114",
    doi = "10.2458/azu\_js\_rc.55.17114",
    openalex = "W2158905005",
    references = "doi102458azujsrc5516955"
}

We present a compilation of tropospheric 14 CO 2 for the period 1950–2010, based on published radiocarbon data from selected records of atmospheric CO 2 sampling and tree-ring series. This compilation is a new version of the compilation by Hua and Barbetti (2004) and consists of yearly summer data sets for zonal, hemispheric, and global levels of atmospheric 14 C. In addition, compiled (and extended) monthly data sets for 5 atmospheric zones (3 in the Northern Hemisphere and 2 in the Southern Hemisphere) are reported. The annual data sets are for use in regional and global carbon model calculations, while the extended monthly data sets serve as calibration curves for 14 C dating of recent, short-lived terrestrial organic materials.

@article{doi102458azujsrcv55i216177,
    author = "Hua, Quan and Barbetti, Mike and Rakowski, Andrzej",
    title = "Atmospheric Radiocarbon for the Period 1950–2010",
    year = "2013",
    journal = "Radiocarbon",
    abstract = "We present a compilation of tropospheric 14 CO 2 for the period 1950–2010, based on published radiocarbon data from selected records of atmospheric CO 2 sampling and tree-ring series. This compilation is a new version of the compilation by Hua and Barbetti (2004) and consists of yearly summer data sets for zonal, hemispheric, and global levels of atmospheric 14 C. In addition, compiled (and extended) monthly data sets for 5 atmospheric zones (3 in the Northern Hemisphere and 2 in the Southern Hemisphere) are reported. The annual data sets are for use in regional and global carbon model calculations, while the extended monthly data sets serve as calibration curves for 14 C dating of recent, short-lived terrestrial organic materials.",
    url = "https://doi.org/10.2458/azu\_js\_rc.v55i2.16177",
    doi = "10.2458/azu\_js\_rc.v55i2.16177",
    openalex = "W2139388007",
    references = "doi101016jcell200504028, doi101017s0033822200003672, doi101017s0033822200019172, doi101017s0033822200033130, doi101017s0033822200033142, doi101017s0033822200033154, doi101017s0033822200053066, doi101038nature06902, doi101146annurevearth36031207124300, doi103402tellusav27i29900, openalexw1928750549"
}

Abstract. The responses of carbon dioxide (CO2) and other climate variables to an emission pulse of CO2 into the atmosphere are often used to compute the Global Warming Potential (GWP) and Global Temperature change Potential (GTP), to characterize the response timescales of Earth System models, and to build reduced-form models. In this carbon cycle-climate model intercomparison project, which spans the full model hierarchy, we quantify responses to emission pulses of different magnitudes injected under different conditions. The CO2 response shows the known rapid decline in the first few decades followed by a millennium-scale tail. For a 100 Gt-C emission pulse added to a constant CO2 concentration of 389 ppm, 25 ± 9% is still found in the atmosphere after 1000 yr; the ocean has absorbed 59 ± 12% and the land the remainder (16 ± 14%). The response in global mean surface air temperature is an increase by 0.20 ± 0.12 °C within the first twenty years; thereafter and until year 1000, temperature decreases only slightly, whereas ocean heat content and sea level continue to rise. Our best estimate for the Absolute Global Warming Potential, given by the time-integrated response in CO2 at year 100 multiplied by its radiative efficiency, is 92.5 × 10−15 yr W m−2 per kg-CO2. This value very likely (5 to 95% confidence) lies within the range of (68 to 117) × 10−15 yr W m−2 per kg-CO2. Estimates for time-integrated response in CO2 published in the IPCC First, Second, and Fourth Assessment and our multi-model best estimate all agree within 15% during the first 100 yr. The integrated CO2 response, normalized by the pulse size, is lower for pre-industrial conditions, compared to present day, and lower for smaller pulses than larger pulses. In contrast, the response in temperature, sea level and ocean heat content is less sensitive to these choices. Although, choices in pulse size, background concentration, and model lead to uncertainties, the most important and subjective choice to determine AGWP of CO2 and GWP is the time horizon.

@article{doi105194acp1327932013,
    author = "Joos, Fortunat and Roth, R. and Fuglestvedt, Jan S. and Peters, Glen P. and Enting, I. G. and von Bloh, Werner and Brovkin, Victor and Burke, Eleanor and Eby, Michael and Edwards, Neil R. and Friedrich, Tobias and Frölicher, Thomas L. and Halloran, Paul R. and Holden, Philip B. and Jones, Chris and Kleinen, Thomas and Mackenzie, Fred T. and Matsumoto, Katsumi and Meinshausen, Malte and Plattner, Gian‐Kasper and Reisinger, Andy and Segschneider, Joachim and Shaffer, Gary and Steinacher, M. and Strassmann, Kuno and Tanaka, Katsumasa and Timmermann, Axel and Weaver, Andrew J.",
    title = "Carbon dioxide and climate impulse response functions for the computation of greenhouse gas metrics: a multi-model analysis",
    year = "2013",
    journal = "Atmospheric chemistry and physics",
    abstract = "Abstract. The responses of carbon dioxide (CO2) and other climate variables to an emission pulse of CO2 into the atmosphere are often used to compute the Global Warming Potential (GWP) and Global Temperature change Potential (GTP), to characterize the response timescales of Earth System models, and to build reduced-form models. In this carbon cycle-climate model intercomparison project, which spans the full model hierarchy, we quantify responses to emission pulses of different magnitudes injected under different conditions. The CO2 response shows the known rapid decline in the first few decades followed by a millennium-scale tail. For a 100 Gt-C emission pulse added to a constant CO2 concentration of 389 ppm, 25 ± 9\% is still found in the atmosphere after 1000 yr; the ocean has absorbed 59 ± 12\% and the land the remainder (16 ± 14\%). The response in global mean surface air temperature is an increase by 0.20 ± 0.12 °C within the first twenty years; thereafter and until year 1000, temperature decreases only slightly, whereas ocean heat content and sea level continue to rise. Our best estimate for the Absolute Global Warming Potential, given by the time-integrated response in CO2 at year 100 multiplied by its radiative efficiency, is 92.5 × 10−15 yr W m−2 per kg-CO2. This value very likely (5 to 95\% confidence) lies within the range of (68 to 117) × 10−15 yr W m−2 per kg-CO2. Estimates for time-integrated response in CO2 published in the IPCC First, Second, and Fourth Assessment and our multi-model best estimate all agree within 15\% during the first 100 yr. The integrated CO2 response, normalized by the pulse size, is lower for pre-industrial conditions, compared to present day, and lower for smaller pulses than larger pulses. In contrast, the response in temperature, sea level and ocean heat content is less sensitive to these choices. Although, choices in pulse size, background concentration, and model lead to uncertainties, the most important and subjective choice to determine AGWP of CO2 and GWP is the time horizon.",
    url = "https://doi.org/10.5194/acp-13-2793-2013",
    doi = "10.5194/acp-13-2793-2013",
    openalex = "W2023168822",
    references = "doi101111j215334901975tb01671x, doi105194gmd45432011"
}

Abstract. High-latitude terrestrial ecosystems are key components in the global carbon cycle. The Northern Circumpolar Soil Carbon Database (NCSCD) was developed to quantify stocks of soil organic carbon (SOC) in the northern circumpolar permafrost region (a total area of 18.7 × 106 km2). The NCSCD is a geographical information system (GIS) data set that has been constructed using harmonized regional soil classification maps together with pedon data from the northern permafrost region. Previously, the NCSCD has been used to calculate SOC storage to the reference depths 0–30 cm and 0–100 cm (based on 1778 pedons). It has been shown that soils of the northern circumpolar permafrost region also contain significant quantities of SOC in the 100–300 cm depth range, but there has been no circumpolar compilation of pedon data to quantify this deeper SOC pool and there are no spatially distributed estimates of SOC storage below 100 cm depth in this region. Here we describe the synthesis of an updated pedon data set for SOC storage (kg C m−2) in deep soils of the northern circumpolar permafrost regions, with separate data sets for the 100–200 cm (524 pedons) and 200–300 cm (356 pedons) depth ranges. These pedons have been grouped into the North American and Eurasian sectors and the mean SOC storage for different soil taxa (subdivided into Gelisols including the sub-orders Histels, Turbels, Orthels, permafrost-free Histosols, and permafrost-free mineral soil orders) has been added to the updated NCSCDv2. The updated version of the data set is freely available online in different file formats and spatial resolutions that enable spatially explicit applications in GIS mapping and terrestrial ecosystem models. While this newly compiled data set adds to our knowledge of SOC in the 100–300 cm depth range, it also reveals that large uncertainties remain. Identified data gaps include spatial coverage of deep (> 100 cm) pedons in many regions as well as the spatial extent of areas with thin soils overlying bedrock and the quantity and distribution of massive ground ice. An open access data-portal for the pedon data set and the GIS-data sets is available online at http://bolin.su.se/data/ncscd/. The NCSCDv2 data set has a digital object identifier (doi:10.5879/ECDS/00000002).

@article{doi105194essd53932013,
    author = "Hugelius, Gustaf and Bockheim, J. G. and Camill, Philip and Elberling, Bo and Grosse, Guido and Harden, J. W. and Johnson, K. and Jorgenson, T. and Koven, Charles D. and Kuhry, Peter and Michaelson, G. J. and Mishra, Umakant and Palmtag, Juri and Ping, Chien‐Lu and O’Donnell, Jonathan A. and Schirrmeister, Lutz and Schuur, Edward A. G. and Sheng, Yongwei and Smith, L. C. and Strauß, Jens and Yu, Zicheng",
    title = "A new data set for estimating organic carbon storage to 3 m depth in soils of the northern circumpolar permafrost region",
    year = "2013",
    journal = "Earth system science data",
    abstract = "Abstract. High-latitude terrestrial ecosystems are key components in the global carbon cycle. The Northern Circumpolar Soil Carbon Database (NCSCD) was developed to quantify stocks of soil organic carbon (SOC) in the northern circumpolar permafrost region (a total area of 18.7 × 106 km2). The NCSCD is a geographical information system (GIS) data set that has been constructed using harmonized regional soil classification maps together with pedon data from the northern permafrost region. Previously, the NCSCD has been used to calculate SOC storage to the reference depths 0–30 cm and 0–100 cm (based on 1778 pedons). It has been shown that soils of the northern circumpolar permafrost region also contain significant quantities of SOC in the 100–300 cm depth range, but there has been no circumpolar compilation of pedon data to quantify this deeper SOC pool and there are no spatially distributed estimates of SOC storage below 100 cm depth in this region. Here we describe the synthesis of an updated pedon data set for SOC storage (kg C m−2) in deep soils of the northern circumpolar permafrost regions, with separate data sets for the 100–200 cm (524 pedons) and 200–300 cm (356 pedons) depth ranges. These pedons have been grouped into the North American and Eurasian sectors and the mean SOC storage for different soil taxa (subdivided into Gelisols including the sub-orders Histels, Turbels, Orthels, permafrost-free Histosols, and permafrost-free mineral soil orders) has been added to the updated NCSCDv2. The updated version of the data set is freely available online in different file formats and spatial resolutions that enable spatially explicit applications in GIS mapping and terrestrial ecosystem models. While this newly compiled data set adds to our knowledge of SOC in the 100–300 cm depth range, it also reveals that large uncertainties remain. Identified data gaps include spatial coverage of deep (> 100 cm) pedons in many regions as well as the spatial extent of areas with thin soils overlying bedrock and the quantity and distribution of massive ground ice. An open access data-portal for the pedon data set and the GIS-data sets is available online at http://bolin.su.se/data/ncscd/. The NCSCDv2 data set has a digital object identifier (doi:10.5879/ECDS/00000002).",
    url = "https://doi.org/10.5194/essd-5-393-2013",
    doi = "10.5194/essd-5-393-2013",
    openalex = "W2111939765",
    references = "doi101016s0277379103001677"
}

@incollection{crossref2014carbon,
    title = "carbon 14",
    year = "2014",
    booktitle = "Dictionary Geotechnical Engineering/Wörterbuch GeoTechnik",
    url = "https://doi.org/10.1007/978-3-642-41714-6\_30489",
    doi = "10.1007/978-3-642-41714-6\_30489",
    pages = "192-192"
}

Abstract The export of organic carbon from the surface ocean by sinking particles is an important, yet highly uncertain, component of the global carbon cycle. Here we introduce a mechanistic assessment of the global ocean carbon export using satellite observations, including determinations of net primary production and the slope of the particle size spectrum, to drive a food‐web model that estimates the production of sinking zooplankton feces and algal aggregates comprising the sinking particle flux at the base of the euphotic zone. The synthesis of observations and models reveals fundamentally different and ecologically consistent regional‐scale patterns in export and export efficiency not found in previous global carbon export assessments. The model reproduces regional‐scale particle export field observations and predicts a climatological mean global carbon export from the euphotic zone of ~6 Pg C yr −1. Global export estimates show small variation (typically < 10%) to factor of 2 changes in model parameter values. The model is also robust to the choices of the satellite data products used and enables interannual changes to be quantified. The present synthesis of observations and models provides a path for quantifying the ocean's biological pump.

@article{doi1010022013gb004743,
    author = "Siegel, David A. and Buesseler, Ken O. and Doney, Scott C. and Sailley, Sévrine and Behrenfeld, Michael J. and Boyd, Philip W.",
    title = "Global assessment of ocean carbon export by combining satellite observations and food‐web models",
    year = "2014",
    journal = "Global Biogeochemical Cycles",
    abstract = "Abstract The export of organic carbon from the surface ocean by sinking particles is an important, yet highly uncertain, component of the global carbon cycle. Here we introduce a mechanistic assessment of the global ocean carbon export using satellite observations, including determinations of net primary production and the slope of the particle size spectrum, to drive a food‐web model that estimates the production of sinking zooplankton feces and algal aggregates comprising the sinking particle flux at the base of the euphotic zone. The synthesis of observations and models reveals fundamentally different and ecologically consistent regional‐scale patterns in export and export efficiency not found in previous global carbon export assessments. The model reproduces regional‐scale particle export field observations and predicts a climatological mean global carbon export from the euphotic zone of \textasciitilde 6 Pg C yr −1. Global export estimates show small variation (typically < 10\%) to factor of 2 changes in model parameter values. The model is also robust to the choices of the satellite data products used and enables interannual changes to be quantified. The present synthesis of observations and models provides a path for quantifying the ocean's biological pump.",
    url = "https://doi.org/10.1002/2013gb004743",
    doi = "10.1002/2013gb004743",
    openalex = "W2143167281",
    references = "doi104319lo20095441210"
}

Radiocarbon analysis of organic materials, with the comparison of values with those of the post-1950 modern bomb curve, has proven useful in forensic science to help evaluate the antiquity of evidence. Applications are particularly helpful in the study of human remains, especially with those displaying advanced decomposition of soft tissues. Radiocarbon analysis can reveal if the remains relate to the modern, post-1950 era and if so, also provide information needed to evaluate the death and birth date. Sample selection and interpretation of results must be guided by knowledge of the formation and remodeling of different human tissues, as well as contextual information and the approximate age at death of the individual represented. Dental enamel does not remodel and thus captures dietary radiocarbon values at the time of juvenile formation. Most other human tissues do remodel but at differing rates and therefore collectively offer key information relative to the estimation of the death date.

@article{doi1011111556402912535,
    author = "Ubelaker, Douglas H.",
    title = "Radiocarbon Analysis of Human Remains: A Review of Forensic Applications",
    year = "2014",
    journal = "Journal of Forensic Sciences",
    abstract = "Radiocarbon analysis of organic materials, with the comparison of values with those of the post-1950 modern bomb curve, has proven useful in forensic science to help evaluate the antiquity of evidence. Applications are particularly helpful in the study of human remains, especially with those displaying advanced decomposition of soft tissues. Radiocarbon analysis can reveal if the remains relate to the modern, post-1950 era and if so, also provide information needed to evaluate the death and birth date. Sample selection and interpretation of results must be guided by knowledge of the formation and remodeling of different human tissues, as well as contextual information and the approximate age at death of the individual represented. Dental enamel does not remodel and thus captures dietary radiocarbon values at the time of juvenile formation. Most other human tissues do remodel but at differing rates and therefore collectively offer key information relative to the estimation of the death date.",
    url = "https://doi.org/10.1111/1556-4029.12535",
    doi = "10.1111/1556-4029.12535",
    openalex = "W2028041659"
}

Here, we present results from the most comprehensive compilation of Holocene peat soil properties with associated carbon and nitrogen accumulation rates for northern peatlands. Our database consists of 268 peat cores from 215 sites located north of 45°N. It encompasses regions within which peat carbon data have only recently become available, such as the West Siberia Lowlands, the Hudson Bay Lowlands, Kamchatka in Far East Russia, and the Tibetan Plateau. For all northern peatlands, carbon content in organic matter was estimated at 42 ± 3% (standard deviation) for Sphagnum peat, 51 ± 2% for non- Sphagnum peat, and at 49 ± 2% overall. Dry bulk density averaged 0.12 ± 0.07 g/cm 3, organic matter bulk density averaged 0.11 ± 0.05 g/cm 3, and total carbon content in peat averaged 47 ± 6%. In general, large differences were found between Sphagnum and non- Sphagnum peat types in terms of peat properties. Time-weighted peat carbon accumulation rates averaged 23 ± 2 (standard error of mean) g C/m 2 /yr during the Holocene on the basis of 151 peat cores from 127 sites, with the highest rates of carbon accumulation (25–28 g C/m 2 /yr) recorded during the early Holocene when the climate was warmer than the present. Furthermore, we estimate the northern peatland carbon and nitrogen pools at 436 and 10 gigatons, respectively. The database is publicly available at https://peatlands.lehigh.edu.

@article{doi1011770959683614538073,
    author = "Loisel, Julie and Yu, Zicheng and Beilman, David W. and Camill, Philip and Alm, Jukka and Amesbury, Matthew J. and Anderson, David E. and Andersson, Sofia and Bochicchio, Christopher and Barber, Keith and Belyea, Lisa R. and Bunbury, Joan and Chambers, Frank M. and Charman, Dan J. and Vleeschouwer, François De and Fiałkiewicz-Kozieł, Barbara and Finkelstein, Sarah A. and Gałka, Mariusz and Garneau, Michelle and Hammarlund, Dan and Hinchcliffe, William and Holmquist, James R. and Hughes, Paul and Jones, Miriam C. and Klein, Eric S. and Kokfelt, Ulla and Korhola, Atte and Kuhry, Peter and Lamarre, Alexandre and Lamentowicz, Mariusz and Large, David J. and Lavoie, Martin and MacDonald, Glen M. and Magnan, Gabriel and Mäkilä, M. and Mallon, Gunnar and Mathijssen, Paul and Mauquoy, Dmitri and McCarroll, Julia and Moore, Tim R. and Nichols, J. E. and O'Reilly, B. and Oksanen, Pirita and Packalen, Maara and Peteet, D. M. and Richard, Pierre J. H. and Robinson, Stephen D. and Ronkainen, Tiina and Rundgren, Mats and Sannel, A. Britta K. and Tarnocai, C. and Thom, Tim and Tuittila, Eeva‐Stiina and Turetsky, Merritt R. and Väliranta, Minna and van der Linden, M. and van Geel, B. and van Bellen, Simon and Vitt, Dale H. and Zhao, Yan and Zhou, Weijian",
    title = "A database and synthesis of northern peatland soil properties and Holocene carbon and nitrogen accumulation",
    year = "2014",
    journal = "The Holocene",
    abstract = "Here, we present results from the most comprehensive compilation of Holocene peat soil properties with associated carbon and nitrogen accumulation rates for northern peatlands. Our database consists of 268 peat cores from 215 sites located north of 45°N. It encompasses regions within which peat carbon data have only recently become available, such as the West Siberia Lowlands, the Hudson Bay Lowlands, Kamchatka in Far East Russia, and the Tibetan Plateau. For all northern peatlands, carbon content in organic matter was estimated at 42 ± 3\% (standard deviation) for Sphagnum peat, 51 ± 2\% for non- Sphagnum peat, and at 49 ± 2\% overall. Dry bulk density averaged 0.12 ± 0.07 g/cm 3, organic matter bulk density averaged 0.11 ± 0.05 g/cm 3, and total carbon content in peat averaged 47 ± 6\%. In general, large differences were found between Sphagnum and non- Sphagnum peat types in terms of peat properties. Time-weighted peat carbon accumulation rates averaged 23 ± 2 (standard error of mean) g C/m 2 /yr during the Holocene on the basis of 151 peat cores from 127 sites, with the highest rates of carbon accumulation (25–28 g C/m 2 /yr) recorded during the early Holocene when the climate was warmer than the present. Furthermore, we estimate the northern peatland carbon and nitrogen pools at 436 and 10 gigatons, respectively. The database is publicly available at https://peatlands.lehigh.edu.",
    url = "https://doi.org/10.1177/0959683614538073",
    doi = "10.1177/0959683614538073",
    openalex = "W2152976421",
    references = "doi1018900820251"
}

Abstract The role played by river networks in regional and global carbon (C) budgets is receiving increasing attention. Despite the potential of radiocarbon measurements (Δ 14 C) to elucidate sources and cycling of different riverine C pools, there remain large regions for which no data are available and no comprehensive attempts to synthesize the available information and examine global patterns in the 14 C content of different riverine C pools. Here we present new 14 C data on particulate and dissolved organic C (POC and DOC) from six river basins in tropical and subtropical Africa and compiled >1400 literature Δ 14 C data and ancillary parameters from rivers globally. Our analysis reveals a consistent pattern whereby POC is progressively older in systems carrying higher sediment loads, coinciding with a lower organic carbon content. At the global scale, this pattern leads to a proposed global median Δ 14 C signature of −203‰, corresponding to an age of ~1800 years B.P. For DOC exported to the coastal zone, we predict a modern (decadal) age (Δ 14 C = +22 to +46‰), and paired data sets confirm that riverine DOC is generally more recent in origin than POC—in contrast to the situation in ocean environments. Weathering regimes complicate the interpretation of 14 C ages of dissolved inorganic carbon, but the available data favor the hypothesis that in most cases, more recent organic C is preferentially mineralized.

@article{doi1010022014gb004911,
    author = "Marwick, Trent R. and Tamooh, F. and Teodoru, Cristian R. and Borges, Alberto and Darchambeau, François and Bouillon, Steven",
    title = "The age of river‐transported carbon: A global perspective",
    year = "2015",
    journal = "Global Biogeochemical Cycles",
    abstract = "Abstract The role played by river networks in regional and global carbon (C) budgets is receiving increasing attention. Despite the potential of radiocarbon measurements (Δ 14 C) to elucidate sources and cycling of different riverine C pools, there remain large regions for which no data are available and no comprehensive attempts to synthesize the available information and examine global patterns in the 14 C content of different riverine C pools. Here we present new 14 C data on particulate and dissolved organic C (POC and DOC) from six river basins in tropical and subtropical Africa and compiled >1400 literature Δ 14 C data and ancillary parameters from rivers globally. Our analysis reveals a consistent pattern whereby POC is progressively older in systems carrying higher sediment loads, coinciding with a lower organic carbon content. At the global scale, this pattern leads to a proposed global median Δ 14 C signature of −203‰, corresponding to an age of \textasciitilde 1800 years B.P. For DOC exported to the coastal zone, we predict a modern (decadal) age (Δ 14 C = +22 to +46‰), and paired data sets confirm that riverine DOC is generally more recent in origin than POC—in contrast to the situation in ocean environments. Weathering regimes complicate the interpretation of 14 C ages of dissolved inorganic carbon, but the available data favor the hypothesis that in most cases, more recent organic C is preferentially mineralized.",
    url = "https://doi.org/10.1002/2014gb004911",
    doi = "10.1002/2014gb004911",
    openalex = "W1545725870",
    references = "doi1010292004gl019512, doi101073pnas1004933107"
}

The response of soil carbon dynamics to climate and land-use change will affect both the future climate and the quality of ecosystems. Deep soil carbon (>20 cm) is the primary component of the soil carbon pool, but the dynamics of deep soil carbon remain poorly understood. Therefore, radiocarbon activity (Δ14C), which is a function of the age of carbon, may help to understand the rates of soil carbon biodegradation and stabilization. We analyzed the published 14C contents in 122 profiles of mineral soil that were well distributed in most of the large world biomes, except for the boreal zone. With a multivariate extension of a linear mixed-effects model whose inference was based on the parallel combination of two algorithms, the expectation-maximization (EM) and the Metropolis-Hasting algorithms, we expressed soil Δ14C profiles as a four-parameter function of depth. The four-parameter model produced insightful predictions of soil Δ14C as dependent on depth, soil type, climate, vegetation, land-use and date of sampling (R2=0.68). Further analysis with the model showed that the age of topsoil carbon was primarily affected by climate and cultivation. By contrast, the age of deep soil carbon was affected more by soil taxa than by climate and thus illustrated the strong dependence of soil carbon dynamics on other pedologic traits such as clay content and mineralogy.

@article{doi101111gcb13012,
    author = "Mathieu, Jordane A. and Hatté, Christine and Balesdent, Jérôme and Parent, Éric",
    title = "Deep soil carbon dynamics are driven more by soil type than by climate: a worldwide meta‐analysis of radiocarbon profiles",
    year = "2015",
    journal = "Global Change Biology",
    abstract = "The response of soil carbon dynamics to climate and land-use change will affect both the future climate and the quality of ecosystems. Deep soil carbon (>20 cm) is the primary component of the soil carbon pool, but the dynamics of deep soil carbon remain poorly understood. Therefore, radiocarbon activity (Δ14C), which is a function of the age of carbon, may help to understand the rates of soil carbon biodegradation and stabilization. We analyzed the published 14C contents in 122 profiles of mineral soil that were well distributed in most of the large world biomes, except for the boreal zone. With a multivariate extension of a linear mixed-effects model whose inference was based on the parallel combination of two algorithms, the expectation-maximization (EM) and the Metropolis-Hasting algorithms, we expressed soil Δ14C profiles as a four-parameter function of depth. The four-parameter model produced insightful predictions of soil Δ14C as dependent on depth, soil type, climate, vegetation, land-use and date of sampling (R2=0.68). Further analysis with the model showed that the age of topsoil carbon was primarily affected by climate and cultivation. By contrast, the age of deep soil carbon was affected more by soil taxa than by climate and thus illustrated the strong dependence of soil carbon dynamics on other pedologic traits such as clay content and mineralogy.",
    url = "https://doi.org/10.1111/gcb.13012",
    doi = "10.1111/gcb.13012",
    openalex = "W2157412927",
    references = "doi102458azujsrc5516955, doi102458azujsrcv55i216177"
}

The impacts of climate extremes on terrestrial ecosystems are poorly understood but important for predicting carbon cycle feedbacks to climate change. Coupled climate-carbon cycle models typically assume that vegetation recovery from extreme drought is immediate and complete, which conflicts with the understanding of basic plant physiology. We examined the recovery of stem growth in trees after severe drought at 1338 forest sites across the globe, comprising 49,339 site-years, and compared the results with simulated recovery in climate-vegetation models. We found pervasive and substantial "legacy effects" of reduced growth and incomplete recovery for 1 to 4 years after severe drought. Legacy effects were most prevalent in dry ecosystems, among Pinaceae, and among species with low hydraulic safety margins. In contrast, limited or no legacy effects after drought were simulated by current climate-vegetation models. Our results highlight hysteresis in ecosystem-level carbon cycling and delayed recovery from climate extremes.

@article{doi101126scienceaab1833,
    author = "Anderegg, William R. L. and Schwalm, Christopher R. and Biondi, Franco and Camarero, J. Julio and Koch, George W. and Litvak, M. E. and Ogle, Kiona and Shaw, John D. and Shevliakova, Elena and Williams, Park and Wolf, Adam and Ziaco, Emanuele and Pacala, Stephen W.",
    title = "Pervasive drought legacies in forest ecosystems and their implications for carbon cycle models",
    year = "2015",
    journal = "Science",
    abstract = {The impacts of climate extremes on terrestrial ecosystems are poorly understood but important for predicting carbon cycle feedbacks to climate change. Coupled climate-carbon cycle models typically assume that vegetation recovery from extreme drought is immediate and complete, which conflicts with the understanding of basic plant physiology. We examined the recovery of stem growth in trees after severe drought at 1338 forest sites across the globe, comprising 49,339 site-years, and compared the results with simulated recovery in climate-vegetation models. We found pervasive and substantial "legacy effects" of reduced growth and incomplete recovery for 1 to 4 years after severe drought. Legacy effects were most prevalent in dry ecosystems, among Pinaceae, and among species with low hydraulic safety margins. In contrast, limited or no legacy effects after drought were simulated by current climate-vegetation models. Our results highlight hysteresis in ecosystem-level carbon cycling and delayed recovery from climate extremes.},
    url = "https://doi.org/10.1126/science.aab1833",
    doi = "10.1126/science.aab1833",
    openalex = "W1913444490",
    references = "doi1010292011jd016048, doi101038nature14283, doi1018960seitai14397"
}

Abstract. The land and ocean absorb on average just over half of the anthropogenic emissions of carbon dioxide (CO2) every year. These CO2 "sinks" are modulated by climate change and variability. Here we use a suite of nine dynamic global vegetation models (DGVMs) and four ocean biogeochemical general circulation models (OBGCMs) to estimate trends driven by global and regional climate and atmospheric CO2 in land and oceanic CO2 exchanges with the atmosphere over the period 1990–2009, to attribute these trends to underlying processes in the models, and to quantify the uncertainty and level of inter-model agreement. The models were forced with reconstructed climate fields and observed global atmospheric CO2; land use and land cover changes are not included for the DGVMs. Over the period 1990–2009, the DGVMs simulate a mean global land carbon sink of −2.4 ± 0.7 Pg C yr−1 with a small significant trend of −0.06 ± 0.03 Pg C yr−2 (increasing sink). Over the more limited period 1990–2004, the ocean models simulate a mean ocean sink of −2.2 ± 0.2 Pg C yr−1 with a trend in the net C uptake that is indistinguishable from zero (−0.01 ± 0.02 Pg C yr−2). The two ocean models that extended the simulations until 2009 suggest a slightly stronger, but still small, trend of −0.02 ± 0.01 Pg C yr−2. Trends from land and ocean models compare favourably to the land greenness trends from remote sensing, atmospheric inversion results, and the residual land sink required to close the global carbon budget. Trends in the land sink are driven by increasing net primary production (NPP), whose statistically significant trend of 0.22 ± 0.08 Pg C yr−2 exceeds a significant trend in heterotrophic respiration of 0.16 ± 0.05 Pg C yr−2 – primarily as a consequence of widespread CO2 fertilisation of plant production. Most of the land-based trend in simulated net carbon uptake originates from natural ecosystems in the tropics (−0.04 ± 0.01 Pg C yr−2), with almost no trend over the northern land region, where recent warming and reduced rainfall offsets the positive impact of elevated atmospheric CO2 and changes in growing season length on carbon storage. The small uptake trend in the ocean models emerges because climate variability and change, and in particular increasing sea surface temperatures, tend to counter\\-act the trend in ocean uptake driven by the increase in atmospheric CO2. Large uncertainty remains in the magnitude and sign of modelled carbon trends in several regions, as well as regarding the influence of land use and land cover changes on regional trends.

@article{doi105194bg126532015,
    author = "Sitch, Stephen and Friedlingstein, Pierre and Gruber, Nicolas and Jones, S. D. M. and Murray‐Tortarolo, Guillermo N. and Ahlström, Anders and Doney, Scott C. and Graven, Heather and Heinze, Christoph and Huntingford, Chris and Levis, Samuel and Levy, Peter and Lomas, M. and Poulter, Benjamin and Viovy, Nicolas and Zaehle, Sönke and Zeng, Ning and Arneth, Almut and Bonan, Gordon B. and Bopp, Laurent and Canadell, Josep G. and Chevallier, Frédéric and Ciais, Philippe and Ellis, Rich and Gloor, Manuel and Peylin, Philippe and Piao, Shilong and Quéré, Corinne Le and Smith, Benjamin and Zhu, Zaichun and Myneni, Ranga B.",
    title = "Recent trends and drivers of regional sources and sinks of carbon dioxide",
    year = "2015",
    journal = "Biogeosciences",
    abstract = {Abstract. The land and ocean absorb on average just over half of the anthropogenic emissions of carbon dioxide (CO2) every year. These CO2 "sinks" are modulated by climate change and variability. Here we use a suite of nine dynamic global vegetation models (DGVMs) and four ocean biogeochemical general circulation models (OBGCMs) to estimate trends driven by global and regional climate and atmospheric CO2 in land and oceanic CO2 exchanges with the atmosphere over the period 1990–2009, to attribute these trends to underlying processes in the models, and to quantify the uncertainty and level of inter-model agreement. The models were forced with reconstructed climate fields and observed global atmospheric CO2; land use and land cover changes are not included for the DGVMs. Over the period 1990–2009, the DGVMs simulate a mean global land carbon sink of −2.4 ± 0.7 Pg C yr−1 with a small significant trend of −0.06 ± 0.03 Pg C yr−2 (increasing sink). Over the more limited period 1990–2004, the ocean models simulate a mean ocean sink of −2.2 ± 0.2 Pg C yr−1 with a trend in the net C uptake that is indistinguishable from zero (−0.01 ± 0.02 Pg C yr−2). The two ocean models that extended the simulations until 2009 suggest a slightly stronger, but still small, trend of −0.02 ± 0.01 Pg C yr−2. Trends from land and ocean models compare favourably to the land greenness trends from remote sensing, atmospheric inversion results, and the residual land sink required to close the global carbon budget. Trends in the land sink are driven by increasing net primary production (NPP), whose statistically significant trend of 0.22 ± 0.08 Pg C yr−2 exceeds a significant trend in heterotrophic respiration of 0.16 ± 0.05 Pg C yr−2 – primarily as a consequence of widespread CO2 fertilisation of plant production. Most of the land-based trend in simulated net carbon uptake originates from natural ecosystems in the tropics (−0.04 ± 0.01 Pg C yr−2), with almost no trend over the northern land region, where recent warming and reduced rainfall offsets the positive impact of elevated atmospheric CO2 and changes in growing season length on carbon storage. The small uptake trend in the ocean models emerges because climate variability and change, and in particular increasing sea surface temperatures, tend to counter\\-act the trend in ocean uptake driven by the increase in atmospheric CO2. Large uncertainty remains in the magnitude and sign of modelled carbon trends in several regions, as well as regarding the influence of land use and land cover changes on regional trends.},
    url = "https://doi.org/10.5194/bg-12-653-2015",
    doi = "10.5194/bg-12-653-2015",
    openalex = "W2035962295",
    references = "doi1010292006gb002784, doi105194bg1066992013"
}

Abstract. Accurate assessment of anthropogenic carbon dioxide (CO2) emissions and their redistribution among the atmosphere, ocean, and terrestrial biosphere is important to better understand the global carbon cycle, support the development of climate policies, and project future climate change. Here we describe data sets and a methodology to quantify all major components of the global carbon budget, including their uncertainties, based on the combination of a range of data, algorithms, statistics, and model estimates and their interpretation by a broad scientific community. We discuss changes compared to previous estimates as well as consistency within and among components, alongside methodology and data limitations. CO2 emissions from fossil fuels and industry (EFF) are based on energy statistics and cement production data, while emissions from land-use change (ELUC), mainly deforestation, are based on combined evidence from land-cover-change data, fire activity associated with deforestation, and models. The global atmospheric CO2 concentration is measured directly and its rate of growth (GATM) is computed from the annual changes in concentration. The mean ocean CO2 sink (SOCEAN) is based on observations from the 1990s, while the annual anomalies and trends are estimated with ocean models. The variability in SOCEAN is evaluated with data products based on surveys of ocean CO2 measurements. The global residual terrestrial CO2 sink (SLAND) is estimated by the difference of the other terms of the global carbon budget and compared to results of independent dynamic global vegetation models forced by observed climate, CO2, and land-cover change (some including nitrogen–carbon interactions). We compare the mean land and ocean fluxes and their variability to estimates from three atmospheric inverse methods for three broad latitude bands. All uncertainties are reported as ±1σ, reflecting the current capacity to characterise the annual estimates of each component of the global carbon budget. For the last decade available (2005–2014), EFF was 9.0 ± 0.5 GtC yr−1, ELUC was 0.9 ± 0.5 GtC yr−1, GATM was 4.4 ± 0.1 GtC yr−1, SOCEAN was 2.6 ± 0.5 GtC yr−1, and SLAND was 3.0 ± 0.8 GtC yr−1. For the year 2014 alone, EFF grew to 9.8 ± 0.5 GtC yr−1, 0.6 % above 2013, continuing the growth trend in these emissions, albeit at a slower rate compared to the average growth of 2.2 % yr−1 that took place during 2005–2014. Also, for 2014, ELUC was 1.1 ± 0.5 GtC yr−1, GATM was 3.9 ± 0.2 GtC yr−1, SOCEAN was 2.9 ± 0.5 GtC yr−1, and SLAND was 4.1 ± 0.9 GtC yr−1. GATM was lower in 2014 compared to the past decade (2005–2014), reflecting a larger SLAND for that year. The global atmospheric CO2 concentration reached 397.15 ± 0.10 ppm averaged over 2014. For 2015, preliminary data indicate that the growth in EFF will be near or slightly below zero, with a projection of −0.6 [range of −1.6 to +0.5] %, based on national emissions projections for China and the USA, and projections of gross domestic product corrected for recent changes in the carbon intensity of the global economy for the rest of the world. From this projection of EFF and assumed constant ELUC for 2015, cumulative emissions of CO2 will reach about 555 ± 55 GtC (2035 ± 205 GtCO2) for 1870–2015, about 75 % from EFF and 25 % from ELUC. This living data update documents changes in the methods and data sets used in this new carbon budget compared with previous publications of this data set (Le Quéré et al., 2015, 2014, 2013). All observations presented here can be downloaded from the Carbon Dioxide Information Analysis Center (doi:10.3334/CDIAC/GCP_2015).

@article{doi105194essd73492015,
    author = "Quéré, Corinne Le and Moriarty, R. and Andrew, Robbie M. and Canadell, Josep G. and Sitch, Stephen and Korsbakken, Jan Ivar and Friedlingstein, Pierre and Peters, Glen P. and Andres, R. J. and Boden, T. A. and Houghton, R. A. and House, Joanna I. and Keeling, Ralph F. and Tans, Pieter P. and Arneth, Almut and Bakker, Dorothée C. E. and Barbero, Leticia and Bopp, Laurent and Chang, Jinfeng and Chevallier, Frédéric and Chini, Louise and Ciais, Philippe and Fader, Marianela and Feely, Richard A. and Gkritzalis, Thanos and Harris, Ian and Hauck, Judith and Ilyina, Tatiana and Jain, Atul K. and Kato, Etsushi and Kitidis, Vassilis and Goldewijk, Kees Klein and Koven, Charles D. and Landschützer, Peter and Lauvset, Siv K. and Lefèvre, Nathalie and Lenton, Andrew and Lima, Ivan D. and Metzl, Nicolas and Millero, Frank J. and Munro, David R. and Murata, Akihiko and Nabel, Julia E. M. S. and Nakaoka, Shin‐Ichiro and Nojiri, Yukihiro and O’Brien, Kevin and Olsen, Are and Ono, Tsuneo and Pérez, Fı́z F. and Pfeil, Benjamin and Pierrot, Denis and Poulter, Benjamin and Rehder, Gregor and Rödenbeck, Christian and Saito, Shu and Schuster, Ute and Schwinger, Jörg and Séférian, Roland and Steinhoff, Tobias and Stocker, Benjamin D. and Sutton, Adrienne J. and Takahashi, Taro and Tilbrook, Bronte and Luijkx, Ingrid T. and van der Werf, Guido R. and van Heuven, Steven and Vandemark, Doug and Viovy, Nicolas and Wiltshire, A. and Zaehle, Sönke and Zeng, Ning",
    title = "Global Carbon Budget 2015",
    year = "2015",
    journal = "Earth system science data",
    abstract = "Abstract. Accurate assessment of anthropogenic carbon dioxide (CO2) emissions and their redistribution among the atmosphere, ocean, and terrestrial biosphere is important to better understand the global carbon cycle, support the development of climate policies, and project future climate change. Here we describe data sets and a methodology to quantify all major components of the global carbon budget, including their uncertainties, based on the combination of a range of data, algorithms, statistics, and model estimates and their interpretation by a broad scientific community. We discuss changes compared to previous estimates as well as consistency within and among components, alongside methodology and data limitations. CO2 emissions from fossil fuels and industry (EFF) are based on energy statistics and cement production data, while emissions from land-use change (ELUC), mainly deforestation, are based on combined evidence from land-cover-change data, fire activity associated with deforestation, and models. The global atmospheric CO2 concentration is measured directly and its rate of growth (GATM) is computed from the annual changes in concentration. The mean ocean CO2 sink (SOCEAN) is based on observations from the 1990s, while the annual anomalies and trends are estimated with ocean models. The variability in SOCEAN is evaluated with data products based on surveys of ocean CO2 measurements. The global residual terrestrial CO2 sink (SLAND) is estimated by the difference of the other terms of the global carbon budget and compared to results of independent dynamic global vegetation models forced by observed climate, CO2, and land-cover change (some including nitrogen–carbon interactions). We compare the mean land and ocean fluxes and their variability to estimates from three atmospheric inverse methods for three broad latitude bands. All uncertainties are reported as ±1σ, reflecting the current capacity to characterise the annual estimates of each component of the global carbon budget. For the last decade available (2005–2014), EFF was 9.0 ± 0.5 GtC yr−1, ELUC was 0.9 ± 0.5 GtC yr−1, GATM was 4.4 ± 0.1 GtC yr−1, SOCEAN was 2.6 ± 0.5 GtC yr−1, and SLAND was 3.0 ± 0.8 GtC yr−1. For the year 2014 alone, EFF grew to 9.8 ± 0.5 GtC yr−1, 0.6 \% above 2013, continuing the growth trend in these emissions, albeit at a slower rate compared to the average growth of 2.2 \% yr−1 that took place during 2005–2014. Also, for 2014, ELUC was 1.1 ± 0.5 GtC yr−1, GATM was 3.9 ± 0.2 GtC yr−1, SOCEAN was 2.9 ± 0.5 GtC yr−1, and SLAND was 4.1 ± 0.9 GtC yr−1. GATM was lower in 2014 compared to the past decade (2005–2014), reflecting a larger SLAND for that year. The global atmospheric CO2 concentration reached 397.15 ± 0.10 ppm averaged over 2014. For 2015, preliminary data indicate that the growth in EFF will be near or slightly below zero, with a projection of −0.6 [range of −1.6 to +0.5] \%, based on national emissions projections for China and the USA, and projections of gross domestic product corrected for recent changes in the carbon intensity of the global economy for the rest of the world. From this projection of EFF and assumed constant ELUC for 2015, cumulative emissions of CO2 will reach about 555 ± 55 GtC (2035 ± 205 GtCO2) for 1870–2015, about 75 \% from EFF and 25 \% from ELUC. This living data update documents changes in the methods and data sets used in this new carbon budget compared with previous publications of this data set (Le Quéré et al., 2015, 2014, 2013). All observations presented here can be downloaded from the Carbon Dioxide Information Analysis Center (doi:10.3334/CDIAC/GCP\_2015).",
    url = "https://doi.org/10.5194/essd-7-349-2015",
    doi = "10.5194/essd-7-349-2015",
    openalex = "W2915309988",
    references = "doi1010292006gb002784, myhre2009a"
}

Abstract. Accurate assessment of anthropogenic carbon dioxide (CO2) emissions and their redistribution among the atmosphere, ocean, and terrestrial biosphere is important to better understand the global carbon cycle, support the development of climate policies, and project future climate change. Here we describe data sets and a methodology to quantify all major components of the global carbon budget, including their uncertainties, based on the combination of a range of data, algorithms, statistics, and model estimates and their interpretation by a broad scientific community. We discuss changes compared to previous estimates, consistency within and among components, alongside methodology and data limitations. CO2 emissions from fossil fuel combustion and cement production (EFF) are based on energy statistics and cement production data, respectively, while emissions from land-use change (ELUC), mainly deforestation, are based on combined evidence from land-cover-change data, fire activity associated with deforestation, and models. The global atmospheric CO2 concentration is measured directly and its rate of growth (GATM) is computed from the annual changes in concentration. The mean ocean CO2 sink (SOCEAN) is based on observations from the 1990s, while the annual anomalies and trends are estimated with ocean models. The variability in SOCEAN is evaluated with data products based on surveys of ocean CO2 measurements. The global residual terrestrial CO2 sink (SLAND) is estimated by the difference of the other terms of the global carbon budget and compared to results of independent dynamic global vegetation models forced by observed climate, CO2, and land-cover-change (some including nitrogen–carbon interactions). We compare the mean land and ocean fluxes and their variability to estimates from three atmospheric inverse methods for three broad latitude bands. All uncertainties are reported as ±1σ, reflecting the current capacity to characterise the annual estimates of each component of the global carbon budget. For the last decade available (2004–2013), EFF was 8.9 ± 0.4 GtC yr−1, ELUC 0.9 ± 0.5 GtC yr−1, GATM 4.3 ± 0.1 GtC yr−1, SOCEAN 2.6 ± 0.5 GtC yr−1, and SLAND 2.9 ± 0.8 GtC yr−1. For year 2013 alone, EFF grew to 9.9 ± 0.5 GtC yr−1, 2.3% above 2012, continuing the growth trend in these emissions, ELUC was 0.9 ± 0.5 GtC yr−1, GATM was 5.4 ± 0.2 GtC yr−1, SOCEAN was 2.9 ± 0.5 GtC yr−1, and SLAND was 2.5 ± 0.9 GtC yr−1. GATM was high in 2013, reflecting a steady increase in EFF and smaller and opposite changes between SOCEAN and SLAND compared to the past decade (2004–2013). The global atmospheric CO2 concentration reached 395.31 ± 0.10 ppm averaged over 2013. We estimate that EFF will increase by 2.5% (1.3–3.5%) to 10.1 ± 0.6 GtC in 2014 (37.0 ± 2.2 GtCO2 yr−1), 65% above emissions in 1990, based on projections of world gross domestic product and recent changes in the carbon intensity of the global economy. From this projection of EFF and assumed constant ELUC for 2014, cumulative emissions of CO2 will reach about 545 ± 55 GtC (2000 ± 200 GtCO2) for 1870–2014, about 75% from EFF and 25% from ELUC. This paper documents changes in the methods and data sets used in this new carbon budget compared with previous publications of this living data set (Le Quéré et al., 2013, 2014). All observations presented here can be downloaded from the Carbon Dioxide Information Analysis Center (doi:10.3334/CDIAC/GCP_2014).

@article{doi105194essd7472015,
    author = "Quéré, Corinne Le and Moriarty, R. and Andrew, Robbie M. and Peters, Glen P. and Ciais, Philippe and Friedlingstein, Pierre and Jones, S. D. M. and Sitch, Stephen and Tans, Pieter P. and Arneth, Almut and Boden, T. A. and Bopp, Laurent and Bozec, Yann and Canadell, Josep G. and Chini, Louise and Chevallier, Frédéric and Cosca, Catherine E and Harris, Ian and Hoppema, Mario and Houghton, R. A. and House, Joanna I. and Jain, Atul K. and Johannessen, Truls and Kato, Etsushi and Keeling, Ralph F. and Kitidis, Vassilis and Goldewijk, Kees Klein and Koven, Charles D. and Landa, Camilla S. and Landschützer, Peter and Lenton, Andrew and Lima, Ivan D. and Marland, Gregg and Mathis, Jeremy T. and Metzl, Nicolas and Nojiri, Yukihiro and Olsen, Are and Ono, Tsuneo and Peng, Shushi and Peters, Wouter and Pfeil, Benjamin and Poulter, Benjamin and Raupach, Michael and Regnier, Pierre and Rödenbeck, Christian and Saito, Shu and Salisbury, J. and Schuster, Ute and Schwinger, Jörg and Séférian, Roland and Segschneider, Joachim and Steinhoff, Tobias and Stocker, Benjamin D. and Sutton, Adrienne J. and Takahashi, Taro and Tilbrook, Bronte and van der Werf, Guido R. and Viovy, Nicolas and Wang, Ying‐Ping and Wanninkhof, Rik and Wiltshire, A. and Zeng, Ning",
    title = "Global carbon budget 2014",
    year = "2015",
    journal = "Earth system science data",
    abstract = "Abstract. Accurate assessment of anthropogenic carbon dioxide (CO2) emissions and their redistribution among the atmosphere, ocean, and terrestrial biosphere is important to better understand the global carbon cycle, support the development of climate policies, and project future climate change. Here we describe data sets and a methodology to quantify all major components of the global carbon budget, including their uncertainties, based on the combination of a range of data, algorithms, statistics, and model estimates and their interpretation by a broad scientific community. We discuss changes compared to previous estimates, consistency within and among components, alongside methodology and data limitations. CO2 emissions from fossil fuel combustion and cement production (EFF) are based on energy statistics and cement production data, respectively, while emissions from land-use change (ELUC), mainly deforestation, are based on combined evidence from land-cover-change data, fire activity associated with deforestation, and models. The global atmospheric CO2 concentration is measured directly and its rate of growth (GATM) is computed from the annual changes in concentration. The mean ocean CO2 sink (SOCEAN) is based on observations from the 1990s, while the annual anomalies and trends are estimated with ocean models. The variability in SOCEAN is evaluated with data products based on surveys of ocean CO2 measurements. The global residual terrestrial CO2 sink (SLAND) is estimated by the difference of the other terms of the global carbon budget and compared to results of independent dynamic global vegetation models forced by observed climate, CO2, and land-cover-change (some including nitrogen–carbon interactions). We compare the mean land and ocean fluxes and their variability to estimates from three atmospheric inverse methods for three broad latitude bands. All uncertainties are reported as ±1σ, reflecting the current capacity to characterise the annual estimates of each component of the global carbon budget. For the last decade available (2004–2013), EFF was 8.9 ± 0.4 GtC yr−1, ELUC 0.9 ± 0.5 GtC yr−1, GATM 4.3 ± 0.1 GtC yr−1, SOCEAN 2.6 ± 0.5 GtC yr−1, and SLAND 2.9 ± 0.8 GtC yr−1. For year 2013 alone, EFF grew to 9.9 ± 0.5 GtC yr−1, 2.3\% above 2012, continuing the growth trend in these emissions, ELUC was 0.9 ± 0.5 GtC yr−1, GATM was 5.4 ± 0.2 GtC yr−1, SOCEAN was 2.9 ± 0.5 GtC yr−1, and SLAND was 2.5 ± 0.9 GtC yr−1. GATM was high in 2013, reflecting a steady increase in EFF and smaller and opposite changes between SOCEAN and SLAND compared to the past decade (2004–2013). The global atmospheric CO2 concentration reached 395.31 ± 0.10 ppm averaged over 2013. We estimate that EFF will increase by 2.5\% (1.3–3.5\%) to 10.1 ± 0.6 GtC in 2014 (37.0 ± 2.2 GtCO2 yr−1), 65\% above emissions in 1990, based on projections of world gross domestic product and recent changes in the carbon intensity of the global economy. From this projection of EFF and assumed constant ELUC for 2014, cumulative emissions of CO2 will reach about 545 ± 55 GtC (2000 ± 200 GtCO2) for 1870–2014, about 75\% from EFF and 25\% from ELUC. This paper documents changes in the methods and data sets used in this new carbon budget compared with previous publications of this living data set (Le Quéré et al., 2013, 2014). All observations presented here can be downloaded from the Carbon Dioxide Information Analysis Center (doi:10.3334/CDIAC/GCP\_2014).",
    url = "https://doi.org/10.5194/essd-7-47-2015",
    doi = "10.5194/essd-7-47-2015",
    openalex = "W2154981955",
    references = "doi1010292006gb002784, doi105194bg1066992013"
}

Marine zooplankton comprise a phylogenetically and functionally diverse assemblage of protistan and metazoan consumers that occupy multiple trophic levels in pelagic food webs. Within this complex network, carbon flows via alternative zooplankton pathways drive temporal and spatial variability in production-grazing coupling, nutrient cycling, export, and transfer efficiency to higher trophic levels. We explore current knowledge of the processing of zooplankton food ingestion by absorption, egestion, respiration, excretion, and growth (production) processes. On a global scale, carbon fluxes are reasonably constrained by the grazing impact of microzooplankton and the respiratory requirements of mesozooplankton but are sensitive to uncertainties in trophic structure. The relative importance, combined magnitude, and efficiency of export mechanisms (mucous feeding webs, fecal pellets, molts, carcasses, and vertical migrations) likewise reflect regional variability in community structure. Climate change is expected to broadly alter carbon cycling by zooplankton and to have direct impacts on key species.

@article{doi101146annurevmarine010814015924,
    author = "Steinberg, Deborah K. and Landry, Michael R.",
    title = "Zooplankton and the Ocean Carbon Cycle",
    year = "2016",
    journal = "Annual Review of Marine Science",
    abstract = "Marine zooplankton comprise a phylogenetically and functionally diverse assemblage of protistan and metazoan consumers that occupy multiple trophic levels in pelagic food webs. Within this complex network, carbon flows via alternative zooplankton pathways drive temporal and spatial variability in production-grazing coupling, nutrient cycling, export, and transfer efficiency to higher trophic levels. We explore current knowledge of the processing of zooplankton food ingestion by absorption, egestion, respiration, excretion, and growth (production) processes. On a global scale, carbon fluxes are reasonably constrained by the grazing impact of microzooplankton and the respiratory requirements of mesozooplankton but are sensitive to uncertainties in trophic structure. The relative importance, combined magnitude, and efficiency of export mechanisms (mucous feeding webs, fecal pellets, molts, carcasses, and vertical migrations) likewise reflect regional variability in community structure. Climate change is expected to broadly alter carbon cycling by zooplankton and to have direct impacts on key species.",
    url = "https://doi.org/10.1146/annurev-marine-010814-015924",
    doi = "10.1146/annurev-marine-010814-015924",
    openalex = "W2461165776",
    references = "doi101007bf00397693, doi101016c20120027147, doi101023a1020591307260, doi10103835030078, doi101038374255a0, doi101038nature01017, doi101093icesjmsfsn048, doi101093plankt1761245, doi101093planktfbs062, doi101126science1153847, doi101126science1156401, doi101146annurevmarine010908163834, doi101146annurevmarine052913021325, doi101357002224007781567621, doi101890039000, doi104319lo20095441210, doi105194bg119952014"
}

Abstract. Accurate assessment of anthropogenic carbon dioxide (CO2) emissions and their redistribution among the atmosphere, ocean, and terrestrial biosphere – the “global carbon budget” – is important to better understand the global carbon cycle, support the development of climate policies, and project future climate change. Here we describe data sets and methodology to quantify all major components of the global carbon budget, including their uncertainties, based on the combination of a range of data, algorithms, statistics, and model estimates and their interpretation by a broad scientific community. We discuss changes compared to previous estimates and consistency within and among components, alongside methodology and data limitations. CO2 emissions from fossil fuels and industry (EFF) are based on energy statistics and cement production data, respectively, while emissions from land-use change (ELUC), mainly deforestation, are based on combined evidence from land-cover change data, fire activity associated with deforestation, and models. The global atmospheric CO2 concentration is measured directly and its rate of growth (GATM) is computed from the annual changes in concentration. The mean ocean CO2 sink (SOCEAN) is based on observations from the 1990s, while the annual anomalies and trends are estimated with ocean models. The variability in SOCEAN is evaluated with data products based on surveys of ocean CO2 measurements. The global residual terrestrial CO2 sink (SLAND) is estimated by the difference of the other terms of the global carbon budget and compared to results of independent dynamic global vegetation models. We compare the mean land and ocean fluxes and their variability to estimates from three atmospheric inverse methods for three broad latitude bands. All uncertainties are reported as ±1σ, reflecting the current capacity to characterise the annual estimates of each component of the global carbon budget. For the last decade available (2006–2015), EFF was 9.3 ± 0.5 GtC yr−1, ELUC 1.0 ± 0.5 GtC yr−1, GATM 4.5 ± 0.1 GtC yr−1, SOCEAN 2.6 ± 0.5 GtC yr−1, and SLAND 3.1 ± 0.9 GtC yr−1. For year 2015 alone, the growth in EFF was approximately zero and emissions remained at 9.9 ± 0.5 GtC yr−1, showing a slowdown in growth of these emissions compared to the average growth of 1.8 % yr−1 that took place during 2006–2015. Also, for 2015, ELUC was 1.3 ± 0.5 GtC yr−1, GATM was 6.3 ± 0.2 GtC yr−1, SOCEAN was 3.0 ± 0.5 GtC yr−1, and SLAND was 1.9 ± 0.9 GtC yr−1. GATM was higher in 2015 compared to the past decade (2006–2015), reflecting a smaller SLAND for that year. The global atmospheric CO2 concentration reached 399.4 ± 0.1 ppm averaged over 2015. For 2016, preliminary data indicate the continuation of low growth in EFF with +0.2 % (range of −1.0 to +1.8 %) based on national emissions projections for China and USA, and projections of gross domestic product corrected for recent changes in the carbon intensity of the economy for the rest of the world. In spite of the low growth of EFF in 2016, the growth rate in atmospheric CO2 concentration is expected to be relatively high because of the persistence of the smaller residual terrestrial sink (SLAND) in response to El Niño conditions of 2015–2016. From this projection of EFF and assumed constant ELUC for 2016, cumulative emissions of CO2 will reach 565 ± 55 GtC (2075 ± 205 GtCO2) for 1870–2016, about 75 % from EFF and 25 % from ELUC. This living data update documents changes in the methods and data sets used in this new carbon budget compared with previous publications of this data set (Le Quéré et al., 2015b, a, 2014, 2013). All observations presented here can be downloaded from the Carbon Dioxide Information Analysis Center (doi:10.3334/CDIAC/GCP_2016).

@article{doi105194essd86052016,
    author = "Quéré, Corinne Le and Andrew, Robbie M. and Canadell, Josep G. and Sitch, Stephen and Korsbakken, Jan Ivar and Peters, Glen P. and Manning, Andrew C. and Boden, Thomas A. and Tans, Pieter P. and Houghton, R. A. and Keeling, Ralph F. and Alin, Simone R. and Andrews, Oliver and Anthoni, Peter and Barbero, Leticia and Bopp, Laurent and Chevallier, Frédéric and Chini, Louise and Ciais, Philippe and Currie, Kim and Delire, Christine and Doney, Scott C. and Friedlingstein, Pierre and Gkritzalis, Thanos and Harris, Ian and Hauck, Judith and Haverd, Vanessa and Hoppema, Mario and Goldewijk, Kees Klein and Jain, Atul K. and Kato, Etsushi and Körtzinger, Arne and Landschützer, Peter and Lefèvre, Nathalie and Lenton, Andrew and Lienert, Sebastian and Lombardozzi, Danica and Melton, Joe R. and Metzl, Nicolas and Millero, Frank J. and Monteiro, Pedro M. S. and Munro, David R. and Nabel, Julia E. M. S. and Nakaoka, Shin‐Ichiro and O’Brien, Kevin and Olsen, Are and Omar, Abdirahman M and Ono, Tsuneo and Pierrot, Denis and Poulter, Benjamin and Rödenbeck, Christian and Salisbury, Joe and Schuster, Ute and Schwinger, Jörg and Séférian, Roland and Skjelvan, Ingunn and Stocker, Benjamin D. and Sutton, Adrienne J. and Takahashi, Taro and Tian, Hanqin and Tilbrook, Bronte and Luijkx, Ingrid T. and van der Werf, Guido R. and Viovy, Nicolas and Walker, Anthony P. and Wiltshire, A. and Zaehle, Sönke",
    title = "Global Carbon Budget 2016",
    year = "2016",
    journal = "Earth system science data",
    abstract = "Abstract. Accurate assessment of anthropogenic carbon dioxide (CO2) emissions and their redistribution among the atmosphere, ocean, and terrestrial biosphere – the “global carbon budget” – is important to better understand the global carbon cycle, support the development of climate policies, and project future climate change. Here we describe data sets and methodology to quantify all major components of the global carbon budget, including their uncertainties, based on the combination of a range of data, algorithms, statistics, and model estimates and their interpretation by a broad scientific community. We discuss changes compared to previous estimates and consistency within and among components, alongside methodology and data limitations. CO2 emissions from fossil fuels and industry (EFF) are based on energy statistics and cement production data, respectively, while emissions from land-use change (ELUC), mainly deforestation, are based on combined evidence from land-cover change data, fire activity associated with deforestation, and models. The global atmospheric CO2 concentration is measured directly and its rate of growth (GATM) is computed from the annual changes in concentration. The mean ocean CO2 sink (SOCEAN) is based on observations from the 1990s, while the annual anomalies and trends are estimated with ocean models. The variability in SOCEAN is evaluated with data products based on surveys of ocean CO2 measurements. The global residual terrestrial CO2 sink (SLAND) is estimated by the difference of the other terms of the global carbon budget and compared to results of independent dynamic global vegetation models. We compare the mean land and ocean fluxes and their variability to estimates from three atmospheric inverse methods for three broad latitude bands. All uncertainties are reported as ±1σ, reflecting the current capacity to characterise the annual estimates of each component of the global carbon budget. For the last decade available (2006–2015), EFF was 9.3 ± 0.5 GtC yr−1, ELUC 1.0 ± 0.5 GtC yr−1, GATM 4.5 ± 0.1 GtC yr−1, SOCEAN 2.6 ± 0.5 GtC yr−1, and SLAND 3.1 ± 0.9 GtC yr−1. For year 2015 alone, the growth in EFF was approximately zero and emissions remained at 9.9 ± 0.5 GtC yr−1, showing a slowdown in growth of these emissions compared to the average growth of 1.8 \% yr−1 that took place during 2006–2015. Also, for 2015, ELUC was 1.3 ± 0.5 GtC yr−1, GATM was 6.3 ± 0.2 GtC yr−1, SOCEAN was 3.0 ± 0.5 GtC yr−1, and SLAND was 1.9 ± 0.9 GtC yr−1. GATM was higher in 2015 compared to the past decade (2006–2015), reflecting a smaller SLAND for that year. The global atmospheric CO2 concentration reached 399.4 ± 0.1 ppm averaged over 2015. For 2016, preliminary data indicate the continuation of low growth in EFF with +0.2 \% (range of −1.0 to +1.8 \%) based on national emissions projections for China and USA, and projections of gross domestic product corrected for recent changes in the carbon intensity of the economy for the rest of the world. In spite of the low growth of EFF in 2016, the growth rate in atmospheric CO2 concentration is expected to be relatively high because of the persistence of the smaller residual terrestrial sink (SLAND) in response to El Niño conditions of 2015–2016. From this projection of EFF and assumed constant ELUC for 2016, cumulative emissions of CO2 will reach 565 ± 55 GtC (2075 ± 205 GtCO2) for 1870–2016, about 75 \% from EFF and 25 \% from ELUC. This living data update documents changes in the methods and data sets used in this new carbon budget compared with previous publications of this data set (Le Quéré et al., 2015b, a, 2014, 2013). All observations presented here can be downloaded from the Carbon Dioxide Information Analysis Center (doi:10.3334/CDIAC/GCP\_2016).",
    url = "https://doi.org/10.5194/essd-8-605-2016",
    doi = "10.5194/essd-8-605-2016",
    openalex = "W2916961622",
    references = "doi1010292006gb002784, myhre2009a"
}

Significance When the domestication of rice began in its homeland, China, is an enduring and important issue of debate for researchers from many different disciplines. Reliable chronological and robust identification criteria for rice domestication are keys to understanding the issue. Here, we first use phytolith dating to constrain the initial occupation of Shangshan, an important site with early rice remains located in the Lower Yangtze region of China. We then identify the rice phytoliths of Shangshan as partly domesticated based on their morphological characteristics. The results indicate that rice domestication may have begun at Shangshan in the Lower Yangtze during the beginning of the Holocene.

@article{doi101073pnas1704304114,
    author = "Zuo, Xinxin and Lu, Houyuan and Jiang, Le-ping. and Zhang, Jianping and Yang, Xiaoyan and Huan, X. and He, Keyang and Wang, Can and Wu, N.",
    title = "Dating rice remains through phytolith carbon-14 study reveals domestication at the beginning of the Holocene",
    year = "2017",
    journal = "Proceedings of the National Academy of Sciences",
    abstract = "Significance When the domestication of rice began in its homeland, China, is an enduring and important issue of debate for researchers from many different disciplines. Reliable chronological and robust identification criteria for rice domestication are keys to understanding the issue. Here, we first use phytolith dating to constrain the initial occupation of Shangshan, an important site with early rice remains located in the Lower Yangtze region of China. We then identify the rice phytoliths of Shangshan as partly domesticated based on their morphological characteristics. The results indicate that rice domestication may have begun at Shangshan in the Lower Yangtze during the beginning of the Holocene.",
    url = "https://www.pnas.org/content/pnas/114/25/6486.full.pdf",
    doi = "10.1073/pnas.1704304114",
    is_oa = "true",
    number = "25",
    pages = "6486-6491",
    semanticscholar_citation_count = "189",
    semanticscholar_id = "358a6705a540a34184e47b5d822d99bf63bfe43d",
    volume = "114"
}

production from all soil depths increased with 4°C warming; annual soil respiration increased by 34 to 37%. All depths responded to warming with similar temperature sensitivities, driven by decomposition of decadal-aged carbon. Whole-soil warming reveals a larger soil respiration response than many in situ experiments (most of which only warm the surface soil) and models.

@article{doi101126scienceaal1319,
    author = "Pries, Caitlin Hicks and Castanha, Cristina and Porras, Rachel and Torn, Margaret",
    title = "The whole-soil carbon flux in response to warming",
    year = "2017",
    journal = "Science",
    abstract = "production from all soil depths increased with 4°C warming; annual soil respiration increased by 34 to 37\%. All depths responded to warming with similar temperature sensitivities, driven by decomposition of decadal-aged carbon. Whole-soil warming reveals a larger soil respiration response than many in situ experiments (most of which only warm the surface soil) and models.",
    url = "https://doi.org/10.1126/science.aal1319",
    doi = "10.1126/science.aal1319",
    openalex = "W2593911960",
    references = "doi102458azujsrcv55i216177"
}

Abstract. The isotopic composition of carbon (Δ14C and δ13C) in atmospheric CO2 and in oceanic and terrestrial carbon reservoirs is influenced by anthropogenic emissions and by natural carbon exchanges, which can respond to and drive changes in climate. Simulations of 14C and 13C in the ocean and terrestrial components of Earth system models (ESMs) present opportunities for model evaluation and for investigation of carbon cycling, including anthropogenic CO2 emissions and uptake. The use of carbon isotopes in novel evaluation of the ESMs' component ocean and terrestrial biosphere models and in new analyses of historical changes may improve predictions of future changes in the carbon cycle and climate system. We compile existing data to produce records of Δ14C and δ13C in atmospheric CO2 for the historical period 1850–2015. The primary motivation for this compilation is to provide the atmospheric boundary condition for historical simulations in the Coupled Model Intercomparison Project 6 (CMIP6) for models simulating carbon isotopes in the ocean or terrestrial biosphere. The data may also be useful for other carbon cycle modelling activities.

@article{doi105194gmd1044052017,
    author = "Graven, Heather and Allison, Colin E. and Etheridge, David and Hammer, Samuel and Keeling, Ralph F. and Levin, Ingeborg and Meijer, Harro A. J. and Rubino, Mauro and Tans, Pieter P. and Trudinger, Cathy M. and Vaughn, Bruce H. and White, James W. C.",
    title = "Compiled records of carbon isotopes in atmospheric CO 2 for historical simulations in CMIP6",
    year = "2017",
    journal = "Geoscientific model development",
    abstract = "Abstract. The isotopic composition of carbon (Δ14C and δ13C) in atmospheric CO2 and in oceanic and terrestrial carbon reservoirs is influenced by anthropogenic emissions and by natural carbon exchanges, which can respond to and drive changes in climate. Simulations of 14C and 13C in the ocean and terrestrial components of Earth system models (ESMs) present opportunities for model evaluation and for investigation of carbon cycling, including anthropogenic CO2 emissions and uptake. The use of carbon isotopes in novel evaluation of the ESMs' component ocean and terrestrial biosphere models and in new analyses of historical changes may improve predictions of future changes in the carbon cycle and climate system. We compile existing data to produce records of Δ14C and δ13C in atmospheric CO2 for the historical period 1850–2015. The primary motivation for this compilation is to provide the atmospheric boundary condition for historical simulations in the Coupled Model Intercomparison Project 6 (CMIP6) for models simulating carbon isotopes in the ocean or terrestrial biosphere. The data may also be useful for other carbon cycle modelling activities.",
    url = "https://doi.org/10.5194/gmd-10-4405-2017",
    doi = "10.5194/gmd-10-4405-2017",
    openalex = "W2739472878",
    references = "doi101126science1223166415b, doi102458azujsrcv55i216177"
}

Tibetan permafrost largely formed during the late Pleistocene glacial period and shrank in the Holocene Thermal Maximum period. Quantifying the impacts of paleoclimatic extremes on soil carbon stock can shed light on the vulnerability of permafrost carbon in the future. Here, we synthesize data from 1114 sites across the Tibetan permafrost region to report that paleoclimate is more important than modern climate in shaping current permafrost carbon distribution, and its importance increases with soil depth, mainly through forming the soil's physiochemical properties. We derive a new estimate of modern soil carbon stock to 3 m depth by including the paleoclimate effects, and find that the stock ([Formula: see text] PgC) is triple that predicted by ecosystem models (11.5 ± 4.2 s.e.m PgC), which use pre-industrial climate to initialize the soil carbon pool. The discrepancy highlights the urgent need to incorporate paleoclimate information into model initialization for simulating permafrost soil carbon stocks.

@article{doi101038s41467019122145,
    author = "Ding, Jinzhi and Wang, Tao and Piao, Shilong and Smith, Pete and Zhang, Gan‐Lin and Yan, Zhengjie and Ren, Shuai and Liu, Dan and Wang, Shiping and Chen, Shengyun and Dai, Fuqiang and He, Jin and Li, Yingnian and Liu, Yongwen and Mao, Jiafu and Arain, A. M. and Tian, Hanqin and Shi, Xiaoying and Yang, Yuanhe and Zeng, Ning and Zhao, Lin",
    title = "The paleoclimatic footprint in the soil carbon stock of the Tibetan permafrost region",
    year = "2019",
    journal = "Nature Communications",
    abstract = "Tibetan permafrost largely formed during the late Pleistocene glacial period and shrank in the Holocene Thermal Maximum period. Quantifying the impacts of paleoclimatic extremes on soil carbon stock can shed light on the vulnerability of permafrost carbon in the future. Here, we synthesize data from 1114 sites across the Tibetan permafrost region to report that paleoclimate is more important than modern climate in shaping current permafrost carbon distribution, and its importance increases with soil depth, mainly through forming the soil's physiochemical properties. We derive a new estimate of modern soil carbon stock to 3 m depth by including the paleoclimate effects, and find that the stock ([Formula: see text] PgC) is triple that predicted by ecosystem models (11.5 ± 4.2 s.e.m PgC), which use pre-industrial climate to initialize the soil carbon pool. The discrepancy highlights the urgent need to incorporate paleoclimate information into model initialization for simulating permafrost soil carbon stocks.",
    url = "https://doi.org/10.1038/s41467-019-12214-5",
    doi = "10.1038/s41467-019-12214-5",
    openalex = "W2969766804",
    references = "doi101016jepsl201405017"
}

Abstract Annual growth rings are absent in many long-lived grassland geoxyles. Thus, estimates of age for individuals are largely based on non-benchmarked assessments by experienced botanists. We wished to obtain a more precise estimate of age from the xylopodia of four geoxylic taxa (i.e. Berkheya insignis, Callilepis laureola, Protea simplex and Tephrosia kraussiana) growing in a Pondoland grassland, using both the gas proportional counting and Accelerated Mass Spectroscopy radiocarbon dating techniques. Plants sampled in 2008 fell within modern concentrations of carbon 14; therefore, radiocarbon dating generally yielded two ages for each plant, an older age (range: 45–51 years, mean=49, CV=3.6%) corresponding with the nuclear testing period, and a younger age (range: 10–29 years, mean=18, CV=35%), corresponding to the period after the Partial Nuclear Test Ban Treaty. Hence the older ages are much less variable than the younger ages. All plants had the older age estimate, and all but two had the younger age estimate. In addition, two plants each, had two similar older age estimates. P. simplex plants were 16, 24, 27 and 29, or 45, 46–49, 47 and 49 years, T. kraussiana 13, 15 and 16, or 50 and two of 51 years, C. laureola 12, 15 and 21, or 49–50 and two of 50 years and B. insignis were 10, or 49, 50 and 51 years old. Growth rings were not visible with the naked eye. However, using stereomicroscopy, ring-like patterns were visible to some extent at 7X magnification for B. insignis, P. simplex and T. kraussiana, but not C. laureola. Counts of these structures were much lower than the younger 14C dates, and hence are unlikely to be annual rings. Despite the ambiguity of multiple ages, these estimates are a useful starting point or benchmark for future empirical investigations of age for forbs with no clear annual rings. Most studies have used radiocarbon dating to estimate the age of woody tree stem tissue, whereas this study is one of few to measure the age of below-ground modern tissues of South African forbs. Suggestions for further refinement during collection and processing of geophytic sample material are made based on lessons learned from this investigation.

@article{doi101016jsajb202006008,
    author = "Dayaram, A. and Witkowski, E. and Raimondo, D. and Bamford, M.",
    title = "Carbon-14 dating when there's no ring on it: Age of four Pondoland grassland geoxyles and lessons learned",
    year = "2020",
    journal = "South African Journal of Botany",
    abstract = "Abstract Annual growth rings are absent in many long-lived grassland geoxyles. Thus, estimates of age for individuals are largely based on non-benchmarked assessments by experienced botanists. We wished to obtain a more precise estimate of age from the xylopodia of four geoxylic taxa (i.e. Berkheya insignis, Callilepis laureola, Protea simplex and Tephrosia kraussiana) growing in a Pondoland grassland, using both the gas proportional counting and Accelerated Mass Spectroscopy radiocarbon dating techniques. Plants sampled in 2008 fell within modern concentrations of carbon 14; therefore, radiocarbon dating generally yielded two ages for each plant, an older age (range: 45–51 years, mean=49, CV=3.6\%) corresponding with the nuclear testing period, and a younger age (range: 10–29 years, mean=18, CV=35\%), corresponding to the period after the Partial Nuclear Test Ban Treaty. Hence the older ages are much less variable than the younger ages. All plants had the older age estimate, and all but two had the younger age estimate. In addition, two plants each, had two similar older age estimates. P. simplex plants were 16, 24, 27 and 29, or 45, 46–49, 47 and 49 years, T. kraussiana 13, 15 and 16, or 50 and two of 51 years, C. laureola 12, 15 and 21, or 49–50 and two of 50 years and B. insignis were 10, or 49, 50 and 51 years old. Growth rings were not visible with the naked eye. However, using stereomicroscopy, ring-like patterns were visible to some extent at 7X magnification for B. insignis, P. simplex and T. kraussiana, but not C. laureola. Counts of these structures were much lower than the younger 14C dates, and hence are unlikely to be annual rings. Despite the ambiguity of multiple ages, these estimates are a useful starting point or benchmark for future empirical investigations of age for forbs with no clear annual rings. Most studies have used radiocarbon dating to estimate the age of woody tree stem tissue, whereas this study is one of few to measure the age of below-ground modern tissues of South African forbs. Suggestions for further refinement during collection and processing of geophytic sample material are made based on lessons learned from this investigation.",
    url = "https://doi.org/10.1016/j.sajb.2020.06.008",
    doi = "10.1016/j.sajb.2020.06.008",
    is_oa = "true",
    pages = "415-422",
    semanticscholar_citation_count = "5",
    semanticscholar_id = "c6935cd9b3730650324269668de19872731c046a",
    volume = "132"
}

Abstract Radiocarbon calibration is necessary to correct for variations in atmospheric radiocarbon over time. The IntCal working group has developed an updated and extended radiocarbon calibration curve, IntCal20, for Northern Hemisphere terrestrial samples from 0 to 55,000 cal yr BP. This paper summarizes the new datasets, changes to existing datasets, and the statistical method used for constructing the new curve. Examples of the effect of the new calibration curve compared to IntCal13 for hypothetical radiocarbon ages are given. For the recent Holocene the effect is minimal, but for older radiocarbon ages the shift in calibrated ages can be up to several hundred years with the potential for multiple calibrated age ranges in periods with higher-resolution data. In addition, the IntCal20 curve is used to recalibrate the radiocarbon ages for the glaciation of the Puget Lowland and to recalculate the advance rate. The ice may have reached its maximum position a few hundred years earlier using the new calibration curve; the calculated advance rate is virtually unchanged from the prior estimate.

@article{doi101017qua202042,
    author = "Reimer, Paula",
    title = "Composition and consequences of the IntCal20 radiocarbon calibration curve",
    year = "2020",
    journal = "Quaternary Research",
    abstract = "Abstract Radiocarbon calibration is necessary to correct for variations in atmospheric radiocarbon over time. The IntCal working group has developed an updated and extended radiocarbon calibration curve, IntCal20, for Northern Hemisphere terrestrial samples from 0 to 55,000 cal yr BP. This paper summarizes the new datasets, changes to existing datasets, and the statistical method used for constructing the new curve. Examples of the effect of the new calibration curve compared to IntCal13 for hypothetical radiocarbon ages are given. For the recent Holocene the effect is minimal, but for older radiocarbon ages the shift in calibrated ages can be up to several hundred years with the potential for multiple calibrated age ranges in periods with higher-resolution data. In addition, the IntCal20 curve is used to recalibrate the radiocarbon ages for the glaciation of the Puget Lowland and to recalculate the advance rate. The ice may have reached its maximum position a few hundred years earlier using the new calibration curve; the calculated advance rate is virtually unchanged from the prior estimate.",
    url = "https://doi.org/10.1017/qua.2020.42",
    doi = "10.1017/qua.2020.42",
    openalex = "W3023118216",
    references = "doi101017rdc202068, doi102458azujsrc5516955"
}

ABSTRACT Radiocarbon (14 C) ages cannot provide absolutely dated chronologies for archaeological or paleoenvironmental studies directly but must be converted to calendar age equivalents using a calibration curve compensating for fluctuations in atmospheric 14 C concentration. Although calibration curves are constructed from independently dated archives, they invariably require revision as new data become available and our understanding of the Earth system improves. In this volume the international 14 C calibration curves for both the Northern and Southern Hemispheres, as well as for the ocean surface layer, have been updated to include a wealth of new data and extended to 55,000 cal BP. Based on tree rings, IntCal20 now extends as a fully atmospheric record to ca. 13,900 cal BP. For the older part of the timescale, IntCal20 comprises statistically integrated evidence from floating tree-ring chronologies, lacustrine and marine sediments, speleothems, and corals. We utilized improved evaluation of the timescales and location variable 14 C offsets from the atmosphere (reservoir age, dead carbon fraction) for each dataset. New statistical methods have refined the structure of the calibration curves while maintaining a robust treatment of uncertainties in the 14 C ages, the calendar ages and other corrections. The inclusion of modeled marine reservoir ages derived from a three-dimensional ocean circulation model has allowed us to apply more appropriate reservoir corrections to the marine 14 C data rather than the previous use of constant regional offsets from the atmosphere. Here we provide an overview of the new and revised datasets and the associated methods used for the construction of the IntCal20 curve and explore potential regional offsets for tree-ring data. We discuss the main differences with respect to the previous calibration curve, IntCal13, and some of the implications for archaeology and geosciences ranging from the recent past to the time of the extinction of the Neanderthals.

@article{doi101017rdc202041,
    author = "Reimer, Paula and Austin, William E. N. and Bard, Édouard and Bayliss, Alex and Blackwell, Paul G. and Ramsey, Christopher Bronk and Butzin, Martin and Cheng, Hai and Edwards, R. Lawrence and Friedrich, Michael and Grootes, Pieter Meiert and Guilderson, T. P. and Hajdas, Irka and Heaton, Timothy and Hogg, Alan and Hughen, Konrad A and Kromer, Bernd and Manning, Sturt W. and Muscheler, Raimund and Palmer, Jonathan and Pearson, Charlotte and van der Plicht, J. and Reimer, Ron and Richards, David A. and Scott, E. M. and Southon, John and Turney, Chris and Wacker, Lukas and Adolphi, Florian and Büntgen, Ulf and Capano, Manuela and Fahrni, Simon and Fogtmann-Schulz, Alexandra and Friedrich, Ronny and Köhler, Peter and Kudsk, Sabrina G K and Miyake, Fusa and Olsen, Jesper and Reinig, Frederick and Sakamoto, Minoru and Sookdeo, Adam and Talamo, Sahra",
    title = "The IntCal20 Northern Hemisphere Radiocarbon Age Calibration Curve (0–55 cal kBP)",
    year = "2020",
    journal = "Radiocarbon",
    abstract = "ABSTRACT Radiocarbon (14 C) ages cannot provide absolutely dated chronologies for archaeological or paleoenvironmental studies directly but must be converted to calendar age equivalents using a calibration curve compensating for fluctuations in atmospheric 14 C concentration. Although calibration curves are constructed from independently dated archives, they invariably require revision as new data become available and our understanding of the Earth system improves. In this volume the international 14 C calibration curves for both the Northern and Southern Hemispheres, as well as for the ocean surface layer, have been updated to include a wealth of new data and extended to 55,000 cal BP. Based on tree rings, IntCal20 now extends as a fully atmospheric record to ca. 13,900 cal BP. For the older part of the timescale, IntCal20 comprises statistically integrated evidence from floating tree-ring chronologies, lacustrine and marine sediments, speleothems, and corals. We utilized improved evaluation of the timescales and location variable 14 C offsets from the atmosphere (reservoir age, dead carbon fraction) for each dataset. New statistical methods have refined the structure of the calibration curves while maintaining a robust treatment of uncertainties in the 14 C ages, the calendar ages and other corrections. The inclusion of modeled marine reservoir ages derived from a three-dimensional ocean circulation model has allowed us to apply more appropriate reservoir corrections to the marine 14 C data rather than the previous use of constant regional offsets from the atmosphere. Here we provide an overview of the new and revised datasets and the associated methods used for the construction of the IntCal20 curve and explore potential regional offsets for tree-ring data. We discuss the main differences with respect to the previous calibration curve, IntCal13, and some of the implications for archaeology and geosciences ranging from the recent past to the time of the extinction of the Neanderthals.",
    url = "https://doi.org/10.1017/rdc.2020.41",
    doi = "10.1017/rdc.2020.41",
    openalex = "W3015391807",
    references = "doi101016jquascirev200504007, doi101016jquascirev201409007, doi101017rdc202059, doi101017rdc202068, doi101017s0033822200018397, doi101017s0033822200019123, doi101017s0033822200019172, doi101017s0033822200032999, doi101017s0033822200034202, doi101038nature02805, doi101038nature13636, doi101126science1059725, doi101126science1064618, doi101126science1226660, doi102458azujsrc5516947, doi102458azujsrc5516955, doi105194cp111532015, doi105194cp4472008, openalexw3135382233"
}

ABSTRACT To create a reliable radiocarbon calibration curve, one needs not only high-quality data but also a robust statistical methodology. The unique aspects of much of the calibration data provide considerable modeling challenges and require a made-to-measure approach to curve construction that accurately represents and adapts to these individualities, bringing the data together into a single curve. For IntCal20, the statistical methodology has undergone a complete redesign, from the random walk used in IntCal04, IntCal09 and IntCal13, to an approach based upon Bayesian splines with errors-in-variables. The new spline approach is still fitted using Markov Chain Monte Carlo (MCMC) but offers considerable advantages over the previous random walk, including faster and more reliable curve construction together with greatly increased flexibility and detail in modeling choices. This paper describes the new methodology together with the tailored modifications required to integrate the various datasets. For an end-user, the key changes include the recognition and estimation of potential over-dispersion in 14 C determinations, and its consequences on calibration which we address through the provision of predictive intervals on the curve; improvements to the modeling of rapid 14 C excursions and reservoir ages/dead carbon fractions; and modifications made to, hopefully, ensure better mixing of the MCMC which consequently increase confidence in the estimated curve.

@article{doi101017rdc202046,
    author = "Heaton, Timothy and Blaauw, Maarten and Blackwell, Paul G. and Ramsey, Christopher Bronk and Reimer, Paula and Scott, E. M.",
    title = "The IntCal20 Approach to Radiocarbon Calibration Curve Construction: A New Methodology Using Bayesian Splines and Errors-in-Variables",
    year = "2020",
    journal = "Radiocarbon",
    abstract = "ABSTRACT To create a reliable radiocarbon calibration curve, one needs not only high-quality data but also a robust statistical methodology. The unique aspects of much of the calibration data provide considerable modeling challenges and require a made-to-measure approach to curve construction that accurately represents and adapts to these individualities, bringing the data together into a single curve. For IntCal20, the statistical methodology has undergone a complete redesign, from the random walk used in IntCal04, IntCal09 and IntCal13, to an approach based upon Bayesian splines with errors-in-variables. The new spline approach is still fitted using Markov Chain Monte Carlo (MCMC) but offers considerable advantages over the previous random walk, including faster and more reliable curve construction together with greatly increased flexibility and detail in modeling choices. This paper describes the new methodology together with the tailored modifications required to integrate the various datasets. For an end-user, the key changes include the recognition and estimation of potential over-dispersion in 14 C determinations, and its consequences on calibration which we address through the provision of predictive intervals on the curve; improvements to the modeling of rapid 14 C excursions and reservoir ages/dead carbon fractions; and modifications made to, hopefully, ensure better mixing of the MCMC which consequently increase confidence in the estimated curve.",
    url = "https://doi.org/10.1017/rdc.2020.46",
    doi = "10.1017/rdc.2020.46",
    openalex = "W3039298458",
    references = "doi101017rdc202059, doi101017rdc202068"
}

ABSTRACT The concentration of radiocarbon (14 C) differs between ocean and atmosphere. Radiocarbon determinations from samples which obtained their 14 C in the marine environment therefore need a marine-specific calibration curve and cannot be calibrated directly against the atmospheric-based IntCal20 curve. This paper presents Marine20, an update to the internationally agreed marine radiocarbon age calibration curve that provides a non-polar global-average marine record of radiocarbon from 0–55 cal kBP and serves as a baseline for regional oceanic variation. Marine20 is intended for calibration of marine radiocarbon samples from non-polar regions; it is not suitable for calibration in polar regions where variability in sea ice extent, ocean upwelling and air-sea gas exchange may have caused larger changes to concentrations of marine radiocarbon. The Marine20 curve is based upon 500 simulations with an ocean/atmosphere/biosphere box-model of the global carbon cycle that has been forced by posterior realizations of our Northern Hemispheric atmospheric IntCal20 14 C curve and reconstructed changes in CO 2 obtained from ice core data. These forcings enable us to incorporate carbon cycle dynamics and temporal changes in the atmospheric 14 C level. The box-model simulations of the global-average marine radiocarbon reservoir age are similar to those of a more complex three-dimensional ocean general circulation model. However, simplicity and speed of the box model allow us to use a Monte Carlo approach to rigorously propagate the uncertainty in both the historic concentration of atmospheric 14 C and other key parameters of the carbon cycle through to our final Marine20 calibration curve. This robust propagation of uncertainty is fundamental to providing reliable precision for the radiocarbon age calibration of marine based samples. We make a first step towards deconvolving the contributions of different processes to the total uncertainty; discuss the main differences of Marine20 from the previous age calibration curve Marine13; and identify the limitations of our approach together with key areas for further work. The updated values for ΔR, the regional marine radiocarbon reservoir age corrections required to calibrate against Marine20, can be found at the data base http://calib.org/marine/.

@article{doi101017rdc202068,
    author = "Heaton, Timothy and Köhler, Peter and Butzin, Martin and Bard, Édouard and Reimer, Ron and Austin, William E. N. and Ramsey, Christopher Bronk and Grootes, Pieter Meiert and Hughen, Konrad A and Kromer, Bernd and Reimer, Paula and Adkins, Jess F. and Burke, Andrea and Cook, M. S. and Olsen, Jesper and Skinner, Luke C",
    title = "Marine20—The Marine Radiocarbon Age Calibration Curve (0–55,000 cal BP)",
    year = "2020",
    journal = "Radiocarbon",
    abstract = "ABSTRACT The concentration of radiocarbon (14 C) differs between ocean and atmosphere. Radiocarbon determinations from samples which obtained their 14 C in the marine environment therefore need a marine-specific calibration curve and cannot be calibrated directly against the atmospheric-based IntCal20 curve. This paper presents Marine20, an update to the internationally agreed marine radiocarbon age calibration curve that provides a non-polar global-average marine record of radiocarbon from 0–55 cal kBP and serves as a baseline for regional oceanic variation. Marine20 is intended for calibration of marine radiocarbon samples from non-polar regions; it is not suitable for calibration in polar regions where variability in sea ice extent, ocean upwelling and air-sea gas exchange may have caused larger changes to concentrations of marine radiocarbon. The Marine20 curve is based upon 500 simulations with an ocean/atmosphere/biosphere box-model of the global carbon cycle that has been forced by posterior realizations of our Northern Hemispheric atmospheric IntCal20 14 C curve and reconstructed changes in CO 2 obtained from ice core data. These forcings enable us to incorporate carbon cycle dynamics and temporal changes in the atmospheric 14 C level. The box-model simulations of the global-average marine radiocarbon reservoir age are similar to those of a more complex three-dimensional ocean general circulation model. However, simplicity and speed of the box model allow us to use a Monte Carlo approach to rigorously propagate the uncertainty in both the historic concentration of atmospheric 14 C and other key parameters of the carbon cycle through to our final Marine20 calibration curve. This robust propagation of uncertainty is fundamental to providing reliable precision for the radiocarbon age calibration of marine based samples. We make a first step towards deconvolving the contributions of different processes to the total uncertainty; discuss the main differences of Marine20 from the previous age calibration curve Marine13; and identify the limitations of our approach together with key areas for further work. The updated values for ΔR, the regional marine radiocarbon reservoir age corrections required to calibrate against Marine20, can be found at the data base http://calib.org/marine/.",
    url = "https://doi.org/10.1017/rdc.2020.68",
    doi = "10.1017/rdc.2020.68",
    openalex = "W3048882402",
    references = "doi1010029781119558378, doi101016jquascirev200504007, doi101017rdc202041, doi101017s0033822200033002, doi101017s0033822200034202, doi1010292004gb002247, doi1010292006gb002784, doi10102992jc00188, doi101038345405a0, doi1011111467986800294, doi101214ss1177012413, doi102458azujsrc5516947, doi103402tellusav27i29900, doi104319lom201412351, openalexw2053289371, openalexw3135382233"
}

ABSTRACT The last decade has seen the development of a range of new statistical and computational techniques for analysing large collections of radiocarbon (14 C) dates, often but not exclusively to make inferences about human population change in the past. Here we introduce rcarbon, an open-source software package for the R statistical computing language which implements many of these techniques and looks to foster transparent future study of their strengths and weaknesses. In this paper, we review the key assumptions, limitations and potentials behind statistical analyses of summed probability distribution of 14 C dates, including Monte-Carlo simulation-based tests, permutation tests, and spatial analyses. Supplementary material provides a fully reproducible analysis with further details not covered in the main paper.

@article{doi101017rdc202095,
    author = "Crema, Enrico R. and Bevan, Andrew",
    title = "INFERENCE FROM LARGE SETS OF RADIOCARBON DATES: SOFTWARE AND METHODS",
    year = "2020",
    journal = "Radiocarbon",
    abstract = "ABSTRACT The last decade has seen the development of a range of new statistical and computational techniques for analysing large collections of radiocarbon (14 C) dates, often but not exclusively to make inferences about human population change in the past. Here we introduce rcarbon, an open-source software package for the R statistical computing language which implements many of these techniques and looks to foster transparent future study of their strengths and weaknesses. In this paper, we review the key assumptions, limitations and potentials behind statistical analyses of summed probability distribution of 14 C dates, including Monte-Carlo simulation-based tests, permutation tests, and spatial analyses. Supplementary material provides a fully reproducible analysis with further details not covered in the main paper.",
    url = "https://doi.org/10.1017/rdc.2020.95",
    doi = "10.1017/rdc.2020.95",
    openalex = "W3092077505",
    references = "doi101017rdc2017108, doi101017rdc202041, doi101017rdc202059, doi101111j14754754200800394x"
}

@article{doi101038s415610200596z,
    author = "Shi, Zheng and Allison, Steven and He, Yujie and Levine, Paul A. and Hoyt, Alison M. and Beem‐Miller, Jeffrey and Zhu, Qing and Wieder, William R. and Trumbore, Susan and Randerson, James T.",
    title = "The age distribution of global soil carbon inferred from radiocarbon measurements",
    year = "2020",
    journal = "Nature Geoscience",
    url = "https://doi.org/10.1038/s41561-020-0596-z",
    doi = "10.1038/s41561-020-0596-z",
    openalex = "W3037501985",
    references = "doi102458azujsrcv55i216177"
}

ABSTRACT This paper presents a compilation of atmospheric radiocarbon for the period 1950–2019, derived from atmospheric CO 2 sampling and tree rings from clean-air sites. Following the approach taken by Hua et al. (2013), our revised and extended compilation consists of zonal, hemispheric and global radiocarbon (14 C) data sets, with monthly data sets for 5 zones (Northern Hemisphere zones 1, 2, and 3, and Southern Hemisphere zones 3 and 1–2). Our new compilation includes smooth curves for zonal data sets that are more suitable for dating applications than the previous approach based on simple averaging. Our new radiocarbon dataset is intended to help facilitate the use of atmospheric bomb 14 C in carbon cycle studies and to accommodate increasing demand for accurate dating of recent (post-1950) terrestrial samples.

@article{doi101017rdc202195,
    author = "Hua, Quan and Turnbull, Jocelyn and Santos, Guaciara M. and Rakowski, Andrzej and Ancapichún, Santiago and Pol‐Holz, Ricardo De and Hammer, Samuel and Lehman, Scott J. and Levin, Ingeborg and Miller, J. B. and Palmer, Jonathan and Turney, Chris",
    title = "ATMOSPHERIC RADIOCARBON FOR THE PERIOD 1950–2019",
    year = "2021",
    journal = "Radiocarbon",
    abstract = "ABSTRACT This paper presents a compilation of atmospheric radiocarbon for the period 1950–2019, derived from atmospheric CO 2 sampling and tree rings from clean-air sites. Following the approach taken by Hua et al. (2013), our revised and extended compilation consists of zonal, hemispheric and global radiocarbon (14 C) data sets, with monthly data sets for 5 zones (Northern Hemisphere zones 1, 2, and 3, and Southern Hemisphere zones 3 and 1–2). Our new compilation includes smooth curves for zonal data sets that are more suitable for dating applications than the previous approach based on simple averaging. Our new radiocarbon dataset is intended to help facilitate the use of atmospheric bomb 14 C in carbon cycle studies and to accommodate increasing demand for accurate dating of recent (post-1950) terrestrial samples.",
    url = "https://doi.org/10.1017/rdc.2021.95",
    doi = "10.1017/rdc.2021.95",
    openalex = "W3217627262",
    references = "doi101017rdc202041, doi101017rdc202059, doi101017s0033822200003672, doi101017s0033822200019172, doi101017s0033822200033142, doi101017s0033822200033154, doi1010292004gb002247, doi101073pnas1004933107, doi101126science1223166415b, doi1011751520047719960770437tnyrp20co2, doi102458azujsrcv55i216177, doi105860choice481462, openalexw1928750549, openalexw2571036723"
}

@article{doi101038s43586021000587,
    author = "Hajdas, Irka and Ascough, Philippa and Garnett, Mark H. and Fallon, Stewart and Pearson, Charlotte and Quarta, Gianluca and Spalding, Kirsty L. and Yamaguchi, H. and Yoneda, Minoru",
    title = "Radiocarbon dating",
    year = "2021",
    journal = "Nature Reviews Methods Primers",
    url = "https://doi.org/10.1038/s43586-021-00058-7",
    doi = "10.1038/s43586-021-00058-7",
    openalex = "W4211055559",
    references = "doi101017rdc202059, doi101017rdc202068, doi101098rsos201351, doi101126science1223166415b, doi102458azujsrc5516955"
}

Abstract. Accurate assessment of anthropogenic carbon dioxide (CO2) emissions and their redistribution among the atmosphere, ocean, and terrestrial biosphere in a changing climate is critical to better understand the global carbon cycle, support the development of climate policies, and project future climate change. Here we describe and synthesize datasets and methodology to quantify the five major components of the global carbon budget and their uncertainties. Fossil CO2 emissions (EFOS) are based on energy statistics and cement production data, while emissions from land-use change (ELUC), mainly deforestation, are based on land use and land-use change data and bookkeeping models. Atmospheric CO2 concentration is measured directly, and its growth rate (GATM) is computed from the annual changes in concentration. The ocean CO2 sink (SOCEAN) is estimated with global ocean biogeochemistry models and observation-based data products. The terrestrial CO2 sink (SLAND) is estimated with dynamic global vegetation models. The resulting carbon budget imbalance (BIM), the difference between the estimated total emissions and the estimated changes in the atmosphere, ocean, and terrestrial biosphere, is a measure of imperfect data and understanding of the contemporary carbon cycle. All uncertainties are reported as ±1σ. For the first time, an approach is shown to reconcile the difference in our ELUC estimate with the one from national greenhouse gas inventories, supporting the assessment of collective countries' climate progress. For the year 2020, EFOS declined by 5.4 % relative to 2019, with fossil emissions at 9.5 ± 0.5 GtC yr−1 (9.3 ± 0.5 GtC yr−1 when the cement carbonation sink is included), and ELUC was 0.9 ± 0.7 GtC yr−1, for a total anthropogenic CO2 emission of 10.2 ± 0.8 GtC yr−1 (37.4 ± 2.9 GtCO2). Also, for 2020, GATM was 5.0 ± 0.2 GtC yr−1 (2.4 ± 0.1 ppm yr−1), SOCEAN was 3.0 ± 0.4 GtC yr−1, and SLAND was 2.9 ± 1 GtC yr−1, with a BIM of −0.8 GtC yr−1. The global atmospheric CO2 concentration averaged over 2020 reached 412.45 ± 0.1 ppm. Preliminary data for 2021 suggest a rebound in EFOS relative to 2020 of +4.8 % (4.2 % to 5.4 %) globally. Overall, the mean and trend in the components of the global carbon budget are consistently estimated over the period 1959–2020, but discrepancies of up to 1 GtC yr−1 persist for the representation of annual to semi-decadal variability in CO2 fluxes. Comparison of estimates from multiple approaches and observations shows (1) a persistent large uncertainty in the estimate of land-use changes emissions, (2) a low agreement between the different methods on the magnitude of the land CO2 flux in the northern extra-tropics, and (3) a discrepancy between the different methods on the strength of the ocean sink over the last decade. This living data update documents changes in the methods and datasets used in this new global carbon budget and the progress in understanding of the global carbon cycle compared with previous publications of this dataset (Friedlingstein et al., 2020, 2019; Le Quéré et al., 2018b, a, 2016, 2015b, a, 2014, 2013). The data presented in this work are available at https://doi.org/10.18160/gcp-2021 (Friedlingstein et al., 2021).

@article{doi105194essd1419172022,
    author = "Friedlingstein, Pierre and Jones, Matthew W. and O’Sullivan, Michael and Andrew, Robbie M. and Bakker, Dorothée C. E. and Hauck, Judith and Quéré, Corinne Le and Peters, Glen P. and Peters, Wouter and Pongratz, Julia and Sitch, Stephen and Canadell, Josep G. and Ciais, Philippe and Jackson, Robert B. and Alin, Simone R. and Anthoni, Peter and Bates, Nicholas R. and Becker, Meike and Bellouin, Nicolas and Bopp, Laurent and Chau, Thi Tuyet Trang and Chevallier, Frédéric and Chini, Louise and Cronin, Margot and Currie, Kim and Decharme, Bertrand and Djeutchouang, Laique and Dou, Xinyu and Evans, Wiley and Feely, Richard A. and Feng, Liang and Gasser, Thomas and Gilfillan, Dennis and Gkritzalis, Thanos and Grassi, Giacomo and Gregor, Luke and Gruber, Nicolas and Gürses, Özgür and Harris, Ian and Houghton, R. A. and Hurtt, G. C. and Iida, Yosuke and Ilyina, Tatiana and Luijkx, Ingrid T. and Jain, Atul K. and Jones, S. D. M. and Kato, Etsushi and Kennedy, Daniel and Goldewijk, Kees Klein and Knauer, Jürgen and Korsbakken, Jan Ivar and Körtzinger, Arne and Landschützer, Peter and Lauvset, Siv K. and Lefèvre, Nathalie and Lienert, Sebastian and Liu, Junjie and Marland, Gregg and McGuire, Patrick and Melton, Joe R. and Munro, David R. and Nabel, Julia E. M. S. and Nakaoka, Shin‐Ichiro and Niwa, Yosuke and Ono, Tsuneo and Pierrot, Denis and Poulter, Benjamin and Rehder, Gregor and Resplandy, Laure and Robertson, Eddy and Rödenbeck, Christian and Rosan, Thais M. and Schwinger, Jörg and Schwingshackl, Clemens and Séférian, Roland and Sutton, Adrienne J. and Sweeney, Colm and Tanhua, Toste and Tans, Pieter P. and Tian, Hanqin and Tilbrook, Bronte and Tubiello, Francesco N. and van der Werf, Guido R. and Vuichard, Nicolas and Wada, Chisato and Wanninkhof, Rik and Watson, Andrew and Willis, David and Wiltshire, A. and Yuan, Wenping and Yue, Chao and Yue, Xu and Zaehle, Sönke and Zeng, Jiye",
    title = "Global Carbon Budget 2021",
    year = "2022",
    journal = "Earth system science data",
    abstract = "Abstract. Accurate assessment of anthropogenic carbon dioxide (CO2) emissions and their redistribution among the atmosphere, ocean, and terrestrial biosphere in a changing climate is critical to better understand the global carbon cycle, support the development of climate policies, and project future climate change. Here we describe and synthesize datasets and methodology to quantify the five major components of the global carbon budget and their uncertainties. Fossil CO2 emissions (EFOS) are based on energy statistics and cement production data, while emissions from land-use change (ELUC), mainly deforestation, are based on land use and land-use change data and bookkeeping models. Atmospheric CO2 concentration is measured directly, and its growth rate (GATM) is computed from the annual changes in concentration. The ocean CO2 sink (SOCEAN) is estimated with global ocean biogeochemistry models and observation-based data products. The terrestrial CO2 sink (SLAND) is estimated with dynamic global vegetation models. The resulting carbon budget imbalance (BIM), the difference between the estimated total emissions and the estimated changes in the atmosphere, ocean, and terrestrial biosphere, is a measure of imperfect data and understanding of the contemporary carbon cycle. All uncertainties are reported as ±1σ. For the first time, an approach is shown to reconcile the difference in our ELUC estimate with the one from national greenhouse gas inventories, supporting the assessment of collective countries' climate progress. For the year 2020, EFOS declined by 5.4 \% relative to 2019, with fossil emissions at 9.5 ± 0.5 GtC yr−1 (9.3 ± 0.5 GtC yr−1 when the cement carbonation sink is included), and ELUC was 0.9 ± 0.7 GtC yr−1, for a total anthropogenic CO2 emission of 10.2 ± 0.8 GtC yr−1 (37.4 ± 2.9 GtCO2). Also, for 2020, GATM was 5.0 ± 0.2 GtC yr−1 (2.4 ± 0.1 ppm yr−1), SOCEAN was 3.0 ± 0.4 GtC yr−1, and SLAND was 2.9 ± 1 GtC yr−1, with a BIM of −0.8 GtC yr−1. The global atmospheric CO2 concentration averaged over 2020 reached 412.45 ± 0.1 ppm. Preliminary data for 2021 suggest a rebound in EFOS relative to 2020 of +4.8 \% (4.2 \% to 5.4 \%) globally. Overall, the mean and trend in the components of the global carbon budget are consistently estimated over the period 1959–2020, but discrepancies of up to 1 GtC yr−1 persist for the representation of annual to semi-decadal variability in CO2 fluxes. Comparison of estimates from multiple approaches and observations shows (1) a persistent large uncertainty in the estimate of land-use changes emissions, (2) a low agreement between the different methods on the magnitude of the land CO2 flux in the northern extra-tropics, and (3) a discrepancy between the different methods on the strength of the ocean sink over the last decade. This living data update documents changes in the methods and datasets used in this new global carbon budget and the progress in understanding of the global carbon cycle compared with previous publications of this dataset (Friedlingstein et al., 2020, 2019; Le Quéré et al., 2018b, a, 2016, 2015b, a, 2014, 2013). The data presented in this work are available at https://doi.org/10.18160/gcp-2021 (Friedlingstein et al., 2021).",
    url = "https://doi.org/10.5194/essd-14-1917-2022",
    doi = "10.5194/essd-14-1917-2022",
    openalex = "W4225004802",
    references = "archer2009atmospheric, doi101002joc3711, doi1010160016703782901107, doi101016jdsr2200812009, doi1010292003gb002199, doi1010292006gb002784, doi10102992jc00188, doi101038nature14283, doi101038nature25138, doi101038s41467020189227, doi101038s4159702004533, doi101126science1097403, doi101126science1244693, doi102151jmsj2015001, doi1025607obp1342, doi104060ca9825en, doi105194acp10117072010, doi105194essd1021412018, doi105194essd1117832019, doi105194essd119592019, doi105194essd1232692020, doi105194essd1419172022, doi105194essd96972017, doi105194essd99272017, doi105194gmd919372016"
}

Abstract. Accurate assessment of anthropogenic carbon dioxide (CO2) emissions and their redistribution among the atmosphere, ocean, and terrestrial biosphere in a changing climate is critical to better understand the global carbon cycle, support the development of climate policies, and project future climate change. Here we describe and synthesize data sets and methodologies to quantify the five major components of the global carbon budget and their uncertainties. Fossil CO2 emissions (EFOS) are based on energy statistics and cement production data, while emissions from land-use change (ELUC), mainly deforestation, are based on land use and land-use change data and bookkeeping models. Atmospheric CO2 concentration is measured directly, and its growth rate (GATM) is computed from the annual changes in concentration. The ocean CO2 sink (SOCEAN) is estimated with global ocean biogeochemistry models and observation-based data products. The terrestrial CO2 sink (SLAND) is estimated with dynamic global vegetation models. The resulting carbon budget imbalance (BIM), the difference between the estimated total emissions and the estimated changes in the atmosphere, ocean, and terrestrial biosphere, is a measure of imperfect data and understanding of the contemporary carbon cycle. All uncertainties are reported as ±1σ. For the year 2021, EFOS increased by 5.1 % relative to 2020, with fossil emissions at 10.1 ± 0.5 GtC yr−1 (9.9 ± 0.5 GtC yr−1 when the cement carbonation sink is included), and ELUC was 1.1 ± 0.7 GtC yr−1, for a total anthropogenic CO2 emission (including the cement carbonation sink) of 10.9 ± 0.8 GtC yr−1 (40.0 ± 2.9 GtCO2). Also, for 2021, GATM was 5.2 ± 0.2 GtC yr−1 (2.5 ± 0.1 ppm yr−1), SOCEAN was 2.9 ± 0.4 GtC yr−1, and SLAND was 3.5 ± 0.9 GtC yr−1, with a BIM of −0.6 GtC yr−1 (i.e. the total estimated sources were too low or sinks were too high). The global atmospheric CO2 concentration averaged over 2021 reached 414.71 ± 0.1 ppm. Preliminary data for 2022 suggest an increase in EFOS relative to 2021 of +1.0 % (0.1 % to 1.9 %) globally and atmospheric CO2 concentration reaching 417.2 ppm, more than 50 % above pre-industrial levels (around 278 ppm). Overall, the mean and trend in the components of the global carbon budget are consistently estimated over the period 1959–2021, but discrepancies of up to 1 GtC yr−1 persist for the representation of annual to semi-decadal variability in CO2 fluxes. Comparison of estimates from multiple approaches and observations shows (1) a persistent large uncertainty in the estimate of land-use change emissions, (2) a low agreement between the different methods on the magnitude of the land CO2 flux in the northern extratropics, and (3) a discrepancy between the different methods on the strength of the ocean sink over the last decade. This living data update documents changes in the methods and data sets used in this new global carbon budget and the progress in understanding of the global carbon cycle compared with previous publications of this data set. The data presented in this work are available at https://doi.org/10.18160/GCP-2022 (Friedlingstein et al., 2022b).

@article{doi105194essd1448112022,
    author = "Friedlingstein, Pierre and O’Sullivan, Michael and Jones, Matthew W. and Andrew, Robbie M. and Gregor, Luke and Hauck, Judith and Quéré, Corinne Le and Luijkx, Ingrid T. and Olsen, Are and Peters, Glen P. and Peters, Wouter and Pongratz, Julia and Schwingshackl, Clemens and Sitch, Stephen and Canadell, Josep G. and Ciais, Philippe and Jackson, Robert B. and Alin, Simone R. and Alkama, Ramdane and Arneth, Almut and Arora, Vivek and Bates, Nicholas R. and Becker, Meike and Bellouin, Nicolas and Bittig, Henry C. and Bopp, Laurent and Chevallier, Frédéric and Chini, Louise and Cronin, Margot and Evans, Wiley and Falk, Stefanie and Feely, Richard A. and Gasser, Thomas and Gehlen, Marion and Gkritzalis, Thanos and Gloege, Lucas and Grassi, Giacomo and Gruber, Nicolas and Gürses, Özgür and Harris, Ian and Hefner, Matthew and Houghton, R. A. and Hurtt, G. C. and Iida, Yosuke and Ilyina, Tatiana and Jain, Atul K. and Jersild, Annika and Kadono, Koji and Kato, Etsushi and Kennedy, Daniel and Goldewijk, Kees Klein and Knauer, Jürgen and Korsbakken, Jan Ivar and Landschützer, Peter and Lefèvre, Nathalie and Lindsay, Keith and Liu, Junjie and Liu, Zhu and Marland, Gregg and Mayot, Nicolas and McGrath, Matthew J. and Metzl, Nicolas and Monacci, Natalie and Munro, David R. and Nakaoka, Shin‐Ichiro and Niwa, Yosuke and O’Brien, Kevin and Ono, Tsuneo and Palmer, Paul I. and Pan, Naiqing and Pierrot, Denis and Pocock, Katie and Poulter, Benjamin and Resplandy, Laure and Robertson, Eddy and Rödenbeck, Christian and Rodríguez, Carmen Dolores Arbelo and Rosan, Thais M. and Schwinger, Jörg and Séférian, Roland and Shutler, Jamie D. and Skjelvan, Ingunn and Steinhoff, Tobias and Sun, Qing and Sutton, Adrienne J. and Sweeney, Colm and Takao, Shintaro and Tanhua, Toste and Tans, Pieter P. and Tian, Xiangjun and Tian, Hanqin and Tilbrook, Bronte and Tsujino, Hiroyuki and Tubiello, Francesco N. and van der Werf, Guido R. and Walker, Anthony P. and Wanninkhof, Rik and Whitehead, Chris and Wranne, Anna Willstrand and Wright, Rebecca",
    title = "Global Carbon Budget 2022",
    year = "2022",
    journal = "Earth system science data",
    abstract = "Abstract. Accurate assessment of anthropogenic carbon dioxide (CO2) emissions and their redistribution among the atmosphere, ocean, and terrestrial biosphere in a changing climate is critical to better understand the global carbon cycle, support the development of climate policies, and project future climate change. Here we describe and synthesize data sets and methodologies to quantify the five major components of the global carbon budget and their uncertainties. Fossil CO2 emissions (EFOS) are based on energy statistics and cement production data, while emissions from land-use change (ELUC), mainly deforestation, are based on land use and land-use change data and bookkeeping models. Atmospheric CO2 concentration is measured directly, and its growth rate (GATM) is computed from the annual changes in concentration. The ocean CO2 sink (SOCEAN) is estimated with global ocean biogeochemistry models and observation-based data products. The terrestrial CO2 sink (SLAND) is estimated with dynamic global vegetation models. The resulting carbon budget imbalance (BIM), the difference between the estimated total emissions and the estimated changes in the atmosphere, ocean, and terrestrial biosphere, is a measure of imperfect data and understanding of the contemporary carbon cycle. All uncertainties are reported as ±1σ. For the year 2021, EFOS increased by 5.1 \% relative to 2020, with fossil emissions at 10.1 ± 0.5 GtC yr−1 (9.9 ± 0.5 GtC yr−1 when the cement carbonation sink is included), and ELUC was 1.1 ± 0.7 GtC yr−1, for a total anthropogenic CO2 emission (including the cement carbonation sink) of 10.9 ± 0.8 GtC yr−1 (40.0 ± 2.9 GtCO2). Also, for 2021, GATM was 5.2 ± 0.2 GtC yr−1 (2.5 ± 0.1 ppm yr−1), SOCEAN was 2.9 ± 0.4 GtC yr−1, and SLAND was 3.5 ± 0.9 GtC yr−1, with a BIM of −0.6 GtC yr−1 (i.e. the total estimated sources were too low or sinks were too high). The global atmospheric CO2 concentration averaged over 2021 reached 414.71 ± 0.1 ppm. Preliminary data for 2022 suggest an increase in EFOS relative to 2021 of +1.0 \% (0.1 \% to 1.9 \%) globally and atmospheric CO2 concentration reaching 417.2 ppm, more than 50 \% above pre-industrial levels (around 278 ppm). Overall, the mean and trend in the components of the global carbon budget are consistently estimated over the period 1959–2021, but discrepancies of up to 1 GtC yr−1 persist for the representation of annual to semi-decadal variability in CO2 fluxes. Comparison of estimates from multiple approaches and observations shows (1) a persistent large uncertainty in the estimate of land-use change emissions, (2) a low agreement between the different methods on the magnitude of the land CO2 flux in the northern extratropics, and (3) a discrepancy between the different methods on the strength of the ocean sink over the last decade. This living data update documents changes in the methods and data sets used in this new global carbon budget and the progress in understanding of the global carbon cycle compared with previous publications of this data set. The data presented in this work are available at https://doi.org/10.18160/GCP-2022 (Friedlingstein et al., 2022b).",
    url = "https://doi.org/10.5194/essd-14-4811-2022",
    doi = "10.5194/essd-14-4811-2022",
    openalex = "W4308697725",
    references = "archer2009atmospheric, doi101002joc3711, doi1010160016703782901107, doi101016jdsr2200812009, doi1010179781009157896004, doi1010292003gb002199, doi10102992jc00188, doi101038nature14283, doi101038nature25138, doi101038s41467020189227, doi101038s4159702004533, doi101073pnas0700609104, doi101073pnas1019576108, doi101126science1244693, doi1011751520044220020151609aiisas20co2, doi102151jmsj2015001, doi1025607obp1342, doi104060ca9825en, doi105194acp10117072010, doi105194essd1021412018, doi105194essd1117832019, doi105194essd119592019, doi105194essd1232692020, doi105194essd1419172022, doi105194essd1448112022, doi105194essd96972017, doi105194essd99272017, doi105194gmd919372016"
}

), fluorescence, and molecular compositions of riverine dissolved organic matters (DOM) in the Bailong River catchment, the eastern edge of the Tibetan Plateau to identify anthropogenic impacts on the C cycle. Human activities show limited impact on dissolved organic carbon (DOC) concentration, but significantly increased the age of DOC (from modern to ∼1600 yr B.P.) and changed the molecular compositions through agriculture and urbanization despite in the catchment with low population density. Agricultural activities indirectly increased the leaching of N-containing aged organic matter from deep soil to rivers. Urbanization released S-containing aged C from fossil products into rivers directly through wastewater. The aged DOC from agricultural activity and wastewater discharge was partly biolabile and/or photolabile. This study highlights that riverine C is sensitive to anthropogenic disturbance. Additionally, the study also emphasizes that human activities reintroduce aged DOC into the modern C cycle, which would accelerate the geological C cycle.

@article{doi101021acsest3c01593,
    author = "Nai, Hui and Zhong, Jun and Yi, Yuanbi and Lai, Manting and He, Ding and Dittmar, Thorsten and Liu, Cong‐Qiang and Li, Si‐Liang and Xu, Sheng",
    title = "Anthropogenic Disturbance Stimulates the Export of Dissolved Organic Carbon to Rivers on the Tibetan Plateau",
    year = "2023",
    journal = "Environmental Science \& Technology",
    abstract = "), fluorescence, and molecular compositions of riverine dissolved organic matters (DOM) in the Bailong River catchment, the eastern edge of the Tibetan Plateau to identify anthropogenic impacts on the C cycle. Human activities show limited impact on dissolved organic carbon (DOC) concentration, but significantly increased the age of DOC (from modern to ∼1600 yr B.P.) and changed the molecular compositions through agriculture and urbanization despite in the catchment with low population density. Agricultural activities indirectly increased the leaching of N-containing aged organic matter from deep soil to rivers. Urbanization released S-containing aged C from fossil products into rivers directly through wastewater. The aged DOC from agricultural activity and wastewater discharge was partly biolabile and/or photolabile. This study highlights that riverine C is sensitive to anthropogenic disturbance. Additionally, the study also emphasizes that human activities reintroduce aged DOC into the modern C cycle, which would accelerate the geological C cycle.",
    url = "https://doi.org/10.1021/acs.est.3c01593",
    doi = "10.1021/acs.est.3c01593",
    openalex = "W4380291711",
    references = "doi101002rcm2386, doi101016jorggeochem200903002, doi101017rdc202195, doi101021es032333c, doi101038nature06275, doi101038ngeo1830, doi1011112041210x13800, doi102475ajs2824401, doi104319lom20086230, doi104319lom20086572, doi105194essd1448112022"
}

for τ > 1 year, with 81% contributed by the non-advective-diffusive vertical flux owing to sinking particles and vertically migrating zooplankton. Nevertheless, export of organic carbon by mixing and other fluid transport of dissolved matter and suspended particles remains regionally important for meeting the respiratory carbon demand. Furthermore, the temperature dependence of the sequestration efficiency inferred from our inversion suggests that future global warming may intensify the recycling of organic matter in the upper ocean, potentially weakening the BCP.

@article{doi101038s41586023067724,
    author = "Wang, Wei‐Lei and Fu, Weiwei and Moigne, Frédéric A.C. Le and Letscher, Robert T. and Liu, Yi and Tang, Jin‐Ming and Primeau, François",
    title = "Biological carbon pump estimate based on multidecadal hydrographic data",
    year = "2023",
    journal = "Nature",
    abstract = "for τ > 1 year, with 81\% contributed by the non-advective-diffusive vertical flux owing to sinking particles and vertically migrating zooplankton. Nevertheless, export of organic carbon by mixing and other fluid transport of dissolved matter and suspended particles remains regionally important for meeting the respiratory carbon demand. Furthermore, the temperature dependence of the sequestration efficiency inferred from our inversion suggests that future global warming may intensify the recycling of organic matter in the upper ocean, potentially weakening the BCP.",
    url = "https://doi.org/10.1038/s41586-023-06772-4",
    doi = "10.1038/s41586-023-06772-4",
    openalex = "W4389391248",
    references = "doi1010022013gb004743, doi101017rdc202195, doi1010291999gb001229, doi1010292007gb003078, doi101038ngeo612, doi101038s41558020009182, doi101038s4158601910982, doi101146annurevmarine010814015924, doi1015159781400849079, doi105194gmd1020572017, doi105670oceanog2009109"
}

C) along with a suite of ecophysiological metrics in Pinus edulis trees experiencing either extreme short-term drought (-90% ambient precipitation plot, 2020-2021) or a decade of severe drought (-45% plot, 2010-2021). We tested the hypothesis that carbon starvation - consumption exceeding synthesis and storage - increases the age of sapwood NSC. One year of extreme drought had no impact on NSC pool size or age, despite significant reductions in predawn water potential, photosynthetic rates/capacity, and twig and needle growth. By contrast, long-term drought halved the age of the sapwood NSC pool, coupled with reductions in sapwood starch concentrations (-75%), basal area increment (-39%), and bole respiration rates (-28%). Our results suggest carbon starvation takes time, as tree carbon reserves appear resilient to extreme disturbance in the short term. However, after a decade of drought, trees apparently consumed old stored NSC to support metabolism.

@article{doi101111nph19119,
    author = "Peltier, Drew and Carbone, Mariah S. and McIntire, C. David and Robertson, N. and Thompson, R. Alex and Malone, Shealyn C. and LeMoine, Jim and Richardson, Andrew D. and McDowell, Nate G. and Adams, Henry D. and Pockman, William T. and Trowbridge, Amy M.",
    title = "Carbon starvation following a decade of experimental drought consumes old reserves in Pinus edulis",
    year = "2023",
    journal = "New Phytologist",
    abstract = "C) along with a suite of ecophysiological metrics in Pinus edulis trees experiencing either extreme short-term drought (-90\% ambient precipitation plot, 2020-2021) or a decade of severe drought (-45\% plot, 2010-2021). We tested the hypothesis that carbon starvation - consumption exceeding synthesis and storage - increases the age of sapwood NSC. One year of extreme drought had no impact on NSC pool size or age, despite significant reductions in predawn water potential, photosynthetic rates/capacity, and twig and needle growth. By contrast, long-term drought halved the age of the sapwood NSC pool, coupled with reductions in sapwood starch concentrations (-75\%), basal area increment (-39\%), and bole respiration rates (-28\%). Our results suggest carbon starvation takes time, as tree carbon reserves appear resilient to extreme disturbance in the short term. However, after a decade of drought, trees apparently consumed old stored NSC to support metabolism.",
    url = "https://doi.org/10.1111/nph.19119",
    doi = "10.1111/nph.19119",
    openalex = "W4383873084",
    references = "doi101016jdendro200801002, doi101017rdc202195, doi101038s415590170248x, doi101093jexbot51345659, doi101104pp110170704, doi101111j13653040200701708x, doi101126science1155121, doi101126scienceaab1833, doi101126scienceaaz9600, doi101146annurevpp24060173002511, doi1023071942040"
}

• Reservoirs have carbon source/ sink functions serving as sites for carbon flow and exchange. • The carbon cycle process in reservoirs is influenced by multi-factor mechanisms. • Future research directions for global reservoir carbon cycle include long-term, large-scale monitoring and modeling. Based on the focus on the role of reservoirs as carbon sources and sinks, this article explores their impact on the global carbon cycle. Reservoirs, which are “artificial lakes” created by human activities in rivers, are reviewed in terms of the key links in carbon cycling within reservoir areas, the influencing factors, and research methods related to carbon cycling and carbon emissions. By reviewing the literature on reservoir carbon cycling, we elucidate the mechanisms of carbon inputs, decomposition and transformation, carbon emissions, and carbon burial, summarizing the biogeochemical coupling processes of dissolved organic carbon (DOC), dissolved inorganic carbon (DIC), particulate organic carbon (POC), and particulate inorganic carbon (PIC) with hydrological conditions and nutrients. The study concludes that the reservoir carbon cycling process is influenced by the characteristics of the reservoirs themselves, hydrological and hydrodynamic conditions, physicochemical and nutrient conditions, and human activities. Additionally, we further clarify the applications of field sampling and analysis, modeling, remote sensing technology, and isotope techniques in reservoir carbon cycling. In the future, it is recommended to continue monitoring and simulating the reservoir carbon cycle processes on a long-term and large-scale basis, and to deeply explore the multifactorial mechanisms of reservoir construction in the global carbon cycle.

@article{doi101016jecolind2024112511,
    author = "Li, Chunhui and Wang, Yihan and Yi, Yujun and Wang, Xuan and Santos, Celso Augusto Guimarães and Liu, Qiang",
    title = "A review of reservoir carbon Cycling: Key Processes, influencing factors and research methods",
    year = "2024",
    journal = "Ecological Indicators",
    abstract = "• Reservoirs have carbon source/ sink functions serving as sites for carbon flow and exchange. • The carbon cycle process in reservoirs is influenced by multi-factor mechanisms. • Future research directions for global reservoir carbon cycle include long-term, large-scale monitoring and modeling. Based on the focus on the role of reservoirs as carbon sources and sinks, this article explores their impact on the global carbon cycle. Reservoirs, which are “artificial lakes” created by human activities in rivers, are reviewed in terms of the key links in carbon cycling within reservoir areas, the influencing factors, and research methods related to carbon cycling and carbon emissions. By reviewing the literature on reservoir carbon cycling, we elucidate the mechanisms of carbon inputs, decomposition and transformation, carbon emissions, and carbon burial, summarizing the biogeochemical coupling processes of dissolved organic carbon (DOC), dissolved inorganic carbon (DIC), particulate organic carbon (POC), and particulate inorganic carbon (PIC) with hydrological conditions and nutrients. The study concludes that the reservoir carbon cycling process is influenced by the characteristics of the reservoirs themselves, hydrological and hydrodynamic conditions, physicochemical and nutrient conditions, and human activities. Additionally, we further clarify the applications of field sampling and analysis, modeling, remote sensing technology, and isotope techniques in reservoir carbon cycling. In the future, it is recommended to continue monitoring and simulating the reservoir carbon cycle processes on a long-term and large-scale basis, and to deeply explore the multifactorial mechanisms of reservoir construction in the global carbon cycle.",
    url = "https://doi.org/10.1016/j.ecolind.2024.112511",
    doi = "10.1016/j.ecolind.2024.112511",
    openalex = "W4403410029",
    references = "doi101021acsest3c01593"
}

Soil organic carbon (SOC) sequestration has become a critical component of climate change mitigation strategies, offering a natural and economically viable means to mitigate atmospheric CO2 levels. Current practices in SOC sequestration auditing face limitations due to the requirement for carbon permanence, which can discourage landholders from participating due to long-term commitments and uncertainties. We propose the concept of the Soil Carbon Tonne-Year as a new unit of measurement for assessing SOC sequestration, focusing on the time-integrated amount of carbon stored in the soil. Soil carbon tonne-year measures SOC stock across different operational soil carbon pools (such as Mineral Associated Organic Carbon and Particulate Organic Carbon), each with its own mean residence time. This approach, based on physical rather than economic or climatic metrics, aims to offer a more accurate, flexible, and realistic method of accounting for SOC. Our examples suggest that the Soil Carbon Tonne-Year approach could significantly enhance management flexibility, potentially increasing land value and leading to sustainable gains over the long term.

@article{doi101016jsoisec2024100153,
    author = "Minasny, Budiman and McBratney, Alex B.",
    title = "Soil carbon tonne-year accounting: Crediting the additional time-integrated amount of carbon captured in soil",
    year = "2024",
    journal = "Soil Security",
    abstract = "Soil organic carbon (SOC) sequestration has become a critical component of climate change mitigation strategies, offering a natural and economically viable means to mitigate atmospheric CO2 levels. Current practices in SOC sequestration auditing face limitations due to the requirement for carbon permanence, which can discourage landholders from participating due to long-term commitments and uncertainties. We propose the concept of the Soil Carbon Tonne-Year as a new unit of measurement for assessing SOC sequestration, focusing on the time-integrated amount of carbon stored in the soil. Soil carbon tonne-year measures SOC stock across different operational soil carbon pools (such as Mineral Associated Organic Carbon and Particulate Organic Carbon), each with its own mean residence time. This approach, based on physical rather than economic or climatic metrics, aims to offer a more accurate, flexible, and realistic method of accounting for SOC. Our examples suggest that the Soil Carbon Tonne-Year approach could significantly enhance management flexibility, potentially increasing land value and leading to sustainable gains over the long term.",
    url = "https://doi.org/10.1016/j.soisec.2024.100153",
    doi = "10.1016/j.soisec.2024.100153",
    openalex = "W4400052921",
    references = "doi101016jsoilbio2023109095"
}

under high discharge, suggests that permafrost thawing boosts DIC production and export via enhancing soil respiration and weathering. These findings reveal the predominant role of warming in altering carbon lateral export by escalating concentrations and fluxes and modifying export patterns.

@article{doi101021acsest3c06777,
    author = "Xu, Sen and Li, Si‐Liang and Bufe, Aaron and Klaus, Marcus and Zhong, Jun and Wen, Hang and Chen, Shuai and Li, Li",
    title = "Escalating Carbon Export from High-Elevation Rivers in a Warming Climate",
    year = "2024",
    journal = "Environmental Science \& Technology",
    abstract = "under high discharge, suggests that permafrost thawing boosts DIC production and export via enhancing soil respiration and weathering. These findings reveal the predominant role of warming in altering carbon lateral export by escalating concentrations and fluxes and modifying export patterns.",
    url = "https://doi.org/10.1021/acs.est.3c06777",
    doi = "10.1021/acs.est.3c06777",
    openalex = "W4394726399",
    references = "doi101021acsest3c01593"
}

@article{doi101038s41586024076794,
    author = "Heaton, Timothy and Bard, Édouard and Bayliss, Alex and Blaauw, Maarten and Ramsey, Christopher Bronk and Reimer, Paula and Turney, Chris and Usoskin, Ilya",
    title = "Extreme solar storms and the quest for exact dating with radiocarbon",
    year = "2024",
    journal = "Nature",
    url = "https://doi.org/10.1038/s41586-024-07679-4",
    doi = "10.1038/s41586-024-07679-4",
    openalex = "W4402437907",
    references = "doi101016jforsciint2021111143"
}

One mechanism by which the ocean uptakes carbon dioxide is through the biological carbon fixation and its subsequent transport to the deep ocean, a process known as the biological carbon pump. Although the importance of the biological pump in the global carbon cycle has long been recognized, its actual contribution remains uncertain. Here, we quantify the carbon export from the upper ocean via the biological carbon pump by revealing the upper ocean dissolved oxygen balance. Calculations of dissolved oxygen budget quantified net oxygen removals from the upper ocean by physical processes (air–sea exchange, advection, and diffusion) and indicated net biological oxygen production that compensated for those removals. The derived oxygen production is converted to carbon units using the photosynthetic ratio, and inferred an estimated global annual carbon export through the biological pump of 7.36 ± 2.12 Pg C year−1 with providing insights into the overall ocean carbon cycle. The biological carbon pump exports about 7.36 Pg of carbon globally per year from the upper ocean, according to an estimation of the dissolved oxygen budget that accounts for air–sea exchange, advection, and diffusion.

@article{doi101038s43247024018867,
    author = "Yamaguchi, Ryohei and Kouketsu, Shinya and Kosugi, Naohiro and Ishii, Masao",
    title = "Global upper ocean dissolved oxygen budget for constraining the biological carbon pump",
    year = "2024",
    journal = "Communications Earth \& Environment",
    abstract = "One mechanism by which the ocean uptakes carbon dioxide is through the biological carbon fixation and its subsequent transport to the deep ocean, a process known as the biological carbon pump. Although the importance of the biological pump in the global carbon cycle has long been recognized, its actual contribution remains uncertain. Here, we quantify the carbon export from the upper ocean via the biological carbon pump by revealing the upper ocean dissolved oxygen balance. Calculations of dissolved oxygen budget quantified net oxygen removals from the upper ocean by physical processes (air–sea exchange, advection, and diffusion) and indicated net biological oxygen production that compensated for those removals. The derived oxygen production is converted to carbon units using the photosynthetic ratio, and inferred an estimated global annual carbon export through the biological pump of 7.36 ± 2.12 Pg C year−1 with providing insights into the overall ocean carbon cycle. The biological carbon pump exports about 7.36 Pg of carbon globally per year from the upper ocean, according to an estimation of the dissolved oxygen budget that accounts for air–sea exchange, advection, and diffusion.",
    url = "https://doi.org/10.1038/s43247-024-01886-7",
    doi = "10.1038/s43247-024-01886-7",
    openalex = "W4405419458",
    references = "doi101038s41586023067724"
}

The estimation of the postmortem interval for skeletal remains is a crucial aspect of forensic anthropology. This paper illustrates the importance of radiocarbon analysis for establishing medico-legal significance and supporting forensic identification, through the analysis of three case studies for which the years of both birth and death were investigated. In Audresselles, Northern France, a partial skull was discovered with no contextual information or identity. Radiocarbon dating yielded an average calibrated calendar age of 4232 BCE (92.5% probability), indicating significant archaeological value but no forensic relevance. In the second case, skeletal remains were found in the flooded underground of a historical fort at Wimereux, Northern France, also with no identity. Radiocarbon dating based on the bomb-pulse curve indicated a calibrated date of death in 1962 CE (37.3% probability) or 1974-1975 CE (58.1% probability), both surpassing the French statute of limitations. Lastly, a skeleton with a suspected identity was discovered near Valenciennes, Northern France, and various biological tissues underwent radiocarbon dating. A bone sample suggested a calibrated date of death of 1998-2002 CE (84.6% probability), differing from a hair sample (2013-2018 CE, 83.3% probability) because of the slower bone tissue remodeling process. DNA analysis confirmed the person's identity, reported missing a decade prior to the discovery of the remains, following the alignment of the radiocarbon results with the individual's year of birth based on dental tissues and year of death. These case studies reveal that traditional radiocarbon dating and bomb-pulse dating are essential tools for estimating the postmortem interval, providing mutual benefits for archaeologists, forensic anthropologists, and the criminal justice system. Key points: Traditional radiocarbon dating and bomb-pulse dating are essential tools to establish the archaeological relevance or medico-legal significance of human skeletal remains.Bomb-pulse dating enables assessment of an individual's years of birth and death.Bomb-pulse dating helps to narrow down the pool of candidates for identification.Radiocarbon analysis provides mutual benefits for archaeologists, forensic anthropologists, and the criminal justice system.

@article{doi101093fsrowae046,
    author = "Bertrand, Benoît and Clauzel, Thibault and Richardin, Pascale and Bécart, Anne and Morbidelli, Philippe and Hédouin, Valéry and Marques, Carina",
    title = "Application and implications of radiocarbon dating in forensic case work: when medico-legal significance meets archaeological relevance",
    year = "2024",
    journal = "Forensic Sciences Research",
    abstract = "The estimation of the postmortem interval for skeletal remains is a crucial aspect of forensic anthropology. This paper illustrates the importance of radiocarbon analysis for establishing medico-legal significance and supporting forensic identification, through the analysis of three case studies for which the years of both birth and death were investigated. In Audresselles, Northern France, a partial skull was discovered with no contextual information or identity. Radiocarbon dating yielded an average calibrated calendar age of 4232 BCE (92.5\% probability), indicating significant archaeological value but no forensic relevance. In the second case, skeletal remains were found in the flooded underground of a historical fort at Wimereux, Northern France, also with no identity. Radiocarbon dating based on the bomb-pulse curve indicated a calibrated date of death in 1962 CE (37.3\% probability) or 1974-1975 CE (58.1\% probability), both surpassing the French statute of limitations. Lastly, a skeleton with a suspected identity was discovered near Valenciennes, Northern France, and various biological tissues underwent radiocarbon dating. A bone sample suggested a calibrated date of death of 1998-2002 CE (84.6\% probability), differing from a hair sample (2013-2018 CE, 83.3\% probability) because of the slower bone tissue remodeling process. DNA analysis confirmed the person's identity, reported missing a decade prior to the discovery of the remains, following the alignment of the radiocarbon results with the individual's year of birth based on dental tissues and year of death. These case studies reveal that traditional radiocarbon dating and bomb-pulse dating are essential tools for estimating the postmortem interval, providing mutual benefits for archaeologists, forensic anthropologists, and the criminal justice system. Key points: Traditional radiocarbon dating and bomb-pulse dating are essential tools to establish the archaeological relevance or medico-legal significance of human skeletal remains.Bomb-pulse dating enables assessment of an individual's years of birth and death.Bomb-pulse dating helps to narrow down the pool of candidates for identification.Radiocarbon analysis provides mutual benefits for archaeologists, forensic anthropologists, and the criminal justice system.",
    url = "https://doi.org/10.1093/fsr/owae046",
    doi = "10.1093/fsr/owae046",
    openalex = "W4401714212",
    references = "doi101016jforsciint2021111143"
}

Soil microbes are essential for regulating carbon stocks under climate change. However, the uncertainty surrounding how microbial temperature responses control carbon losses under warming conditions highlights a significant gap in our climate change models. To address this issue, we conducted a fine-scale analysis of soil organic carbon composition under different temperature gradients and characterized the corresponding microbial growth and physiology across various paddy soils spanning 4000 km in China. Our results showed that warming altered the composition of organic matter, resulting in a reduction in carbohydrates of approximately 0.026% to 0.030% from humid subtropical regions to humid continental regions. These changes were attributed to a decrease in the proportion of cold-preferring bacteria, leading to significant soil carbon losses. Our findings suggest that intrinsic microbial temperature sensitivity plays a crucial role in determining the rate of soil organic carbon decomposition, providing insights into the temperature limitations faced by microbial activities and their impact on soil carbon-climate feedback.

@article{doi101111gcb17395,
    author = "Li, Sen and Delgado‐Baquerizo, Manuel and Ding, Jixian and Hu, Han and Huang, Weigen and Sun, Yishen and Ni, Haowei and Kuang, Yanyun and Yuan, Mengting and Zhou, Jizhong and Zhang, Jiabao and Liang, Yuting",
    title = "Intrinsic microbial temperature sensitivity and soil organic carbon decomposition in response to climate change",
    year = "2024",
    journal = "Global Change Biology",
    abstract = "Soil microbes are essential for regulating carbon stocks under climate change. However, the uncertainty surrounding how microbial temperature responses control carbon losses under warming conditions highlights a significant gap in our climate change models. To address this issue, we conducted a fine-scale analysis of soil organic carbon composition under different temperature gradients and characterized the corresponding microbial growth and physiology across various paddy soils spanning 4000 km in China. Our results showed that warming altered the composition of organic matter, resulting in a reduction in carbohydrates of approximately 0.026\% to 0.030\% from humid subtropical regions to humid continental regions. These changes were attributed to a decrease in the proportion of cold-preferring bacteria, leading to significant soil carbon losses. Our findings suggest that intrinsic microbial temperature sensitivity plays a crucial role in determining the rate of soil organic carbon decomposition, providing insights into the temperature limitations faced by microbial activities and their impact on soil carbon-climate feedback.",
    url = "https://doi.org/10.1111/gcb.17395",
    doi = "10.1111/gcb.17395",
    openalex = "W4399973616",
    references = "doi101038s41558023018930"
}

Stomatal closure during drought inhibits carbon uptake and may reduce a tree's defensive capacity. Limited carbon availability during drought may increase a tree's mortality risk, particularly if drought constrains trees' capacity to rapidly produce defenses during biotic attack. We parameterized a new model of conifer defense using physiological data on carbon reserves and chemical defenses before and after a simulated bark beetle attack in mature Pinus edulis under experimental drought. Attack was simulated using inoculations with a consistent bluestain fungus (Ophiostoma sp.) of Ips confusus, the main bark beetle colonizing this tree, to induce a defensive response. Trees with more carbon reserves produced more defenses but measured phloem carbon reserves only accounted for c. 23% of the induced defensive response. Our model predicted universal mortality if local reserves alone supported defense production, suggesting substantial remobilization and transport of stored resin or carbon reserves to the inoculation site. Our results show that de novo terpene synthesis represents only a fraction of the total measured phloem terpenes in P. edulis following fungal inoculation. Without direct attribution of phloem terpene concentrations to available carbon, many studies may be overestimating the scale and importance of de novo terpene synthesis in a tree's induced defense response.

@article{doi101111nph20051,
    author = "Thompson, R. Alex and Malone, Shealyn C. and Peltier, Drew and Six, Diana L. and Robertson, N. and de Oliveira, Celso and McIntire, C. David and Pockman, William T. and McDowell, Nate G. and Trowbridge, Amy M. and Adams, Henry D.",
    title = "Local carbon reserves are insufficient for phloem terpene induction during drought in Pinus edulis in response to bark beetle‐associated fungi",
    year = "2024",
    journal = "New Phytologist",
    abstract = "Stomatal closure during drought inhibits carbon uptake and may reduce a tree's defensive capacity. Limited carbon availability during drought may increase a tree's mortality risk, particularly if drought constrains trees' capacity to rapidly produce defenses during biotic attack. We parameterized a new model of conifer defense using physiological data on carbon reserves and chemical defenses before and after a simulated bark beetle attack in mature Pinus edulis under experimental drought. Attack was simulated using inoculations with a consistent bluestain fungus (Ophiostoma sp.) of Ips confusus, the main bark beetle colonizing this tree, to induce a defensive response. Trees with more carbon reserves produced more defenses but measured phloem carbon reserves only accounted for c. 23\% of the induced defensive response. Our model predicted universal mortality if local reserves alone supported defense production, suggesting substantial remobilization and transport of stored resin or carbon reserves to the inoculation site. Our results show that de novo terpene synthesis represents only a fraction of the total measured phloem terpenes in P. edulis following fungal inoculation. Without direct attribution of phloem terpene concentrations to available carbon, many studies may be overestimating the scale and importance of de novo terpene synthesis in a tree's induced defense response.",
    url = "https://doi.org/10.1111/nph.20051",
    doi = "10.1111/nph.20051",
    openalex = "W4401641848",
    references = "doi101111nph19119"
}

Drought predisposes forest trees to bark beetle-induced mortality, but the physiological mechanisms remain unclear. While drought-induced water and carbon limitations have been implicated in defensive failure and tree susceptibility, evidence demonstrating how these factors interact is scarce. We withheld water from mature, potted Pinus edulis and subsequently applied a double-stem girdle to inhibit carbohydrate transport from the crown and roots. Within this isolated segment we then elicited a defense response by inoculating trees with a bark beetle-fungal symbiont (Ophiostoma sp.). We quantified local mono- and sesquiterpenes (MST), nonstructural carbohydrates (NSC), and pressure potential of the inner bark. Both drought-stressed and watered trees had similar NSC concentrations just before inoculation and depleted NSC similarly following inoculation, yet MST induction (i.e. increased concentration and altered composition) was constrained only in drought-stressed trees. Thus, NSC consumption was largely unrelated to de novo MST synthesis. Instead, stoichiometric calculations show that induction originated largely from stored resin. Watered trees experiencing higher pressure potentials consistently induced higher MST concentrations. We demonstrate the importance of preformed resin toward an induced MST response in a semi-arid conifer where drought-constraints on defense occurred through biophysical limitations (i.e. reduced turgor hindering resin transport) rather than through substrate limitation.

@article{doi101111nph20218,
    author = "Malone, Shealyn C. and Thompson, R. Alex and Chow, Pak S. and de Oliveira, Celso R. and Landhäusser, Simon M. and Six, Diana L. and McCulloh, Katherine A. and Adams, Henry D. and Trowbridge, Amy M.",
    title = "Water, not carbon, drives drought‐constraints on stem terpene defense against simulated bark beetle attack in Pinus edulis",
    year = "2024",
    journal = "New Phytologist",
    abstract = "Drought predisposes forest trees to bark beetle-induced mortality, but the physiological mechanisms remain unclear. While drought-induced water and carbon limitations have been implicated in defensive failure and tree susceptibility, evidence demonstrating how these factors interact is scarce. We withheld water from mature, potted Pinus edulis and subsequently applied a double-stem girdle to inhibit carbohydrate transport from the crown and roots. Within this isolated segment we then elicited a defense response by inoculating trees with a bark beetle-fungal symbiont (Ophiostoma sp.). We quantified local mono- and sesquiterpenes (MST), nonstructural carbohydrates (NSC), and pressure potential of the inner bark. Both drought-stressed and watered trees had similar NSC concentrations just before inoculation and depleted NSC similarly following inoculation, yet MST induction (i.e. increased concentration and altered composition) was constrained only in drought-stressed trees. Thus, NSC consumption was largely unrelated to de novo MST synthesis. Instead, stoichiometric calculations show that induction originated largely from stored resin. Watered trees experiencing higher pressure potentials consistently induced higher MST concentrations. We demonstrate the importance of preformed resin toward an induced MST response in a semi-arid conifer where drought-constraints on defense occurred through biophysical limitations (i.e. reduced turgor hindering resin transport) rather than through substrate limitation.",
    url = "https://doi.org/10.1111/nph.20218",
    doi = "10.1111/nph.20218",
    openalex = "W4403804190",
    references = "doi101111nph19119"
}

China is rich in marine resources and has excellent potential for the development of oceanic carbon sinks. Ocean carbon sinks have shown broad application prospects, but the technical system for trading has not yet been perfected, the relevant legislation has not yet been established, etc. China should actively promote scientific research on ocean carbon sinks, improve the technical system of ocean carbon sinks, establish an ocean carbon sink trading system, and develop the eco-economy of ocean carbon sinks. It should also establish a sound system of laws and regulations to explore the potential of oceanic carbon sinks and contribute to the realization of China’s dual-carbon goal.

@article{doi103389fmars20241298372,
    author = "Xuezhi, Wei and Wang, Quansheng",
    title = "Policy suggestions for tapping the potential of ocean carbon sinks in the context of “double carbon” goals in China",
    year = "2024",
    journal = "Frontiers in Marine Science",
    abstract = "China is rich in marine resources and has excellent potential for the development of oceanic carbon sinks. Ocean carbon sinks have shown broad application prospects, but the technical system for trading has not yet been perfected, the relevant legislation has not yet been established, etc. China should actively promote scientific research on ocean carbon sinks, improve the technical system of ocean carbon sinks, establish an ocean carbon sink trading system, and develop the eco-economy of ocean carbon sinks. It should also establish a sound system of laws and regulations to explore the potential of oceanic carbon sinks and contribute to the realization of China’s dual-carbon goal.",
    url = "https://doi.org/10.3389/fmars.2024.1298372",
    doi = "10.3389/fmars.2024.1298372",
    openalex = "W4393053210",
    references = "doi101038s41586023067724"
}

In the global carbon cycle, atmospheric carbon emissions, both ‘natural’ and anthropogenic, are balanced by carbon uptake (i.e., sequestration) that mostly occurs via photosynthesis, plus a much smaller proportion via geological processes. Since the formation of the Earth about 4.54 billion years ago, the ratio between emitted and sequestered carbon has varied considerably, with atmospheric CO2 levels ranging from 100,000 ppm to a mere 100 ppm. Over this time, a huge amount of carbon has been sequestered due to photosynthesis and essentially removed from the cycle, being buried as fossil deposits of coal, oil, and gas. Relatively low atmospheric CO2 levels were the norm for the past 10 million years, and during the past million years, they averaged about 220 ppm. More recently, the Holocene epoch, starting ~11,700 years ago, has been a period of unusual climatic stability with relatively warm, moist conditions and low atmospheric CO2 levels of between 260 and 280 ppm. During the Holocene, stable conditions facilitated a social revolution with the domestication of crops and livestock, leading to urbanisation and the development of complex technologies. As part of the latter process, immense quantities of sequestered fossil carbon have recently been used as energy sources, resulting in a particularly rapid increase in CO2 emissions after 1950 CE to the current value of 424 ppm, with further rises to >800 ppm predicted by 2100. This is already perturbing the previously stable Holocene climate and threatening future food production and social stability. Today, the global carbon cycle has been shifted such that carbon sequestration is no longer keeping up with recent anthropogenic emissions. In order to address this imbalance, it is important to understand the roles of potential biological carbon sequestration systems and to devise strategies to facilitate net CO2 uptake; for example, via changes in the patterns of land use, such as afforestation, preventing deforestation, and facilitating agriculture–agroforestry transitions.

@article{doi103390earth5020010,
    author = "Murphy, Denis J.",
    title = "Biological Carbon Sequestration: From Deep History to the Present Day",
    year = "2024",
    journal = "Earth",
    abstract = "In the global carbon cycle, atmospheric carbon emissions, both ‘natural’ and anthropogenic, are balanced by carbon uptake (i.e., sequestration) that mostly occurs via photosynthesis, plus a much smaller proportion via geological processes. Since the formation of the Earth about 4.54 billion years ago, the ratio between emitted and sequestered carbon has varied considerably, with atmospheric CO2 levels ranging from 100,000 ppm to a mere 100 ppm. Over this time, a huge amount of carbon has been sequestered due to photosynthesis and essentially removed from the cycle, being buried as fossil deposits of coal, oil, and gas. Relatively low atmospheric CO2 levels were the norm for the past 10 million years, and during the past million years, they averaged about 220 ppm. More recently, the Holocene epoch, starting \textasciitilde 11,700 years ago, has been a period of unusual climatic stability with relatively warm, moist conditions and low atmospheric CO2 levels of between 260 and 280 ppm. During the Holocene, stable conditions facilitated a social revolution with the domestication of crops and livestock, leading to urbanisation and the development of complex technologies. As part of the latter process, immense quantities of sequestered fossil carbon have recently been used as energy sources, resulting in a particularly rapid increase in CO2 emissions after 1950 CE to the current value of 424 ppm, with further rises to >800 ppm predicted by 2100. This is already perturbing the previously stable Holocene climate and threatening future food production and social stability. Today, the global carbon cycle has been shifted such that carbon sequestration is no longer keeping up with recent anthropogenic emissions. In order to address this imbalance, it is important to understand the roles of potential biological carbon sequestration systems and to devise strategies to facilitate net CO2 uptake; for example, via changes in the patterns of land use, such as afforestation, preventing deforestation, and facilitating agriculture–agroforestry transitions.",
    url = "https://doi.org/10.3390/earth5020010",
    doi = "10.3390/earth5020010",
    openalex = "W4399282902",
    references = "doi101016jearscirev2022104171"
}

Soil organic carbon (SOC) is the largest actively cycling reservoir of terrestrial carbon (C), and its stability plays a crucial role in carbon-climate feedback. However, the global distribution and environmental controlling factors of SOC stability across Earth's biomes remain unclear due to data limitation and complex interactions between climate, soil properties and land cover types. This study synthesized 11,495 globally distributed observations to the proportion of mineral-associated organic carbon (MAOC) in SOC (f MAOC), an indicator of soil carbon stability, in topsoil (0-30 cm) and subsoil (30-100 cm) across diverse climate zones and land cover types. We identified the key factors using forward recursive feature selection (FRFS) with the Random Forest model, and generated global distribution of f MAOC in topsoil and subsoil at 1 km resolution. Our results showed that a greater proportion of SOC in Earth's mineral soils is stored as MAOC in the subsoil (78.62%) compared to the topsoil (66.62%). Across climate zones and land cover types, temperate forests exhibited notable variation between topsoil (59.65%) and subsoil (73.73%), whereas cropland showed minimal difference, with subsoil only 6.54% higher than topsoil. The tundra in Boreal was the most vulnerable to C loss, with subsoil showing lower f MAOC than its topsoil counterpart. The f MAOC was jointly influenced by climate, soil properties, and land cover types, clay (contributed for 12.12% in topsoil and 14.83% in subsoil) and mean annual temperature (8.50% in topsoil and 14.07% in subsoil) were the predominant controlling factors at two depth intervals. Meanwhile, nitrogen deposition (8.63%) was important in determining f MAOC in topsoil, while elevation (12.63%) was important in subsoil. A high spatial heterogeneity and regional variation of f MAOC were observed at a global scale. These findings underscore the importance of quantifying and modeling the f MAOC to accurately predict the response of SOC storage to global change, ultimately informing strategies for SOC sequestration, climate change mitigation, and sustainable land management. • The majority of SOC in Earth's mineral soils was stored as MAOC in the topsoil (66.62%) and subsoil (78.62%). • The f MAOC was jointly influenced by climate, soil properties, and land cover. • Clay and MAT were the dominant controls of f MAOC in two depth intervals. • High spatial heterogeneity and regional variation of f MAOC were observed.

@article{doi101016jecz2025100035,
    author = "Zhao, Jiangjia and Minasny, Budiman and Setia, Raj and Zhou, Zhenghu and Ren, Chengjie and Biswas, Asim and Luo, Zhongkui and Zhou, Lianqing and Shi, Zhou and Chen, Songchao",
    title = "Global distribution and predictors of the mineral-associated to total soil organic carbon ratio: an indicator of soil carbon stability",
    year = "2025",
    journal = "Earth Critical Zone",
    abstract = "Soil organic carbon (SOC) is the largest actively cycling reservoir of terrestrial carbon (C), and its stability plays a crucial role in carbon-climate feedback. However, the global distribution and environmental controlling factors of SOC stability across Earth's biomes remain unclear due to data limitation and complex interactions between climate, soil properties and land cover types. This study synthesized 11,495 globally distributed observations to the proportion of mineral-associated organic carbon (MAOC) in SOC (f MAOC), an indicator of soil carbon stability, in topsoil (0-30 cm) and subsoil (30-100 cm) across diverse climate zones and land cover types. We identified the key factors using forward recursive feature selection (FRFS) with the Random Forest model, and generated global distribution of f MAOC in topsoil and subsoil at 1 km resolution. Our results showed that a greater proportion of SOC in Earth's mineral soils is stored as MAOC in the subsoil (78.62\%) compared to the topsoil (66.62\%). Across climate zones and land cover types, temperate forests exhibited notable variation between topsoil (59.65\%) and subsoil (73.73\%), whereas cropland showed minimal difference, with subsoil only 6.54\% higher than topsoil. The tundra in Boreal was the most vulnerable to C loss, with subsoil showing lower f MAOC than its topsoil counterpart. The f MAOC was jointly influenced by climate, soil properties, and land cover types, clay (contributed for 12.12\% in topsoil and 14.83\% in subsoil) and mean annual temperature (8.50\% in topsoil and 14.07\% in subsoil) were the predominant controlling factors at two depth intervals. Meanwhile, nitrogen deposition (8.63\%) was important in determining f MAOC in topsoil, while elevation (12.63\%) was important in subsoil. A high spatial heterogeneity and regional variation of f MAOC were observed at a global scale. These findings underscore the importance of quantifying and modeling the f MAOC to accurately predict the response of SOC storage to global change, ultimately informing strategies for SOC sequestration, climate change mitigation, and sustainable land management. • The majority of SOC in Earth's mineral soils was stored as MAOC in the topsoil (66.62\%) and subsoil (78.62\%). • The f MAOC was jointly influenced by climate, soil properties, and land cover. • Clay and MAT were the dominant controls of f MAOC in two depth intervals. • High spatial heterogeneity and regional variation of f MAOC were observed.",
    url = "https://doi.org/10.1016/j.ecz.2025.100035",
    doi = "10.1016/j.ecz.2025.100035",
    openalex = "W4412026402",
    references = "doi101016jsoilbio2023109095"
}

Radiocarbon analysis in bones, particularly through Bomb Pulse dating, is an essential tool in forensic investigations for estimating the postmortem interval of human remains. However, there are some limitations related to the interpretation of laboratory data, since this can differ from the Post Mortem Interval by many years, depending on the anatomical district and the bone part sampled, as well as the age of the individual and other parameters, since these elements influence bone turnover. In recent years, many studies have been conducted, but with non-standardized data and on limited samples. Therefore there is a need (experienced by the authors themselves in daily forensic practice when only bones are available) to summarize in a single work the data spread in the literature and try to standardize data, as much as possible, with limitation to forensic case only, in a review that is not only critical, but also systematic, in order to have specific and ready to use information for the interpretation of laboratory results. This work, therefore, not only aims to highlight the complexity and the need for standardized methodologies on multiple types of tissue for future research, but also to be an immediate help to refine the interpretation of the results provided by radiocorabion in order to have a Post Mortem Interval as reliable as possible.

@article{doi101016jforsciint2025112367,
    author = "Milani, Chantal and Tomassini, Luca and Gambelunghe, Cristiana and Pini, Niccolò and Calcagnile, Lucio and Quarta, Gianluca and D’Elia, Marisa and Scendoni, Roberto and Fedeli, Piergiorgio and Lancia, Massimo",
    title = "Radiocarbon and bomb pulse dating in the forensic context: A systematic review",
    year = "2025",
    journal = "Forensic Science International",
    abstract = "Radiocarbon analysis in bones, particularly through Bomb Pulse dating, is an essential tool in forensic investigations for estimating the postmortem interval of human remains. However, there are some limitations related to the interpretation of laboratory data, since this can differ from the Post Mortem Interval by many years, depending on the anatomical district and the bone part sampled, as well as the age of the individual and other parameters, since these elements influence bone turnover. In recent years, many studies have been conducted, but with non-standardized data and on limited samples. Therefore there is a need (experienced by the authors themselves in daily forensic practice when only bones are available) to summarize in a single work the data spread in the literature and try to standardize data, as much as possible, with limitation to forensic case only, in a review that is not only critical, but also systematic, in order to have specific and ready to use information for the interpretation of laboratory results. This work, therefore, not only aims to highlight the complexity and the need for standardized methodologies on multiple types of tissue for future research, but also to be an immediate help to refine the interpretation of the results provided by radiocorabion in order to have a Post Mortem Interval as reliable as possible.",
    url = "https://doi.org/10.1016/j.forsciint.2025.112367",
    doi = "10.1016/j.forsciint.2025.112367",
    openalex = "W4406211565",
    references = "doi101016jforsciint2021111143"
}

Abstract Within a collaboration between the Brazilian Federal Police and the Radiocarbon Laboratory of the Fluminense Federal University (LAC-UFF), this work studies seized art objects made from ivory. We aim to develop protocols to verify whether they are illegal according to the Convention on International Trade of Endangered Species from Wild Flora and Fauna (CITES) law by measuring the carbon-14 concentration in the modified ivory samples from different sampling spots and comparing it to the bomb peak curve. Over the course of this research, we evaluate the uncertainties related to the determination of the elephants’ death. These uncertainties are due to several factors such as the provenance of the elephants, growth pattern of the tusks and incorporation of atmospheric radiocarbon to the tissues, sampling methods of ivory objects of different sizes and shapes, and radiocarbon data analysis. This work is a pioneer study in Brazil and is likely to become a reference in the country in the field of radiocarbon analyses in forensic contexts.

@article{doi101017rdc202510164,
    author = "Silva, Karolayne and Macario, Kita C. D. and de Oliveira, Fabiana Monteiro and de Souza Coutinho Nogueira, Cauê and Xing, Yutao and Reis, Sérvio Túlio Jacinto",
    title = "Seized ivory in Brazil: Forensic analysis using radiocarbon dating at LAC-UFF",
    year = "2025",
    journal = "Radiocarbon",
    abstract = "Abstract Within a collaboration between the Brazilian Federal Police and the Radiocarbon Laboratory of the Fluminense Federal University (LAC-UFF), this work studies seized art objects made from ivory. We aim to develop protocols to verify whether they are illegal according to the Convention on International Trade of Endangered Species from Wild Flora and Fauna (CITES) law by measuring the carbon-14 concentration in the modified ivory samples from different sampling spots and comparing it to the bomb peak curve. Over the course of this research, we evaluate the uncertainties related to the determination of the elephants’ death. These uncertainties are due to several factors such as the provenance of the elephants, growth pattern of the tusks and incorporation of atmospheric radiocarbon to the tissues, sampling methods of ivory objects of different sizes and shapes, and radiocarbon data analysis. This work is a pioneer study in Brazil and is likely to become a reference in the country in the field of radiocarbon analyses in forensic contexts.",
    url = "https://www.semanticscholar.org/paper/c9fa5c540d1c751f0b2c0fea4d658ea6b768c085",
    doi = "10.1017/RDC.2025.10164",
    is_oa = "true",
    number = "1",
    pages = "155-166",
    semanticscholar_id = "c9fa5c540d1c751f0b2c0fea4d658ea6b768c085",
    volume = "68"
}

This study presents a comparative analysis of the radiocarbon dates obtained on paired samples of various organic materials extracted from a lake sediment core. AMS radiocarbon dating of bulk sediment, chironomid capsules, and Trapa seeds was conducted to assess whether systematic offsets exist in the dates obtained on material that are commonly used to develop chronological frameworks for lake-based paleoenvironmental research. The findings reveal significant discrepancies between 14 C dates obtained on bulk sediment, chironomid capsules, and on the Trapa seeds used to develop a previously published age-depth model for a sediment core recovered from Deoria Tal, Garhwal Himalaya, India. The systematic offset between the bulk sediment, and to a lesser extent chironomid remains, and the Trapa seeds is attributed to the integration of allochthonous carbon in the bulk sediment, leading to older apparent ages. The 3.6‰ shift in the δ 13 C value of the bulk sediment at 252 cm is inferred to reflect an increase in the contribution of C4 plant matter to the lake. The increase in enriched δ 13 C organic matter, coincident with the increasing offset between the dates obtained on bulk sediment and chironomids, and those obtained on the Trapa seeds, between 800 and 400 cal BP, was likely driven by anthropogenic land use changes, as evidenced by the four-fold increase in Cerealia-type pollen during this interval. This study underscores the necessity of selecting appropriate materials for radiocarbon dating to ensure accurate chronological reconstruction and highlights the potential of using chironomids remains to develop robust radiocarbon chronologies for lake sediment records.

@article{doi101017rdc202510174,
    author = "Rimal, Binita and Cherkinsky, Alexander and Porinchu, D. and Singh, A.",
    title = "A comparative analysis of the efficacy of dating various lake sediment-sourced materials for radiocarbon chronology development",
    year = "2025",
    journal = "Radiocarbon",
    abstract = "This study presents a comparative analysis of the radiocarbon dates obtained on paired samples of various organic materials extracted from a lake sediment core. AMS radiocarbon dating of bulk sediment, chironomid capsules, and Trapa seeds was conducted to assess whether systematic offsets exist in the dates obtained on material that are commonly used to develop chronological frameworks for lake-based paleoenvironmental research. The findings reveal significant discrepancies between 14 C dates obtained on bulk sediment, chironomid capsules, and on the Trapa seeds used to develop a previously published age-depth model for a sediment core recovered from Deoria Tal, Garhwal Himalaya, India. The systematic offset between the bulk sediment, and to a lesser extent chironomid remains, and the Trapa seeds is attributed to the integration of allochthonous carbon in the bulk sediment, leading to older apparent ages. The 3.6‰ shift in the δ 13 C value of the bulk sediment at 252 cm is inferred to reflect an increase in the contribution of C4 plant matter to the lake. The increase in enriched δ 13 C organic matter, coincident with the increasing offset between the dates obtained on bulk sediment and chironomids, and those obtained on the Trapa seeds, between 800 and 400 cal BP, was likely driven by anthropogenic land use changes, as evidenced by the four-fold increase in Cerealia-type pollen during this interval. This study underscores the necessity of selecting appropriate materials for radiocarbon dating to ensure accurate chronological reconstruction and highlights the potential of using chironomids remains to develop robust radiocarbon chronologies for lake sediment records.",
    url = "https://www.semanticscholar.org/paper/28d8306314c2e7772cbde878ac5e2b169d8fa6b3",
    doi = "10.1017/rdc.2025.10174",
    is_oa = "true",
    pages = "1-12",
    semanticscholar_citation_count = "1",
    semanticscholar_id = "28d8306314c2e7772cbde878ac5e2b169d8fa6b3"
}

, similar in magnitude to terrestrial net ecosystem exchange. A consequence of this flux is a greater than expected net loss of carbon from aged organic matter stores on land. This requires a reassessment of the fate of anthropogenic carbon in terrestrial systems and in global carbon cycle budgets and models.

@article{doi101038s4158602509023w,
    author = "Dean, Joshua and Coxon, Gemma and Zheng, Yanchen and Bishop, Jack B. and Garnett, Mark H. and Bastviken, David and Galy, Valier and Spencer, Robert G. M. and Tank, Suzanne E. and Tipper, Edward T. and Vonk, Jorien E. and Wallin, Marcus B. and Zhang, Liwei and Evans, Chris and Hilton, Robert",
    title = "Old carbon routed from land to the atmosphere by global river systems",
    year = "2025",
    journal = "Nature",
    abstract = ", similar in magnitude to terrestrial net ecosystem exchange. A consequence of this flux is a greater than expected net loss of carbon from aged organic matter stores on land. This requires a reassessment of the fate of anthropogenic carbon in terrestrial systems and in global carbon cycle budgets and models.",
    url = "https://doi.org/10.1038/s41586-025-09023-w",
    doi = "10.1038/s41586-025-09023-w",
    openalex = "W4411023786",
    references = "doi101002env2221, doi101017rdc202195, doi101017s0033822200003672, doi101023a1010933404324, doi101038nature08930, doi101038nature12760, doi101093bioscibix014, doi101136bmjn71, doi1018901051076120000100399aosoma20co2, doi1032614rj2017016, doi105194essd1448112022"
}

) and high connectivity of river loads with biological uptake.

@article{doi101038s41598025159265,
    author = "Chételat, John and Hebert, Craig E. and McClelland, Christine and Greenwood, Sarah",
    title = "Radiocarbon evidence of river transport and food web uptake of old carbon in Lake Athabasca, Canada",
    year = "2025",
    journal = "Scientific Reports",
    abstract = ") and high connectivity of river loads with biological uptake.",
    url = "https://doi.org/10.1038/s41598-025-15926-5",
    doi = "10.1038/s41598-025-15926-5",
    openalex = "W4413683926",
    references = "doi101038s4158602509023w"
}

→ metal atoms). These bonding situations enrich the carbon bonding models beyond traditional organic chemistry. This review provides a comprehensive summary of the recent findings regarding constrained carbon bonding with varying numbers of carbon atoms inside carbon cages. It will encompass crucial aspects of this special constrained carbon bonding such as the dispersion of negative charge on the carbon cage, reduction of Coulomb repulsion, maximization of coordinated metal ions, and determination of optimal configurations for metal atoms within the carbon cages. Accordingly, new carbon bonding could be identified in carbon cages, which holds significant implications in the development of innovative carbon-based compounds. Additionally, the current challenges faced and future developments anticipated from the aspect of confined carbon bonding inside carbon cages will be discussed to provide deeper insights into the intricacies of carbon bonding. Through this comprehensive exploration, we hope to advance knowledge in this exciting area of carbon chemistry.

@article{doi101039d5cs00481k,
    author = "Zhao, Yaoxiao and Li, Mengyang and Shen, Wangqiang and Guo, Kun and Bao, Lipiao and Lü, Xing",
    title = "Constrained carbon bonding inside fullerene cages",
    year = "2025",
    journal = "Chemical Society Reviews",
    abstract = "→ metal atoms). These bonding situations enrich the carbon bonding models beyond traditional organic chemistry. This review provides a comprehensive summary of the recent findings regarding constrained carbon bonding with varying numbers of carbon atoms inside carbon cages. It will encompass crucial aspects of this special constrained carbon bonding such as the dispersion of negative charge on the carbon cage, reduction of Coulomb repulsion, maximization of coordinated metal ions, and determination of optimal configurations for metal atoms within the carbon cages. Accordingly, new carbon bonding could be identified in carbon cages, which holds significant implications in the development of innovative carbon-based compounds. Additionally, the current challenges faced and future developments anticipated from the aspect of confined carbon bonding inside carbon cages will be discussed to provide deeper insights into the intricacies of carbon bonding. Through this comprehensive exploration, we hope to advance knowledge in this exciting area of carbon chemistry.",
    url = "https://doi.org/10.1039/d5cs00481k",
    doi = "10.1039/d5cs00481k",
    openalex = "W4416576502",
    references = "doi101038s4158602509023w"
}

Managing soils to increase organic carbon storage presents a potential opportunity to mitigate and adapt to global change challenges, while providing numerous co-benefits and ecosystem services. However, soils differ widely in their potential for carbon sequestration, and knowledge of biophysical limits to carbon accumulation may aid in informing priority regions. Consequently, there is great interest in assessing whether soils exhibit a maximum capacity for storing organic carbon, particularly within organo-mineral associations given the finite nature of reactive minerals in a soil. While the concept of soil carbon saturation has existed for over 25 years, recent studies have argued for and against its importance. Here, we summarize the conceptual understanding of soil carbon saturation at both micro- and macro-scales, define key terminology, and address common concerns and misconceptions. We review methods used to quantify soil carbon saturation, highlighting the theory and potential caveats of each approach. Critically, we explore the utility of the principles of soil carbon saturation for informing carbon accumulation, vulnerability to loss, and representations in process-based models. We highlight key knowledge gaps and propose next steps for furthering our mechanistic understanding of soil carbon saturation and its implications for soil management.

@article{doi101111gcb70197,
    author = "Georgiou, Katerina and Angers, Denis A. and Champiny, Ryan E. and Cotrufo, M. Francesca and Craig, Matthew E. and Döetterl, Sebastian and Grandy, A. Stuart and Lavallee, Jocelyn M. and Lin, Yang and Lugato, Emanuele and Poeplau, Christopher and Rocci, Katherine S. and Schweizer, Steffen A. and Six, Johan and Wieder, William R.",
    title = "Soil Carbon Saturation: What Do We Really Know?",
    year = "2025",
    journal = "Global Change Biology",
    abstract = "Managing soils to increase organic carbon storage presents a potential opportunity to mitigate and adapt to global change challenges, while providing numerous co-benefits and ecosystem services. However, soils differ widely in their potential for carbon sequestration, and knowledge of biophysical limits to carbon accumulation may aid in informing priority regions. Consequently, there is great interest in assessing whether soils exhibit a maximum capacity for storing organic carbon, particularly within organo-mineral associations given the finite nature of reactive minerals in a soil. While the concept of soil carbon saturation has existed for over 25 years, recent studies have argued for and against its importance. Here, we summarize the conceptual understanding of soil carbon saturation at both micro- and macro-scales, define key terminology, and address common concerns and misconceptions. We review methods used to quantify soil carbon saturation, highlighting the theory and potential caveats of each approach. Critically, we explore the utility of the principles of soil carbon saturation for informing carbon accumulation, vulnerability to loss, and representations in process-based models. We highlight key knowledge gaps and propose next steps for furthering our mechanistic understanding of soil carbon saturation and its implications for soil management.",
    url = "https://doi.org/10.1111/gcb.70197",
    doi = "10.1111/gcb.70197",
    openalex = "W4410242429",
    references = "doi101016jsoilbio2023109095"
}

Climate change is reshaping how forests balance carbon uptake and water loss. This review aims to clarify how climate change alters forest carbon–water coupling. Using water-use efficiency (WUE) as a unifying lens, we synthesize mechanisms from leaves to ecosystems and evaluate evidence from studies screened in 2000–2025 spanning eddy covariance, tree-ring isotopes, remote sensing and models. Globally, tree-ring data indicate ~40% intrinsic WUE increases since 1901, yet ecosystem-scale gains are usually <20% after accounting for mesophyll conductance. Under drought, heat and high vapor-pressure deficit, photosynthesis declines more than evapotranspiration, producing partial carbon–water decoupling and lower WUEe. Responses vary with hydraulic traits, forest type/age and site water balance, with notable tropical data gaps. We identify when WUE gains translate into true resilience: stomatal regulation and canopy structure jointly maintain GPP, prevent hydraulic failure and ensure post-event recovery. Management options include thinning, species/provenance choice, mixed stands and adaptive rotations to balance carbon storage with water yield. Key uncertainties stem from sparse long-term observations, tropical satellite biases and models that overestimate WUE or underplay extremes. We recommend integrating multi-source, multi-scale data with interpretable hybrid models, expanding tropical networks and strengthening MRV frameworks to support risk-aware, climate-smart forestry.

@article{doi103390su17219501,
    author = "Liang, Xiongwei and Cong, Xue and Du, Baolong and Ju, Yongfu and Wang, Yingning and Li, Dan",
    title = "Carbon–Water Coupling in Forest Ecosystems Under Climate Change: Advances in Water Use Efficiency and Sustainability Perspectives",
    year = "2025",
    journal = "Sustainability",
    abstract = "Climate change is reshaping how forests balance carbon uptake and water loss. This review aims to clarify how climate change alters forest carbon–water coupling. Using water-use efficiency (WUE) as a unifying lens, we synthesize mechanisms from leaves to ecosystems and evaluate evidence from studies screened in 2000–2025 spanning eddy covariance, tree-ring isotopes, remote sensing and models. Globally, tree-ring data indicate \textasciitilde 40\% intrinsic WUE increases since 1901, yet ecosystem-scale gains are usually <20\% after accounting for mesophyll conductance. Under drought, heat and high vapor-pressure deficit, photosynthesis declines more than evapotranspiration, producing partial carbon–water decoupling and lower WUEe. Responses vary with hydraulic traits, forest type/age and site water balance, with notable tropical data gaps. We identify when WUE gains translate into true resilience: stomatal regulation and canopy structure jointly maintain GPP, prevent hydraulic failure and ensure post-event recovery. Management options include thinning, species/provenance choice, mixed stands and adaptive rotations to balance carbon storage with water yield. Key uncertainties stem from sparse long-term observations, tropical satellite biases and models that overestimate WUE or underplay extremes. We recommend integrating multi-source, multi-scale data with interpretable hybrid models, expanding tropical networks and strengthening MRV frameworks to support risk-aware, climate-smart forestry.",
    url = "https://doi.org/10.3390/su17219501",
    doi = "10.3390/su17219501",
    openalex = "W4415684351",
    references = "doi101038s4158602509023w"
}

Global warming has triggered a surge in severe drought worldwide, disrupting vegetation photosynthesis and profoundly altering the global carbon cycle. However, the immediate and time-lagged responses of vegetation photosynthesis to warming drought remain unclear. Most current research on regional-scale solar-induced chlorophyll fluorescence (SIF) drought stress relies on daily or even monthly datasets, limiting insights into the diurnal dynamics of photosynthesis under drought. To address these gaps, we developed a continuous hourly SIF dataset (HC-SIF OCO) based on observations from Orbiting Carbon Observatory-2 (OCO-2) and OCO-3. HC-SIF OCO exhibited accuracy comparable to that of tower-based observations in terms of diurnal photosynthesis [SIF: R 2 ≥ 0.89, GPP (gross primary productivity): R 2 ≥ 0.94]. Then, we used this dataset to investigate the drought in the Yangtze River Basin in 2022. According to our analysis, the initial signs of drought-induced stress are reflected in a decrease in vegetation fluorescence efficiency, followed by anomalies in SIF and, finally, abnormalities in canopy structure. Drought has led to an approximately 3% increase in midday depression compared to previous years while also causing an advancement in the seasonal peak. Furthermore, immediate decreases in atmospheric moisture were responsible for more than 70% of the decline in vegetation photosynthesis, with soil dryness playing a 2-month-later role. Although temperature generally benefited photosynthesis, this effect diminished dramatically at midday. In summary, we present a new method for obtaining high-resolution temporal SIF data, providing new insights into the vegetation’s diurnal response to drought.

@article{doi1034133remotesensing0445,
    author = "Deng, Zhuoying and Chen, Jinghua and Wang, Shaoqiang and Li, Tingyu and Huang, Kun and Gu, Peng and Peng, Haoyu and Chen, Zhihui",
    title = "Response of Vegetation Photosynthesis to the 2022 Drought in Yangtze River Basin by Diurnal Orbiting Carbon Observatory-2/3 Satellite Observations",
    year = "2025",
    journal = "Journal of Remote Sensing",
    abstract = "Global warming has triggered a surge in severe drought worldwide, disrupting vegetation photosynthesis and profoundly altering the global carbon cycle. However, the immediate and time-lagged responses of vegetation photosynthesis to warming drought remain unclear. Most current research on regional-scale solar-induced chlorophyll fluorescence (SIF) drought stress relies on daily or even monthly datasets, limiting insights into the diurnal dynamics of photosynthesis under drought. To address these gaps, we developed a continuous hourly SIF dataset (HC-SIF OCO) based on observations from Orbiting Carbon Observatory-2 (OCO-2) and OCO-3. HC-SIF OCO exhibited accuracy comparable to that of tower-based observations in terms of diurnal photosynthesis [SIF: R 2 ≥ 0.89, GPP (gross primary productivity): R 2 ≥ 0.94]. Then, we used this dataset to investigate the drought in the Yangtze River Basin in 2022. According to our analysis, the initial signs of drought-induced stress are reflected in a decrease in vegetation fluorescence efficiency, followed by anomalies in SIF and, finally, abnormalities in canopy structure. Drought has led to an approximately 3\% increase in midday depression compared to previous years while also causing an advancement in the seasonal peak. Furthermore, immediate decreases in atmospheric moisture were responsible for more than 70\% of the decline in vegetation photosynthesis, with soil dryness playing a 2-month-later role. Although temperature generally benefited photosynthesis, this effect diminished dramatically at midday. In summary, we present a new method for obtaining high-resolution temporal SIF data, providing new insights into the vegetation’s diurnal response to drought.",
    url = "https://doi.org/10.34133/remotesensing.0445",
    doi = "10.34133/remotesensing.0445",
    openalex = "W4406759185",
    references = "doi101111nph19119"
}

Vicadrostat, also known as BI 690517 (1) is a novel, potent, and selective aldosterone synthase CYP11B2 inhibitor being developed in combination with empagliflozin to slow the progression of kidney damage and reduce cardiovascular events in people with chronic kidney diseases (CDK). The stable isotope labeled BI 690517 was obtained in a 12-step synthesis starting from aniline-13C6. The product was isolated with high chemical purity and enantiomeric excess. Carbon-14 labeled BI 690517 was prepared in one radioactive step from a chiral iodo-analog BI 764437 and zinc cyanide-14C. [14C]-1 was obtained with a specific activity of 55.6 mCi/mmol (2.05 GBq/mmol), chemical and radiochemical purities higher than 98%, and with enantiomeric excess higher than 99%. Vicadrostat undergoes extensive hepatic glucuronidation to form the O-glucuronide BI 689875 (2). Both carbon-13 and carbon-14 labeled BI 689875 were also synthesized.

@article{doi101002jlcr70026,
    author = "Latli, Bachir and Hrapchak, Matt and Chevliakov, Maxim and Samankumara, Lalith and Khattabi, Saad and Haddad, Nizar",
    title = "Synthesis of Carbon-13 and Carbon-14 Labeled BI 690517 (Vicadrostat) and Its O-Glucuronide Metabolite BI 689875.",
    year = "2026",
    journal = "Journal of labelled compounds \& radiopharmaceuticals",
    abstract = "Vicadrostat, also known as BI 690517 (1) is a novel, potent, and selective aldosterone synthase CYP11B2 inhibitor being developed in combination with empagliflozin to slow the progression of kidney damage and reduce cardiovascular events in people with chronic kidney diseases (CDK). The stable isotope labeled BI 690517 was obtained in a 12-step synthesis starting from aniline-13C6. The product was isolated with high chemical purity and enantiomeric excess. Carbon-14 labeled BI 690517 was prepared in one radioactive step from a chiral iodo-analog BI 764437 and zinc cyanide-14C. [14C]-1 was obtained with a specific activity of 55.6 mCi/mmol (2.05 GBq/mmol), chemical and radiochemical purities higher than 98\%, and with enantiomeric excess higher than 99\%. Vicadrostat undergoes extensive hepatic glucuronidation to form the O-glucuronide BI 689875 (2). Both carbon-13 and carbon-14 labeled BI 689875 were also synthesized.",
    url = "https://pubmed.ncbi.nlm.nih.gov/41944516/",
    doi = "10.1002/jlcr.70026",
    pmid = "41944516"
}

A new method to determine the 60Co impurity in 14C-urea capsules by liquid scintillation counting (LSC) has been developed. In this method, the counting signals produced by the Compton electrons of 60Co is used for 60Co analysis by selecting an appropriate region of interest in the LSC spectrum of the 14C-urea capsule sample. The spectral interferences caused by the high-activity 14C and the quench effect can be effectively eliminated by using a fixed sample preparation procedure. This method was validated by standard addition method using the commercial 14C-urea capsules and the results of 60Co activity are in good agreement with the expected values. The sensitivity of this method is calculated as ≤0.0064% for 60Co content and sufficiently competent for the limit test of <0.1% radio-impurity (including 60Co) in 14C-urea capsules. The method provides a practicable guidance for the radionuclidic purity test of 14C-urea capsules using LSC and can be directly applied in the routine quality test of 14C-urea capsules.

@article{doi101016japradiso2026112488,
    author = "Wang, Yadong and Wang, Yi and Dai, Xiongxin",
    title = "Limit test for cobalt-60 in carbon-14 urea capsules by liquid scintillation counting.",
    year = "2026",
    journal = "Applied radiation and isotopes: including data, instrumentation and methods for use in agriculture, industry and medicine",
    abstract = "A new method to determine the 60Co impurity in 14C-urea capsules by liquid scintillation counting (LSC) has been developed. In this method, the counting signals produced by the Compton electrons of 60Co is used for 60Co analysis by selecting an appropriate region of interest in the LSC spectrum of the 14C-urea capsule sample. The spectral interferences caused by the high-activity 14C and the quench effect can be effectively eliminated by using a fixed sample preparation procedure. This method was validated by standard addition method using the commercial 14C-urea capsules and the results of 60Co activity are in good agreement with the expected values. The sensitivity of this method is calculated as ≤0.0064\% for 60Co content and sufficiently competent for the limit test of <0.1\% radio-impurity (including 60Co) in 14C-urea capsules. The method provides a practicable guidance for the radionuclidic purity test of 14C-urea capsules using LSC and can be directly applied in the routine quality test of 14C-urea capsules.",
    url = "https://pubmed.ncbi.nlm.nih.gov/41689892/",
    doi = "10.1016/j.apradiso.2026.112488",
    pmid = "41689892"
}

The suitability of marine limpet shells for radiocarbon dating may depend on potential offsets due to diet and habitat, especially with regard to grazing mollusks on carbonate substrates (Dye 1994; England et al. 2013). A previous study on one grazing limpet species on the coast of Ireland found no offsets from carbonate substrates (Allen et al. 2019), but a similar study from mediterranean coasts found significant offsets on carbonate substrates (Ferguson et al. 2011). We carried out a new study of radiocarbon and stable carbon isotopes, using multiple species of mollusks collected live from the coasts of Gibraltar and Sardinia, from both carbonate and non-carbonate substrates. The 14 C results indicate that one species, inhabiting the upper shore, has a significant offset at the carbonate locations. This species, Patella rustica , has adapted to tolerate desiccation and may have biological traits that result in higher metabolic-derived carbon incorporated in its shell. The results of this preliminary study imply that selected species of grazing mollusks are suitable for radiocarbon dating, even in areas of carbonate geology.

@article{doi101017rdc202510184,
    author = "Allen, K. and Fa, D.",
    title = "14 C offsets in marine limpets: Observations on upper-shore mollusks and implications for their use in radiocarbon dating",
    year = "2026",
    journal = "Radiocarbon",
    abstract = "The suitability of marine limpet shells for radiocarbon dating may depend on potential offsets due to diet and habitat, especially with regard to grazing mollusks on carbonate substrates (Dye 1994; England et al. 2013). A previous study on one grazing limpet species on the coast of Ireland found no offsets from carbonate substrates (Allen et al. 2019), but a similar study from mediterranean coasts found significant offsets on carbonate substrates (Ferguson et al. 2011). We carried out a new study of radiocarbon and stable carbon isotopes, using multiple species of mollusks collected live from the coasts of Gibraltar and Sardinia, from both carbonate and non-carbonate substrates. The 14 C results indicate that one species, inhabiting the upper shore, has a significant offset at the carbonate locations. This species, Patella rustica , has adapted to tolerate desiccation and may have biological traits that result in higher metabolic-derived carbon incorporated in its shell. The results of this preliminary study imply that selected species of grazing mollusks are suitable for radiocarbon dating, even in areas of carbonate geology.",
    url = "https://www.semanticscholar.org/paper/27779722f07109da2eb97370769603253e8bd29c",
    doi = "10.1017/rdc.2025.10184",
    is_oa = "true",
    pages = "1-14",
    semanticscholar_id = "27779722f07109da2eb97370769603253e8bd29c"
}

UNLABELLED: Integrating livestock with crop farming can greatly enhance agricultural sustainability and accelerate the agroecological transition. This study investigated the five-year effects of oxen grazing in a vineyard in South-Tyrol (Italy). Grazing occurred from autumn to spring over five consecutive years at a density of 5–7 oxen ha− 1. An adjacent site remained ungrazed. Soil samples were collected and analyzed for soil carbon pools (elemental analyzer), compaction (bulk density), soil structure (micro–water-stable aggregates, µWSA < 63 μm; macro-water-stable-aggregates, MWSA < 250 μm), plant available elements (ICP-MS), total microbial biomass (fumigation and extraction) and microbial abundance (qPCR). The results showed that, despite both fields being pedogenically similar, oxen grazing improved soil C. Oxen grazing increased total organic carbon (+ 14%), total nitrogen (+ 12%), carbon/nitrogen ratio (+ 2%), dissolved organic carbon (+ 11%) and dissolved carbon (+ 11%). Available elements and soil bulk density did not change, while soil structure even improved as evidenced by the increase of µWSA (+ 14%) in the oxen-grazed site. This observation is supported by the increase in bacterial abundance (+ 1%) as they are typically present in µWSA, while MWSA and fungal abundance together with microbial biomass remained stable across the two sites. Our findings highlight the potential of combining viticulture with pasture as a strategy to enhance soil health and C, with no evident negative effects. Strengthening the integration and cooperation between viticulture and livestock farming could play a key role in advancing sustainable agriculture for the agroecological transition. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1038/s41598-026-35761-6.

@article{doi101038s41598026357616,
    author = "Fracasso, Ilaria and Timofeeva, Ekaterina and Tiziani, Raphael and Bouaicha, Oussama and Leitinger, Georg and Borruso, Luigimaria and Mimmo, Tanja",
    title = "Five years of oxen grazing enhances soil carbon and structure in alpine vineyards.",
    year = "2026",
    journal = "Scientific reports",
    abstract = "UNLABELLED: Integrating livestock with crop farming can greatly enhance agricultural sustainability and accelerate the agroecological transition. This study investigated the five-year effects of oxen grazing in a vineyard in South-Tyrol (Italy). Grazing occurred from autumn to spring over five consecutive years at a density of 5–7 oxen ha− 1. An adjacent site remained ungrazed. Soil samples were collected and analyzed for soil carbon pools (elemental analyzer), compaction (bulk density), soil structure (micro–water-stable aggregates, µWSA < 63 μm; macro-water-stable-aggregates, MWSA < 250 μm), plant available elements (ICP-MS), total microbial biomass (fumigation and extraction) and microbial abundance (qPCR). The results showed that, despite both fields being pedogenically similar, oxen grazing improved soil C. Oxen grazing increased total organic carbon (+ 14\%), total nitrogen (+ 12\%), carbon/nitrogen ratio (+ 2\%), dissolved organic carbon (+ 11\%) and dissolved carbon (+ 11\%). Available elements and soil bulk density did not change, while soil structure even improved as evidenced by the increase of µWSA (+ 14\%) in the oxen-grazed site. This observation is supported by the increase in bacterial abundance (+ 1\%) as they are typically present in µWSA, while MWSA and fungal abundance together with microbial biomass remained stable across the two sites. Our findings highlight the potential of combining viticulture with pasture as a strategy to enhance soil health and C, with no evident negative effects. Strengthening the integration and cooperation between viticulture and livestock farming could play a key role in advancing sustainable agriculture for the agroecological transition. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1038/s41598-026-35761-6.",
    url = "https://pmc.ncbi.nlm.nih.gov/articles/PMC12901139/",
    doi = "10.1038/s41598-026-35761-6",
    pmcid = "PMC12901139",
    pmid = "41577755"
}

Several large sunspots and red aurorae have been recorded in the literature from relatively low geomagnetic latitude regions in Northeast Asia around 1200-1205 CE, and this interval can be regarded as one of the highest solar activity periods in the Medieval Period. To search for a potential solar proton event during this time and examine the solar cycle dependence, a high-precision carbon-14 analysis with annual resolution was conducted. We found no enhancement in carbon-14 around 1204 CE when prolonged low-latitude aurorae were observed in Kyoto, Japan, as recorded in Meigetsuki. Instead, we found a potential solar proton event in 1200-1201 CE, possibly associated with either the large sunspots or the red auroral events documented in this period. Reconstruction of solar cycles around the event suggested that this solar proton event occurred at the activity cycle's maximum. We also found that the solar cycles around this period were approximately seven to eight years, much shorter than those in the modern era, suggesting extremely high solar activity.

@article{doi102183pjab102011,
    author = "Miyahara, Hiroko and Kataoka, Ryuho and Yamamoto, Kazuaki and Tokanai, Fuyuki and Moriya, Toru and Takeyama, Mirei and Sakurai, Hirohisa and Ohyama, Motonari and Horiuchi, Kazuho and Hotta, Hideyuki",
    title = "Extremely active Sun from 1190 to 1220 in the Medieval Period: Intercomparison of historical records and tree-ring carbon-14.",
    year = "2026",
    journal = "Proceedings of the Japan Academy. Series B, Physical and biological sciences",
    abstract = "Several large sunspots and red aurorae have been recorded in the literature from relatively low geomagnetic latitude regions in Northeast Asia around 1200-1205 CE, and this interval can be regarded as one of the highest solar activity periods in the Medieval Period. To search for a potential solar proton event during this time and examine the solar cycle dependence, a high-precision carbon-14 analysis with annual resolution was conducted. We found no enhancement in carbon-14 around 1204 CE when prolonged low-latitude aurorae were observed in Kyoto, Japan, as recorded in Meigetsuki. Instead, we found a potential solar proton event in 1200-1201 CE, possibly associated with either the large sunspots or the red auroral events documented in this period. Reconstruction of solar cycles around the event suggested that this solar proton event occurred at the activity cycle's maximum. We also found that the solar cycles around this period were approximately seven to eight years, much shorter than those in the modern era, suggesting extremely high solar activity.",
    url = "https://pubmed.ncbi.nlm.nih.gov/41967929/",
    doi = "10.2183/pjab.102.011",
    pmid = "41967929"
}