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Global warming: fluctuating or ending?

Post of the Month: August 2013


Subject:    | Why Is Global Warming Stagnating?
Date:       | 02 Aug 2013
Message-ID: |

Robert Grumbine responds to various climate "questions" including an interview from the english version of Der Spiegel which includes the claim that "[Atmospheric] temperatures haven't risen in nearly 15 years".

Rather than try to thread in to all the various points in the thread, some collection and comment re things which may or may not have been mentioned, but which are common enough.

A couple generalities: does a pretty good job of providing answers to pseudoskeptic 'questions'. is my blog and I am open to questions, at the 'question place' posts, which remain open. Plus I blog about science, particularly climate, particularly the icy end of climate.

On to the thread:
A nice illustration of the difference between the t.o. denizen view and the original poster is given in the 'escalator':

Of course the thermodynamic law is conservation of energy, not conservation of temperature. If more energy is going to the deep ocean, less is staying in the atmosphere. Which means, in temperature, the atmosphere doesn't warm (as much) and the deep ocean warms (more).

Very odd objection to this came up, 'how can the deep ocean warm if the atmosphere (or upper ocean, no matter) isn't?' The deep ocean is ~ 2 C, upper ocean averages ~ 20 C, atmosphere ~ 15 C. The question is not why does the deep ocean warm, it is "why is the deep ocean cold?". Ans:

The usual 'but CO2 is a very rare gas, 400 ppm so it can't have any effect' came up. Properly responded to by analogy to cyanide already. But I'll also point to -- which considers the path a photon has to take through the atmosphere.

And the equally usual 'there's 40,000 ppm water vapor in the atmosphere so CO2 can't matter'. This one ignores the fact that such high concentrations of water vapor can only exist when the atmosphere is exceedingly warm, which is true only of the tropics near the surface of the earth. As you rise in the atmosphere, temperatures -- and water vapor levels -- drop. Such that if you average over the entire volume of the atmosphere, water vapor is only ~2,000 ppm. More of it than CO2 -- on average -- but 5:1, not 50:1. Then consider _where_ the gases are. CO2 is approximately evenly distributed through the atmosphere. Water vapor is trapped towards the surface. In the upper atmosphere -- where terrestrial radiation leaves for space -- there's more CO2 than H2O.

Of course the whole initial thread is based on the absurdity of taking a cherry-picked few years and claiming that this is climate and disproves (whatever the author wants). The idea that you need 20-30 years to define a climate trend is not something made up in the last few months by The Conspiracy. 30 years has been the standard period for climate analyses for over a century. I take a look at some how and why this works in

Somehow, things turn to sea ice, so a few notes:
Arctic sea ice is declining in area, extent, and volume, year-round. The decline is greatest in summer, but still present in winter.

Antarctic sea ice is increasing its winter extents, marginally passing statistical significance (though even this depends on which sources you look at). Interestingly, this was predicted in 1992, and the mechanism confirmed in 2006.

Often confusion is made between Antarctic sea ice and Antarctic ice (period). The continental ice mass is decreasing, which was actually a surprise. Mode of decrease includes substantial melting from the bottom of the ice shelves, where they're in contact with the ocean.

This year's Arctic minimum will probably not break last year's record, so I'm prepared for the inevitable 'arctic ice is recovering' chorus.

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