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eeyonkee
Trad climber
Golden, CO
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Topic Author's Original Post - Aug 13, 2007 - 12:13pm PT
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I really don't want to start another free-for-all thread on global warming. I have a specific question based on the (rather long) video that goes with the link, below.
http://video.google.com/videoplay?docid=-3028847519933351566
One of the main contentions of the authors of this video is that historical data show that average temperature lags warming by about 800 years. In other words, it's not excess CO2 emissions that cause global warming but increasing temperature that causes CO2 to rise. An interesting idea that puts the cart before the horse. The authors further contend that sunspot activity is the ultimate global warming culprit and that off-gassing of CO2 in the oceans happens with increasing global temperatures (and is primarily responsible for the strong correlation).
I would like to know if the data truly support such a supposition. My gut feeling is that the data cannot be resolved to 800 years, but I don't really know. Any information on this would be greatly appreciated.
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Chiloe
Trad climber
Lee, NH
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Aug 13, 2007 - 01:13pm PT
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Greg, here's a good description of the actual science behind this question. It's been raised many times as a "favorite contrarian talking point," but patient explanations like the one linked below just bounce off them.
(My) short version of the answer: in modern times, anthropogenic CO2 leads and appears largely to be driving the temperature increase. In prehistoric times without anthropogenic CO2 the relation is more complicated: when the temperatures begin to rise for any reason, through several mechanisms the warming tended to increase CO2 which further increases temperature -- it's a positive feedback in which both are rising. Examples of such positive feedbacks that could kick in to accelerate global warming in the near future include melting Arctic Ocean ice which will make a big chunk of Earth darker and more solar-heat-absorbing; or thawing of permafrost areas in which much CO2 is presently sequestered.
But for a longer, more careful answer, listen to the experts:
http://www.realclimate.org/index.php/archives/2007/04/the-lag-between-temp-and-co2/
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eeyonkee
Trad climber
Golden, CO
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Topic Author's Reply - Aug 13, 2007 - 01:54pm PT
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Thanks, Chiloe. This is just the kind of link I was hoping for.
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eeyonkee
Trad climber
Golden, CO
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Topic Author's Reply - Aug 13, 2007 - 02:48pm PT
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You must be quite an expert on this subject to characterize those holding dissenting opinions as whackjobs, weschrist.
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Hawkeye
climber
State of Mine
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Aug 13, 2007 - 03:39pm PT
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weschrist is for sure an expert. by gawd he is a college boy, aint that enuff?
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TradIsGood
Happy and Healthy climber
the Gunks end of the country
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Aug 13, 2007 - 03:50pm PT
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Then consider that the real answer is "it depends...".
Certainly the positive feedback in the past did not last forever or we would not be considering this problem.
Nor do we know what the future will bring. It is fairly clear that some things about the earth are cyclic, and others are not.
For example, seasons are cyclic and distribution of species and even chemicals and isotopes are for the most part not. The planet is a great big non-linear "system" with lots of variables whose dependencies are not all well understood.
Raise the CO2 level high enough and the planet will not support combustion, or animal respiration, and lots of things will change. (Interesting question. Could we do that ourselves?)
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