Swindled!

By William and Gavin

On Thursday March 8th, the UK TV Channel 4 aired a programme titled “The Great Global Warming Swindle”. We were hoping for important revelations and final proof that we have all been hornswoggled by the climate Illuminati, but it just repeated the usual specious claims we hear all the time. We feel swindled. Indeed we are not the only ones: Carl Wunsch (who was a surprise addition to the cast) was apparently misled into thinking this was going to be a balanced look at the issues (the producers have a history of doing this), but who found himself put into a very different context indeed [Update: a full letter from Wunsch appears as comment 109 on this post]

So what did they have to say for themselves?

CO2 doesn’t match the temperature record over the 20th C. True but not relevant, because it isn’t supposed to. The programme spent a long time agonising over what they presented as a sharp temperature fall for 4 decades from 1940 to 1980 (incidentally their graph looks rather odd and may have been carefully selected; on a more usual (and sourced!) plot the “4 decades of cooling” is rather less evident). They presented this as a major flaw in the theory, which is deeply deceptive, because as they and their interviewees must know, the 40-70 cooling type period is readily explained, in that the GCMs are quite happy to reproduce it, as largely caused by sulphate aerosols. See this for a wiki-pic, for example; or (all together now) the IPCC TAR SPM fig 4; or more up-to-date AR4 fig 4. So… they are lying to us by omission.

The troposphere should warm faster than the sfc, say the models and basic theory. As indeed it does – unless you’re wedded to the multiply-corrected Spencer+Christy version of the MSU series. Christy (naturally enough) features in this section, though he seems to have forgotten the US CCSP report, and the executive summary which he authored says Previously reported discrepancies between the amount of warming near the surface and higher in the atmosphere have been used to challenge the reliability of climate models and the reality of human induced global warming. Specifically, surface data showed substantial global-average warming, while early versions of satellite and radiosonde data showed little or no warming above the surface. This significant discrepancy no longer exists because errors in the satellite and radiosonde data have been identified and corrected. New data sets have also been developed that do not show such discrepancies. See-also previous RC posts.

Temperature leads CO2 by 800 years in the ice cores. Not quite as true as they said, but basically correct; however they misinterpret it. The way they said this you would have thought that T and CO2 are anti-correlated; but if you overlay the full 400/800 kyr of ice core record, you can’t even see the lag because its so small. The correct interpretation of this is well known: that there is a T-CO2 feedback: see RC again for more.

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