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The issues Crichton raises are familiar to those of us in the field, and come up often in discussions. Some are real and well appreciated while some are red herrings and are used to confuse rather than enlighten.
The first set of comments relate to the attribution of the recent warming trend to increasing CO2. One character suggests that “if CO2 didn’t cause the global cooling between 1940 and 1970, how can you be sure it is responsible for the recent warming?” (paraphrased from p86) . Northern Hemisphere mean temperatures do appear to have cooled over that period, and that contrasts with a continuing increase in CO2, which if all else had been equal, should have led to warming. But were all things equal? Actually no. In the real world, there is both internal variability and other factors that affect climate (i.e. other than CO2). Some of those other forcings (sulphate and nitrate aerosols, land use changes, solar irradiance, volcanic aerosols, for instance) can cause cooling. Matching up the real world with what we might expect to have happened depends on including ALL of the forcings (as best as we can). Even then any discrepancy might be due to internal variability (related principally to the ocean on multi-decadal time scales). Our current ‘best guess’ is that the global mean changes in temperature (including the 1940-1970 cooling) are actually quite closely related to the forcings. Regional patterns of change appear to be linked more closely to internal variability (particularly the 1930’s warming in the North Atlantic). However, in no case has anyone managed to show that the recent warming can be matched without the increases in CO2 (and other GHGs like CH4).
Secondly, through the copious use of station weather data, a number of single station records with long term cooling trends are shown. In particular, the characters visit Punta Arenas (at the tip of South America), where (very pleasingly to my host institution) they have the GISTEMP station record posted on the wall which shows a long-term cooling trend (although slight warming since the 1970’s). “There’s your global warming” one of the good guys declares. I have to disagree. Global warming is defined by the global mean surface temperature. It does not imply that the whole globe is warming uniformly (which of course it isn’t). (But that doesn’t stop one character later on (p381) declaring that “..it’s effect is presumably the same everywhere in the world. That’s why it’s called global warming"). Had the characters visited the nearby station of Santa Barbara Aeropuerto, the poster on the wall would have shown a positive trend. Would that have been proof of global warming? No. Only by amalgamating all of the records we have (after correcting for known problems, such as discussed below) can we have an idea what the regional, hemispheric or global means are doing. That is what is meant by global warming.
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Another issue that often comes up in discussion about the surface temperature record is the impact of the Urban Heat Island Effect (UHIE), and here it appears on p370. It is undisputed that the centres of cities such as New York are significantly warmer than the surrounding countryside. This issue has been extensively studied and is corrected for in all analyses of the global temperature trends. To see whether there might still be a residual effect in the corrected data, a recent paper (Parker, Nature, 2004) looked at the differences in the trends if you looked separately at windy and not-so-windy conditions. Wind is known to diminish the impact of urban heating, and so the trends on windy days should be less than trends on still days if this was important. The trends actually end up almost exactly the same. Other validating data for the corrected surface temperature record comes from the oceans, which have also been warming in recent decades. Even Richard Lindzen , normally an arch-skeptic on these issues, stated that “ocean temperature increases present some support for the surface temperature record” Lindzen (2002). Another demonstration that the corrections are sufficient is that over the continental US, where many cities have a clear urban heating signal, the mean of the corrected data is actually rather flat (p88) - i.e. none of the strong urban biases in the US has made it into the regional or indeed global mean.
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Finally, in an appendix, Crichton uses a rather curious train of logic to compare global warming to the 19th Century eugenics movement. He argues, that since eugenics was studied in prestigious universities and supported by charitable foundations, and now, so is global warming, they must somehow be related. Presumably, the author doesn’t actually believe that foundation-supported academic research ipso facto is evil and mis-guided, but that is an impression that is left. In summary, I am a little disappointed, not least because while researching this book, Crichton actually visited our lab and discussed some of these issues with me and a few of my colleagues. I guess we didn’t do a very good job. Judging from his reading list, the rather dry prose of the IPCC reports did not match up to the some of the racier contrarian texts. Had RealClimate been up and running a few years back, maybe it would’ve all worked out differently…"
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http://www.realclimate.org/index.php?p=74
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