The august French Academy has spoken. After a cursory examination of the climate issue, a day of selected testimonies, and some internal discussion among admitted non-experts, their Oct. 28 report to the French science minister concluded that global warming is "real and anthropogenic." Too bad; this report will remain as a stain on the Academy's reputation for years to come --once the true scientific facts gain acceptance.
How could the Academy reach such a conclusion? Simply by ignoring any contrary evidence -- all published in peer-reviewed journals and readily available. So another interesting question is: Why did they ignore contrary evidence? For the answer, we must turn to psychologists or sociologists. On the other hand, the French Academy should be praised for organizing a debate on climate, however imperfect. I cannot imagine that the U.S. National Academy would even consider such an idea.
The global climate indeed warmed between 1910 and 1940, but due to natural causes, and at a time when the level of atmospheric greenhouse gases was quite low. There is little dispute about the reality of this rise in temperature and about the subsequent cooling from 1940 to 1975, which was also seen in proxy records (such as ice cores, tree rings, etc.) independent of thermometers. The Academy, following the U.N.-supported IPCC, then reports a sudden climate jump around 1977-1978, followed by a steady increase in temperature until at least 1997. It is this steady increase that is in doubt; it cannot be seen in the proxy records.
Even more important, weather satellite data, which furnish the best global temperature data for the atmosphere, show essentially no warming between 1979 and 1997. Now, according to well-established theories of the atmosphere as expounded by textbooks, the surface warming must be smaller than the atmospheric trend by roughly a factor of two. But one half of zero is still zero. It suggests that the surface warming reported by the IPCC, based on weather-station data that had been processed by the Climate Research Unit of East Anglia University (CRU-EAU) may not exist. How could this have come about? We will get the answer once we learn how the CRU selected particular weather stations (from some thousands worldwide) to use for their global product and how they then corrected the actual data (to remove urban influences and other effects). So far, none of the several investigations of "Climategate" has delved into these all-important details. Nor have they established the exact nature of the "trick" used by the CRU and fellow conspirators to "hide the decline" (of temperature) -- referred to in the leaked Climategate e-mails.
The disparity between surface trends and atmospheric data as measured by satellites (and independently also by radiosondes in weather balloons) has been known for more than a decade. Yet it has been steadfastly ignored by the IPCC's Summary for Policymakers and also by the French Academy. Evidently, it is not a subject they wish to discuss. In my book, Hot Talk, Cold Science, published in 1997, I show a graph that clearly delineates the difference between surface and atmospheric trends in the tropical region. In 2000, the National Research Council of the National Academy of Sciences even published a study called "Reconciling Observations of Global Temperature Change"; they tried to account for the discrepancy between atmospheric and surface trends (between 1979 and 1997) and concluded that they could not. A federal report of 2006 by the Climate Change Science Program (CCSP-SAP-1.1) shows again the same disparity. Yet an obvious way to solve the puzzle is to conclude that the surface trends are vastly exaggerated and may even be close to zero.
Of course, it is also necessary to deal with sea surface temperatures, since oceans cover 71% of the earth's surface. An analysis of the available data shows again no appreciable warming trend after appropriate corrections have been made. As suggested in studies published in 2005, the reported warming trend of SST may be based on an artifact and is not real. So it becomes clear that the French Academy's conclusion (that global warming is "real and anthropogenic") does not accord with observed facts.
An obvious question is why these facts were not publicized earlier. I can say only that any such claim of "no global warming in the 1980s and 1990s" would have been shouted down and discounted by the scientific community and the public. However, "Climategate" and the subsequent discovery of many errors and shortcomings by the IPCC have changed the situation drastically. It is now quite alright to express what might have been considered heretical opinions.