Claude Allègre: The Climate Imposter

Guest Commentary by Georg Hoffmann

In mathematical proofs, it’s a well-known fact that if at some point you divide by zero accidentally or on purpose, then you end up being able to prove absolutely anything you want – for instance, that 2+2=5 or that 1+1=0. The same phenomena appears to govern any number of publications that conclude that climate science is all a fraud – at some point, an impossible calculation is performed and from then on, anything (and everything) can be proven. Critical thinking appears to vanish.

The latest example is that of Claude Allègre – whose recent book “The climate imposture” would have you believe at least six impossible things before breakfast and a great many more before dinner. This is notable because Allègre is one of the most eminent figures in science communication in France, Academie de Sciences member, Crafoord prize winner, former minister of education and research and a fixture on the late night talk shows in France (including a topical satirical version of the ‘muppets’). One might expect a certain degree of rigour from an author with such a pedigree, but on the contrary, nearly every explanation, graphic, or citation in this book is misleading or just plain wrong. If Allègre was not such a high profile figure in France, this nonsense would have been dismissed and ignored, instead, it is regular fodder for the late night talk shows. In my entire career I have never seen so many factual errors in a single publication. It is truly a remarkable work!

It is practically impossible to give a complete overview of what is wrong with the Allègre’s book. However, some people have made a good start: Stephane Foucart, a science journalist at Le Monde, wrote a piece on Le cent-fautes de Claude Allegre (the ‘Hundred Errors’ – this is a play on words, ‘un sans-faute’ (pronounced the same way) means a perfect score) and Sylvestre Huet from the Liberation started a series of debunkings and is now at part five (also in French) and which he has turned into a short book! I started my own list of errors here (in German).

One of the more egregious examples of blatant making stuff up was covered by Science last week (following on from a post by Huet who revealed that Allègre had hand-drawn a continuation of tree-ring data from Hakan Grudd to show cooling over the 21st Century – something of course that no trees could possibly show (at least yet!). Even before Allegre “improved” the data by drawing in an extension more to his liking, the implication that Grudd’s work in any way challenges the prevailing view of unusual large scale warming in recent years was highly misleading. Grudd’s paper (available here, open access) deals solely with summer temperatures at Lake Tornetrask in Northern Sweden, and the paper states clearly that “although the climate of northern Fennoscandia seems to have been significantly warmer during medieval times as compared to the late-twentieth century, the published composite records of northern hemisphere climate (Moberg et al. 2005) do not show a conspicuously warm period around AD 1000.” Once again, Allègre has shown himself willing to jump on any curve “going my way,” regardless of its relevance.

But much of the joy of reading this book is in details – things that it would be trivial to get right without having much impact on the general thesis being put forward, but instead reveal without doubt that the author does not have a single clue about the subject. So let’s start (all translations are mine and reasonably accurate):

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