Claude Allègre: The Climate Imposter

  • The first thing one might notice is that almost every non-french scientist has their name spelled wrong: Solansky for Sami Solanki; Usoskiev for Ilya Usoskin and Funkel for Richard Finkel. The most amusing case is during the discussion of tropical cyclones with climate change, where he lists three names of people who have posited a connection: “Wester, Tech and Kerry Emmanuel”. Everyone of course recognizes Kerry Emanuel (despite the incorrect spelling), and “Wester” is (also misspelled) Peter Webster (of Webster et al, 2006). But who was this eminent Hurricane expert Tech? I had no idea until Stephane Foucart lifted the veil. Peter Webster is from the Georgia Institute of Technology, frequently abbreviated to simply “Georgia Tech”. So in his “extensive literature studies” Allègre probably found a line like “Peter Webster, Georgia Tech, thinks that …” and voila! Professor Tech was born!
  • On page 53, in a typical example of his style, Allegre writes that
    ”Jones declares that the global mean temperature raised by 0.6% [sic]. …. How can he claim such a precision with such sampling errors? Nevertheless, Hansen-the-fanatic, without revealing his sources, immediately approves of Jones curve. Those who made statistics based on such shortcomings in sampling are discredited as scientists”.
    Wow. We’re pretty sure that most people measure temperature deviations in degrees, so maybe the ‘%’ was just a simple typo. The characterisation of Hansen is presumably hyperbole (though see below for worse treatment), but given that all of the sources of the GISTEMP temperature record (which was first published in 1987) are available online (along with all the source code, and completely independent replication), the ‘without revealing his sources’ line is a little rich (especially given Allègre’s undocumented ‘extrapolation’ (cough) of the Grudd data series mentioned above.
  • On page 300, the greenhouse effect is explained, but for some reason CO2 is not considered to be a ‘real’ greenhouse gas. He says explicitly there are three such gases, water vapour, carbon dioxide and methane (This is a pretty large simplification since it neglects ozone, N2O, any number of CFCs, and theoretically pretty much any gas with a structure that has three or more atoms). He continues:
    ”It is due to water vapour, and water vapour alone, that the mean temperature at the Earth surface is +15°C and not -18°C”.
    This again is plain wrong. Depending a bit how you weight the overlapping spectral absorptions of the different greenhouse gases the contribution of CO2 to the total greenhouse effect is about 20% (with water vapour giving 50% and 25% for clouds, which we are sure that Allègre realises are made of condensate (liquid water and ice) and not vapour…). And indeed, since water vapour in particular is a feedback to the temperatures, removal of CO2 will certainly lead to cooling and a subsequent reduction in water vapour.
  • Unsurprisingly, Allègre is of course very sceptical about the use of computer models, and thinks they are taking up all the money available for research (an error that would be easily corrected by looking at NASA’s budget for instance) and so his preference for ‘true’ observations is clear. Take the last interglacial period for instance (also known as the Eemian), around 125,000 years ago. He compares (see figure above) something called the “Gore curve” with something called the “true curve” (la courbe veritable). Al Gore actually shows the temperature and CO2 evolution from Epica Dome C for the last 600.000 years. So let’s assume that this is in fact what Allègre means. Amusingly, this image from the movie shows that Allègre’s hand drawn version of the bottom curve (the reconstructed temperature in East Antarctica) is profoundly different (in the relative warmth at the Eemian, and the number of cycles), but let’s move on… Skipping past the inconsistency in the text where he says that until now the best estimate for the last interglacial temperature in Antarctica was +3°C (compared to present) while his “Gore curve” has a zero anomaly compared to today, let’s look at the justification for the new ‘true’ estimate of +6°C warmer. This is referenced to a paper by Sine et al, 2007 in Science (note that every piece of that reference is wrong: as usual, the name is misspelled (it’s Louise Sime, not Sine), the year was 2009 and the publication was in Nature – easy mistakes, I guess). Ice core temperature reconstructions such as Dome C are based on the isotopic composition of the ice. This isotope signal needs careful calibration and Louise Sime and colleagues make the point that under warm climate conditions such as the Eemian the calibration developed for cold climate conditions might be different – in fact isotopes during warm periods might be less sensitive to temperature, and so applying the cold-climate calibration might underestimate actual temperatures. However, their results would therefore only concern the time period at the peak of the ultimate interglacial, and does not have any implications for the cold climate values. Note however, that Allègre’s ‘one true curve’ seems to have had a warm trend imposed from 125,000 years ago to the present. I contacted Louise Sime and asked if she thought this was a good use of her paper. She made it clear that she’d not had any exchange with Claude Allègre and that her paper does not discuss the temperature reconstruction over the entire glacial-interglacial period at all (that would be a ‘no’). In summary, Allègre presents a ‘true curve’ which is hand-drawn, in which an Antarctic temperature record is described as a global mean, on which he imposes a long term trend which is credited to Sime and colleagues who completely disown it. And the irony of ironies? Sime’s results are based on a climate model.
  • The phase relation between CO2 and temperatures in the Antarctic ice cores is a frequent source of confusion, and Allègre doesn’t attempt to miss this opportunity to confuse further. As is well known, both temperature and CO2 are correlated to the Milankovitch cycles in complex ways – with both climate acting on the carbon cycle and with the CO2 level changing climate through it’s role as a greenhouse gas. The changes over time have been described as a “chicken and egg” situation in which changes in one component affect the other – however the first one was changed initially (Lorius et al, 1990). Thus the leads and lags involved doesn’t have any impact on climate sensitivity calculations, but it is important for understanding carbon cycle feedbacks which might affect future concentrations of CO2. Allègre makes the standard (and illogical) contrarian argument that if eggs follow chickens then chickens cannot follow eggs, and highlights the paper by Caillon et al, 2003 that constrained the CO2 lag to about 800 years (though with large uncertainties) based on work from his PhD. According to Allègre, Caillon was then ‘punished’ by his institute (which is mine too) for publishing this paper. So I called Nicolas to ask about this ‘punishment’. Once he stopped laughing, he pointed out that he is doing exactly what he wants to be doing (developing measuring technologies) and is very happy with his permanent (tenured) position at CNRS. I’m sure more people would love to be punished like that!
  • It is a very common technique in debating to try and suggest that your argument is correct by claiming that more and more important people are agreeing with it. Allègre makes frequent use of this tactic, but Sylvestre Huet made the effort to call some of these alleged “heretics” and “insurgents” and found that they didn’t agreed with Allègre’s position at all. Allègre additionally claims (p138) that there is even numerical proof for this reversal in the opinion among “american specialists of climate”. However, the source for this claim was a 2009 survey among American TV weather presenters. In a further effort to round up some support, he cites Bill Ruddiman’s hypothesis that human land use change was an important climate forcing over the last few thousand years. But Ruddiman’s theory works via the influence of prehistoric man on the global methane and carbon cycle and needs their greenhouse effects to work! [RC note: Allègre isn't the only contrarian to have mistakenly dragooned Ruddiman to their cause - see this earlier example!]

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