Re: [asa] Claude Allegre, one of France's leading socialists

From: PvM <>
Date: Tue Mar 06 2007 - 12:43:10 EST

Claude Allegre is an interesting case, yet it seems that his arguments
are as poorly supported by science and are based mostly on a
misunderstanding of scientific research (mostly outside his realm of
academic knowledge).

As is explained on Realclimate in a guest commentary by Georg Hoffmann

Con Allègre, ma non troppo

Guest Commentary by Georg Hoffmann (LSCE)

Climate change denial is not necessarily a speciality of Washington DC
think tanks - sometimes it can also be found in old Europe. Right now
there is a little media storm passing by in France evoked by an
article from Claude Allègre in L'Express. Who is Claude Allègre? He is
one of the most decorated french geophysicists specializing in
geochemistry and the use of paleomagnetism. Being a longtime friend of
the former prime minister, Lionel Jospin, he even became Minister of
Education and Research in the former Socialist government. He still
plays an active role within the Socialist party and though he has
never published anything directly related to anthropogenic climate
change, one would assume that he has some understanding of the
scientific matter. But this assumption would be wrong.

In the French weekly journal l'Express he exposed his "sceptical"
views in an article entitled "The snows of Kilimanjaro". In the short
editorial, he somehow became lost when following Ernest Hemingway to
East Africa. Allègre mentions two scientific examples to demonstrate
that there is something fundamentally wrong in the IPCC statements on
the reality of climate change. First, he commented on the disappearing
glaciers of the Kilimanjaro, sometimes treated as the "Panda" of
anthropogenic climate change. Citing a "Nature" study (which was in
fact published in Science) by Pierre Sepulchre and colleagues from my
laboratory, he claimed that this modelling study demonstrated that
Kilimanjaro's glaciers are controlled by tectonic activity. In fact,
the article describes the impact of tectonics of the East African
Highlands on Indian ocean moisture transport ---- on a time scale of
millions of years! This confuses glacier variability over the last
~100 years with rainfall trends extending back to the time of the
early hominids (such as Lucy).

In fact, there are good reasons to believe that the situation on the
Kilimanjaro is a bit more complicated than a simple "atmosphere gets
warmer/ glaciers are melting" equation (for instance, see this
previous post on tropical glacier retreat). Furthermore, the real link
to climate change does not come from the retreat of one single
tropical glacier, but from the fact that, to my knowledge, all studied
tropical glaciers have retreated over the 20th century, and the
retreat rates have generally increased in recent decades.

Allègre's misunderstanding was immediately followed by another one.
Citing a recent study on relatively stable Antarctic snowfall over the
last 30 years (Monaghan et al, 2006, discussed here) , he highlighted
what he thought was a clear contradiction to future climate
simulations of global circulation models (melting of the Antarctic ice
sheet). However, that's not what they predict. All models predict a
comparably stable Antarctic ice sheet for the 21th century in which
comparably moderate temperature changes in Antarctica are compensated
by slight increase in snowfall. The Monaghan et al study does not
contradict these model scenarios.

The French climate research community was of course not very pleased
about this short sequence of misrepresentations and personal attacks
("les Cassandres") and corrected Allègre in an open letter published
here on the website of the Institute Pierre Simon Laplace (which
includes links to the ongoing back and forth, for those that speak

Curiously enough, twenty years ago Allègre wrote in "Clés pour la
géologie", (éd. Belin/France Culture):

     "En brûlant des combustibles fossiles, l'homme a augmenté le taux
de gaz carbonique dans l'atmosphère, ce qui fait, par exemple, que
depuis un siècle la température moyenne du globe a augmenté d'un

     "By burning fossil fuels man enhanced the concentration of carbon
dioxide in the atmosphere which has raised the global mean temperature
by half a degree in the last century".

But at that time he used this argument against the anti-nuclear energy
movement. It might be that there is simply a bit too much politics in
Allègre's life...


In short, Allegre's objections to the Kilimanjaro as well as the
Antarctic seem to be based on a misunderstanding on his part of the
science involved. The increase in precipitation in the Antarctic is
indeed a prediction of the global circulation models.

If there are other objections Allegre has raised then I will surely
look into them in more detail.

It is sad that Allegre's testimony was used by government officials in
charge of policy while little attention was given to the science
behind global warming.
Hopefully that will change now.

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Received on Fri Mar 9 13:40:15 2007

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