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Vincent Courtillot: The Climate Debate At The French Academy Of Science

On 20 September, the French Academy of Science organised a climate debate that was instigated by the Minister for Higher Education and Research, Mme Valérie Pécresse. This is a short report about the meeting.

The President of the French Academy of Science, Jean Salençon, emphasised from the onset that this meeting was being held in the normal way the Academy operates when asked by government to provide advice on a major topic: a working meeting is first held with those academicians who agree to engage actively in the discussion, together with a number of guests suggested by the academicians themselves or public research organisations such as the National Center for Scientific Research (CNRS). After the debate a short report and recommendations to the government are discussed at a full meeting of the Academy where it can be amended. Then a larger report is produced after a couple of months. The recommendations and the report will be sent to Mme Valérie Pécresse, the Minister for Higher Education and Research, who asked for it, but I assume it will be made public. In that sense, this meeting was not especially ‘secret.’ However, on this particular topic, it was likely on the minds of the Academy advisers that the debate would be scientifically deeper and less passionate if the debating scientists did not have to be concerned about journalists, some of whom may relish in sensationalist reporting of skirmishing and in-house fighting rather than matters of fact.

I believe some 70 academicians attended (out of about 200 members), and there were about 60 guests, mostly scientists engaged in climate research. There were four equal parts in the debate:

1) observations and methods of analysis of these observations;

2) climates of the past;

3) numerical climate models;

4) physico-chemical mechanisms.

In each section, there were 45 minutes of presentations by speakers. Each part was chaired by an academician not involved in climate research. Then two rapporteurs provided their synthesis of the 42 papers that had been submitted via the academy website in response to a call by the organisers (I believe in June). Finally, 3 to 4 scientists involved in climate research could give a short presentation (in principle 7 minutes and 5 slides each). An hour of open discussion followed. Some examples of these short presentations included Serge Planton (from Meteo-France) and myself in part 1 (I summarised our research – with Jean-Louis Le Mouël and Russian colleagues – of the past 3 years on solar signatures in climate observations), Jean Jouzel and Jean-Claude Duplessy on part 2, Richard Lindzen and Hervé Le Treut on part 3, Robert Kandel and Edouard Bard on part 4.

My own assessment of the day was that it was quite well organized by our colleagues Jean-Loup Puget and René Blanchet (an astrophysicist and a geologist who are representing the Academy’s research section on ‘sciences of the universe’). Most presentations were balanced, presented in a quiet and open way. It was very interesting to hear the comments of academicians who were not climate specialists (mathematicians, physicists, chemists, biologists,…), who formed a sort of “educated public” and allowed all to think of how to present this complex science to the more general public. I took 15 pages of notes and heard some very interesting comments and suggestions. There were 4 or 5 rather tense and hostile comments each lasting only a few minutes; overall the day was not (to me) as tense as had been feared or has been suggested afterwards by some journalists.

Although, of course, there was no “vote” at the end of the day, my impression is that half of the attendees balanced in favour of anthropogenic greenhouse gases as the main cause of recent warming (the spatial and temporal signatures of which were discussed), and half in favour of natural causes including the sun. These figures, of course, have a large uncertainty. Even more interestingly, a majority of those leaning towards AGW were quite open to discussion and I believe a main conclusion of the day should be to reaffirm the need that any debate on such a complex scientific question will remain absolutely free, open and tolerant to alternate views, provided of course scientific arguments are used.

Vincent Courtillot is the Director of the Institut de Physique du Globe de Paris and Professor of Geophysics at the Denis-Diderot University. He is a member of the GWPF Academic Advisory Council.