Pioneer of glaciology, legendary hero of the first wintering carried out in Antarctica in 1957, central man in the advance of science on the question of global warming, and as such, the only Frenchman to have received the prestigious Blue Planet Prize – a sort of prize Nobel for the environment – in 2008, in Tokyo, Claude Lorius died on Tuesday March 21 at the age of 91.
History, which loves anecdotes and venerates myths, will undoubtedly remember from its life that of a formidable intuition: one day in 1965, near the Dumont d’Urville base in Adélie Land (the part of Antarctica claimed by France), on the evening of a failed day of coring, he drinks a glass of whiskey with an Australian researcher, Bill Budd. The glaciologists, who pierce the ice cap to the depths, deduce from the analysis of the chemical composition of these cores the climate which reigned on Earth in remote times (the further down one goes in the layer of ice, the more it corresponds to distant ages).
Anyone who has ever put such an ice cube in his glass knows that the air, which is very compressed, gives off a fizz that makes his whiskey look like champagne. Looking at these bubbles, Claude Lorius said to himself: but if we could extract and analyze the air contained in the ice, we would have the archives of the atmosphere there.
The idea is at the origin of everything we know today in climatology. And in particular that the climate change we are witnessing is of anthropogenic origin: the clever word to say that we humans are responsible for it.
Temperature and carbon dioxide
But it will be twenty years before the glaciologist’s intuition produces these unexpected conclusions. Because it will take all the force of conviction of Claude Lorius to push the Americans (who have the planes) to fetch the carrots from the Soviets (who have the deepest boreholes) at the Vostok station to bring them back to France, where the teams from the Grenoble laboratory, which he founded, and those of climatologist Jean Jouzel, at the Ecole polytechnique, have developed a technique for analyzing the air trapped in the ice.
And there, the amazed and incredulous eyes of the researchers see two curves taking shape: that of the temperature on the surface of the Earth over thousands of years and that of the carbon dioxide content. The two curves are strictly parallel. Eureka!, as the other said.
These are the two famous curves that the former American vice-president Al Gore, taking up his stick as an environmental marshal, has shown almost everywhere since the beginning of the 2000s. If industrial civilization produces more and more greenhouse gas greenhouse, the climate, as the history of the Earth written in the ice tells us, will continue to heat up, following an exponential acceleration.
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