he was one of the first to establish the role of carbon dioxide in global warming.

By reconstructing the climates of the past from ice cores, Claude Lorius, whose death we learned on Thursday March 23 at the age of 91, was one of the first to establish the role of carbon dioxide in the global warming. As early as the 1960s, Claude Lorius became interested in the air bubbles that are trapped in the deepest, and therefore very old, ice cores. He very quickly had the intuition that these were tiny samples of the atmosphere of the past. By analyzing these air bubbles and the surrounding ice, it was possible to reconstruct both the evolution of temperatures and the presence of greenhouse gases in the atmosphere at the same time. This is how in the 1980s, Claude Lorius, Jean Jouzel and their teams, by studying ice found up to two kilometers deep in Antarctica, managed to reconstruct the history of the relationship between greenhouse gases greenhouse and the temperature at the surface of the earth over 160,000 years and they were able to observe an unprecedented and parallel rise in the curves of CO2 and temperature after the industrial revolution.

Climate of the past and that of the future are linked

The analysis of very deep ice has already made it possible to establish a relationship between climate and greenhouse effect over the last 800,000 years. With even deeper boreholes, in the ice in Antarctica, scientists hope to go back a million years. And then, to reconstruct the climate beyond a million years, it is also possible to study cores of sediments accumulated in the seabed. This is another analysis technique, but it allows us to go back even further in time.

Climate of the past and that of the future are linked, because to simulate the climate of the future, it is necessary to build mathematical models and since we are heading towards large-amplitude temperature and climate changes, in connection with greenhouse gas emissions new greenhouses, due to human activities, it is necessary to be able to study how our planet behaved during the major climatic changes of the past. Understanding the interactions between the atmosphere, CO2, temperatures and the oceans in the distant past thus allows us to test the validity of forecasting models for the future.