Climat et atmosphère au Quaternaire : de nouveaux carottages glaciaires

Over the last 20 years, studies of Antarctic and Greenland ice cores have provided a wealth of information directly relevant to the past and to the future evolution of our climate with, as more important, the discovery of a link between greenhouse gases and climate in the past and the characterization of rapid climate changes. These results are based on the analysis of deep ice cores such as the one drilled at the Vostok site, which allows us to describe the evolution of Antarctic climate and of atmospheric composition over 420 ka (thousands of years), and GRIP and GISP2 (Greenland), which precisely depict the rhythm of rapid changes during the last 100 ka. Information available from ice cores has considerably increased in 2004 thanks to the EPICA Dome C ice core in Antarctica and to the North GRIP one, in Greenland. We present these two successful international programs and describe the first results they have provided, with the EPICA Dome C core covering eight climatic cycles (800 ka) and the North GRIP one allowing us to reach, for the first time from a northern-hemisphere ice core, the Eemian, the warmest past of the last interglacial around 120 ka ago.