Evolutions temporelles de la concentration en gaz à effet de serre et du climat d'après la carotte de Vostok (Antarctique)

Time evolutions of the greenhouse effect gases concentration and the climate from the Vostok core

Laboratoire de Glaciologie et de Géophysique de l'Environnement du CNRS, Associé à l'Université Joseph Fourier, Grenoble

Abstract

Polar ice and air bubbles trapped in it, attest climate history and the atmospheric composition of the Earth. The Vostok drill at the Russian station of Vostok on the Antarctic Plateau provides a more 400 000-year long record of these conditions. Through this time, climate in Antarctica oscillated between 4 glacials, for which surface temperatures were about 10°C below modern ones, and 5 interglacial periods as the modern one. It is shown that greenhouse gases (CO₂ and CH₄) concentrations are higher during warm periods than cold ones. Scrutinising glacial to interglacial transitions shows that Southern Hemisphere processes lead northern ones. Furthermore, sea level rise appears to lag variations of other variables. Finally, these records give evidence that CO₂ and CH₄ levels measured at present time, have never been reached during the late 420 000 years.