Natural climate forcing: volcanism and solar

The cause of the natural climatic variability over the last 2000 years are poorly known. Among the possible causes, the solar activity and the volcanic activities are the possible candidats of external forcing. We propose to analyse 10Be, a tracer of solar activity, as well as stable isotopes of sulphur and oxygen of sulfate, tracers of the of the Plinian type volcanic activity. These isotopic compositions will be extensively studied in ice cores from complementary Antarctic sites.