The role of the Bert Bolin Centre is to conduct fundamental research on critical processes in the climate system. The research program embraces natural climate evolution and variability, as well as changes imposed by man´s ever-increasing impact on the climate system through emission of greenhouse gases and aerosols, and changes in land-use, vegetation and hydrology. Our challenge and aim is to provide new knowledge about climate-influencing processes, over a range of time-scales and subsystems.