The objective of the NRP 31 is detailed study of the mechanisms and consequences of future climate changes in the Swiss environment, and the resulting interactions between climate, the water cycle, natural hazards, ecosystems and society. This programme should help improve our understanding of the response of the environment to abrupt short-term climatic events and to long-term climate climate changes, and provide answers to economic and political decision making. The emphasis of research will be on processes acting on the regional scale, especially in the Swiss Alps. Consequences of climate changes on the cryosphere and the hydrosphere are exposed, according to the announced evolution of the parameters temperature and precipitation. NRP 31is an attempt to bring together specific projects in especially sensitive geographical test-zones, as representative as possible of Swiss conditions.