Physical and chemical processes in the Earth’s atmosphere, cryosphere and hydrosphere are the main determiners of climate. Our research focuses on a better understanding of theses processes and on assessing the natural climate variability as well as the anthropogenic impact inflicted. The development in the polar regions is what we are especially interested in. To improve our understanding of the components of the climate system and their interactions, we follow a twofold approach. On the one hand we operate observational and measurement systems for the Arctic and Antarctic, and on the other hand we push the development, optimization and verification of regional and global coupled climate models. We use research vessels, observatories, aircraft and satellite systems for our observations and are concerned with the development of the ocean, atmosphere, sea ice and ice shields. Process studies to assess small-scale phenomena on short time scales go hand in hand with long-term programmes documenting the development of the polar systems.