Director of the Potsdam Institute for Climate Impact Research; Professor for Theoretical Physics at the University of Potsdam; External Professor at the Santa Fe Institute. Heisenberg Scholarship (1989); Extensive research activities abroad, e.g., University of California, Santa Barbara and Santa Cruz; Professor (1989) and later Director at the Center for Marine Environmental Research (ICBM) at the University of Oldenburg; Chair of the Global Change Advisory Group for the 6th EU Research Framework Programme of the EU; Leadership and review activities for numerous international programmes. 2001-05 research Director of the Tyndall Centre for Climate Change Research in Norwich (UK). Since 2005 member of the National Academy of Sciences. (WBGU Member since 1992, 1994–1996 Vice Chair, 1996–2000 Chair, 2004–2008 Vice Chair again, 2009–2016 Chair).