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, since 2009 Chair .