Currently, Director, Swiss Federal Institute for Forest, Snow and Landscape Research. Professor Emeritus of Geography, University of Colorado Boulder. Professor, Institute for Atmospheric and Climate Sciences, Swiss Federal Institute of Technology, Zurich. Research studies include climate and cryosphere interaction in polar and alpine regions using ground and satellite measurements as well as climate system modelling. Has led field expeditions to the Greenland ice sheet and other Arctic regions for the past 34 years to measure the dynamic response of ice masses under a warming climate. Has served as Director, Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado; Member, Scientific Advisory Board, Alfred Wegner Institute for Polar Research, Germany; Vice-President, International Commission of Snow and Ice; Chairman, Polar Data Archive Distribution Advisory Group, NASA/EOSDIS. Deeply involved in the assessment of global sea level change and sensitivity studies of large ice sheets. Known for outstanding contributions to science, both through own research and through influence on graduate and post-graduate students. Author and co-author, has published over 131 papers and 14 book chapters, mostly about changes in the Arctic.