Prof Dr Hermann Held has been Professor of Sustainability and Global Change at the University of Hamburg and Head of the related Research Unit since 2010. He has been member of Hamburg’s successive Clusters of Excellence on Climate, CliSAP and CLICCS since 2011. He acted as Lead Author in the Working Group on Mitigation for the IPCC’s (Intergovernmental Panel on Climate Change) Fifth Assessment Report. Currently he is acting as Review Editor for the IPCC and as Editor for the academic journal Earth System Dynamics. Hermann Held holds a doctoral degree in Physics from the University of Munich. He worked on the climate problem at the Potsdam Institute of Climate Impact Research (PIK) from 1999 to 2010, first as PostDoc, then as Junior Research Group Leader, and finally as Department CoChair, together with Ottmar Edenhofer. From 2005-2009 he acted as President of the European Geoscience Union’s Division ‘Energy, Resources, and the Environment’.