Markus Rex is the head of atmospheric research at the Alfred Wegener Institute, Helmholtz Centre for Polar and Sea Research, and he is professor for atmospheric physics at the University of Potsdam. He had already joined numerous expeditions to the Arctic, Antarctica and other remote regions of the world to research the complex climatic processes that lead to at times dramatic climate changes. He heads the MOSAiC project, a unique research collaboration by 90 institutions from 20 countries.