1 Fondazione Eni Enrico Mattei, 30124 Venice, Italy. Ca' Foscari University of Venice, 30123 Venice, Italy.
2 Mercator Research Institute on Global Commons and Climate Change, 10829 Berlin, Germany. Potsdam Institute for Climate Research, 14473 Potsdam, Germany. Technische Universität Berlin, 10623 Berlin, Germany. ottmar.edenhofer@pik-potsdam.de.
3 Mercator Research Institute on Global Commons and Climate Change, 10829 Berlin, Germany. Hertie School of Governance, 10117 Berlin, Germany.