1 Potsdam Institute for Climate Impact Research, 14473 Potsdam, Germany; Lamont-Doherty Earth Observatory, Columbia University, New York, NY 10964; Institute of Physics, Potsdam University, 14476 Potsdam, Germany; Anders.levermann@pik-potsdam.de.
2 Potsdam Institute for Climate Impact Research, 14473 Potsdam, Germany;
3 Potsdam Institute for Climate Impact Research, 14473 Potsdam, Germany; Santa Fe Institute, Santa Fe, NM 87501.