1. IIASA−International Institute for Applied Systems Analysis, Schlossplatz
1, 2361 Laxenburg, Austria
2. CICERO−Center for International Climate and Environmental Research−Oslo, P.O. Box 1129, Blindern, 0318 Oslo, Norway
3. Department of Geosciences, University of Oslo, P.O. Box 1022 Blindern, 0315 Oslo,
Norway