The study uses 26 regions with geographical limits shown in Figure 1 and further detailed in Table 1. Their definitions are based on Giorgi et al. 2000 with modifications from the IPCC TAR report (https://www.ipcc.ch/ipccreports/tar/wg1/382.htm) and further refinements, as follows. We reduced Western North America (WNA) to the region south of the Canadian border with predominantly semi-arid climate and defined the remainder plus Alaska as Northwestern North America (NWN). We separated Greenland (GRL) from Northeastern North America (NEN) and defined Canadian Arctic (CAA) as the region north of the polar circle. Likewise, we defined the Eurasian Arctic (EUA) from the parts of Northern Europe (NEU) and Northern Asia (NAS) that lie north of the polar circle. Consistent with the IPCC TAR definition, we split Australia in South Australia (SAU) and North Australia (NAU) and included Antarctica (ANT). We applied minor adjustments to region limits to, for instance, include the Caribbean Islands in Central America (CAM). Giorgi, F. and R. Francisco (2000). Uncertainties in regional climate change prediction: a regional analysis of ensemble simulations with the HADCM2 coupled AOGCM. Climate Dynamics, 16, 169-182. Table 1: Geographical region limits. Regions are enumerated from west to east and north to south. Grid-cells that fall into several region definitions are assigned to a single region (see Figure 1). Cells that are part of East North America (ENA) or Amazon Basin (AMZ) and CAM are assigned to ENA and AMZ, respectively. Cells that are both part of South Asia (SAS) and Southeast Asia (SEA) are assigned to SAS. 1 CAA Canadian Arctic 66N - 90N 170W - 62W 2419234 km2 2 GRL Greenland and Iceland 59N - 85N 62W - 10W 2162335 km2 3 EUA Eurasian Arctic 66N - 90N 10W - 170W 3978506 km2 4 NWN Northwestern North America 50N - 66N 170W - 103W 4426661 km2 5 NEN Northeastern North America 50N - 66N 103W - 50W 3612548 km2 6 NEU Northern Europe 48N - 66N 10W - 40E 4405151 km2 7 NAS North Asia 50N - 66N 40E - 170W 12675758 km2 8 WNA Western North America 30N - 50N 130W - 103W 3236585 km2 9 CNA Central North America 30N - 50N 103W - 85W 3581418 km2 10 ENA Eastern North America 25N - 50N 85W - 50W 2104469 km2 11 MED Mediterranean Basin 30N - 48N 10W - 40E 4901844 km2 12 CAS Central Asia 30N - 50N 40E - 75E 5893624 km2 13 TIB Tibet 30N - 50N 75E - 100E 4479877 km2 14 EAS East Asia 20N - 50N 100E - 145E 6960005 km2 15 CAM Central America 8N - 30N 116W - 60W 2749476 km2 16 SAH Sahara 18N - 30N 20W - 65E 10743390 km2 17 SAS South Asia 5N - 30N 65E - 100E 5244135 km2 18 AMZ Amazon Basin 20S - 13N 82W - 34W 12702471 km2 19 WAF Western Africa 12S - 18N 20W - 22E 7218235 km2 20 EAF Eastern Africa 12S - 18N 22E - 55E 8094930 km2 21 SEA Southeast Asia 11S - 20N 95E - 165E 3932372 km2 22 SSA Southern South America 56S - 20S 76W - 40W 5157699 km2 23 SAF Southern Africa 35S - 12S 10W - 52E 5907629 km2 24 NAU North Australia 28S - 11S 110E - 155E 5106574 km2 25 SAU South Australia 50S - 28S 110E - 155E 2581816 km2 26 ANT Antarctica 90S - 60S 180W - 180E 12826312 km2