Arctic climate and snow cover trends - Comparing Global Circulation Models with remote sensing observations

摘要

This study assessed the impact of climate change on snow resources in the Arctic. Climate was classified for the period 1950-2100 according to the Koppen-Geiger (KG) classification system using the ensemble average of NASA-NEX CMIP5 projections for the rcp 4.5 scenario. Snow Cover Frequency (SCF) in days/year was calculated from the MODIS10A1 snow product and the SCF trends were calculated across the Arctic for the MODIS period (2001-2016). Ten pollution monitoring areas in the Arctic lowlands, especially vulnerable to climate change impacts, were selected for analyzing the climate and snow regimes. In seven of the ten areas we observed significant changes in the climate during the MODIS period and these same areas also showed the largest SCF trends. At lower latitudes we observed decreasing SCF, while further north, by the shores of the Arctic seas, SCF has increased. Averaged across the Arctic we observed a 0.91 days/year decrease in SCF. Our results show that across the Arctic warmer climate classes have and will continue to replace polar tundra and cold summer regions. Based on the CMIP5 simulations, we expect the coverage of the currently dominant Arctic climate class, Cold climate with cold summers and no dry season (Dfc), to decline by about 40% by 2100 and be replaced by climate classes associated with warm (Dfb, Dsb, Dwb) and hot (Dfa, Dsa, Dwa) summers.