Temporal and spatial variations of snow depth in regions of the upper reaches of Yangtze River under future climate change scenarios：A study based on CMIP5 multi-model ensemble projections

Based on multi-model ensemble projections for the period 2011-2040 under climate change scenarios, the temporal and spatial variations of snow depth in regions of the upper reaches of the Yangtze River are investigated in this study. The ensemble projections of future snow conditions are obtained using a coupled modeling approach involving 21 global climate models in the phase 5 of the Coupled Model Intercomparison Project (CMIP5) and the VIC (Variable Infiltration Capacity) model. The climate change scenarios considered include the Representative Concentration Pathways (RCPs) 2.6, 4.5 and 8.5. Results show that both multi-annual and monthly mean temperatures for the next three decades are projected to rise by 1 to 2℃ relative to the base period (from 1970 to 1999), with obvious increase in winter and spring seasons. The average annual precipitation would increase by 3% to 4%, while a slight decrease in autumns and winters. The multi-annual mean snow depth for the next three decades is projected to decrease by about 37.8% relative to the base period. The time of maximum snow accumulation should be similar to that in the base period, while the starting time of snow melting would be slightly lagged behind. For the spatial extent of snow cover, the snow depth in most regions of the upper reaches of the Yangtze River would be reduced, and the reduction could be more than 50% in some areas.