Estimates of snow accumulation and volume in the Swiss Alps under changing climatic conditions

Snow is a key feature of mountain environments in terms of the controls it exerts on hydrology, vegetation, and in terms of its economic significance (e.g. for the ski industry). Its quantification in a changing climate is thus important for various environmental and economic impact assessments. Based on observational analysis, surface energy balance modeling, and the latest data from high-resolution regional climate models, this paper investigates the possible changes in snow volume and seasonality in the Swiss Alps. An average warming of 4degreesC as projected for the period 2071-2100 with respect to current climate suggests that snow volume in the Alps may respond by reductions of at least 90% at altitudes close to 1000m, by 50% at 2000m, and 35 % at 3000 m. In addition, the duration of snow cover is sharply reduced in the warmer climate, with a termination of the season 50-60 days earlier at high elevations above 2000-2500 m and 110-130 days earlier at medium elevation sites close to the 1000 m altitude. The shortening of the snow season concerns more the end (spring) rather than the beginning (autumn), so that it should be expected that snow melt will intervene much earlier in the season than under current conditions. The results of this study are of relevance to the estimations of the impacts that the projected warming may have on the amount and timing of water in hydrological basins, on the start of the vegetation season, and on the financial status of many mountain resorts.