Recent snow cover variations and avalanche activities in the Southern Alps

Snow and albedo play a significant role in the planet's radiation balance. Snow cover extension, of the Northern Hemisphere in the last forty years, generally decreased causing direct and indirect feedback both on climate and atmospheric circulation. Up-to-date available data on seasonal snow cover trend are scarce and limited to few nations. Few European studies in the Northern Alps highlighted a decrease in snow cover duration and an increase of its elevation for tourism purposes. Using the data of more than 60 sites located in the Southern Alps a first budget of the recent snow cover trend has been outlined. Compared to the 1961-90 mean value, the average snow cover duration decreased of about 14 days, with a major influence on elevations lower than 1600 metres. Seasonal snow precipitation accumulation has been decreasing, at all elevations, since 1990. Winter 2008-2009 was the 3(rd) or 4(th) more snowy season since 1930. During this winter spontaneous avalanche activity was frequent and extreme avalanches often detached. The 2008-2009 winter daily observation data of several sites located in the Southern Alps were used to find interconnections between recent snow cover variations, spontaneous avalanche activity and avalanche accidents.