Paraglacial slope instabilities in relation with glacier retreat: the case of Venosta Valley (Italy)

In the context of climate change, glaciers in the Alps are rapidly receding. Different studies suggest that in this epoch they are out of balance with the climate, and that glacier retreat rates have exceeded their historical precedents of the early 21st century. Mountain glaciers are important resources for our society because they provide different ecosystem services; climate change is threatening the stability of these benefits and by effect of permafrost thaw and post-glacial debuttressing, it is causing the emergence of climate-related hazards at high altitude.To understand how mountain slopes are reacting to deglaciation, we compiled the first inventory of paraglacial slope instability phenomena occurred on glaciers of the Venosta Valley (Italy) since the little ice age. We reconstructed their geographical distribution, their relationship with the deglaciation and we studied their runout to assess possible implication of such events on alpine routes.To better quantify deglaciation, we also digitized the glaciers outlines based on imagery from 2020, updating the archives and providing useful data for comparisons with previous studies. Up to 2020 it is possible to identify a total of 500 slope instability events occurred within a region that since the LIA suffered a strong glacier area contraction (-69.44%). This research testifies how the mountains are rapidly reacting to climate change and deglaciation, highlighting that alpine routes crossing the glaciers of our study region cannot be considered outside the potential runout zone of a rockfall.it is possible to identify a total of 500 slope instability events happened within a region that since the LIA suffered a strong glaciers area contraction (-69.44%). This research testifies how the mountains are rapidly reacting to climate change and deglaciation, highlighting that alpine routes crossing the glaciers of our study region cannot be considered outside the potential runout zone of a rockfall.