Inventory of paraglacial slope instabilities following glacier retreat in 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 historical precedents from the early 21st century. Mountain glaciers are important resources for society because they provide different ecosystem services. Climate change is threatening the stability of these benefits, and, as a result of permafrost thaw and post-glacial debuttressing, it is causing the emergence of climate-related hazards at high altitude. To understand how mountain slopes react to deglaciation, we compiled the first inventory of paraglacial slope instability phenomena that have occurred on glaciers in the Venosta Valley (Italy) since the Little Ice Age (LIA). We mapped their geographical distribution, evaluated their relationship with deglaciation, and examined their runout to assess the potential implications of such events for alpine routes. To better quantify deglaciation, we also digitized the outlines of the glaciers based on imagery from 2020, updating the archives and providing valuable data for comparison with previous studies. Between 2000 and 2020, a total of 500 slope instability events occurred within a region that, since the LIA, has experienced strong glacier area contraction (-69.44%). This research demonstrates how the mountains are rapidly responding to climate change and deglaciation, highlighting that alpine routes crossing the glaciers in our study region cannot be considered outside the potential runout zone of a rockfall.