Abstract
Glaciers in the Alps are rapidly receding. Different publications suggest that in this epoch they are out of balance with the climate. In 2020 (Paul et al., 2020) it was possible to count a total of 4395 glaciers all over the Alps. Nonetheless the situation is critical. The Swiss Glacier Inventory 2010 (M. Fischer et al., 2014) reports a glacier area loss of 27.7% since 1973. Between 1969 and 1998 Austrian glaciers suffered an area decreased by about 17%; Knoll and Kerschner (2009) reported an area decrease for the South Tyrol glaciers of approximately 36% between 1983 and 2006.
Glacier recession is causing the occurrence of new phenomena and problems. These situations are often unpredictable and threaten many lives, such as the Marmolada collapse. Another interesting situation posed by the deglaciation is the paraglacial activity. The withdrawal of glacier ice exposes landscapes that are in an unstable state and consequently, due to a release of stress (debuttressing), subjected to modification and erosion (Ballantyne, 2002). This erosion is not only a threat for alpinists but also causing the release of debris over glaciers modifying their surface properties, consequently influencing their energy balance and melting rates.
The main objective of this research is to define how glaciers in the Venosta valley are reacting to climate change, providing data about their temporal evolution, a description of the main glaciological parameters between 1997 and 2020 and an assessment of possible hazards posed by the deglaciation. Two new inventories are now available, one describing the glaciers and one the landslides near the glaciers. The digitalization was conducted manually and following investigations were performed with remote sensing approaches; in particular Landsat satellites were used. With this research, in the area of interest, it was possible to reconstruct the 2020 glaciers extension which was then compared with previous data. Also the lost volume between 2006 and 2017 was computed and other formulas providing the total glacier average thickness and volume were applied. In the final part of this research, the collected data are reviewed together to evaluate possible correlations and trends. In addition, a focus over a specific unstable glacier (Vallelunga/Langtaufer Ferner) is provided. This specific case study helps demonstrate that due to new instabilities, it is required to review some alpine paths and alpinists are required to recognize new possible hazards.
This research proves how each glacier is reacting as a system; indeed, increased temperature generates melting, but also new geomorphological events that reinforces the melting acting over the surface properties and posing new threats.
In general, these assessments provide interesting results about the actual deglaciation phase testifying that important changes are detectable even during short periods.