Local variability of small Alpine glaciers: Thoula Glacier geodetic mass balance reconstruction (1991-2020) and analysis of volumetric variations

Abstract

High Alpine environments are rapidly changing in response to climate change, and understanding the evolution of small glaciers is a crucial step in the investigation of future water availability for populations that inhabit these areas. With this study, we present a comprehensive analysis of a small glacier’s recent mass balance evolution (1991-2020), located on the Italian side of the Mont-Blanc Massif, where very little previous data were available. To do so, we combined historical data (topographic surveys and LiDAR DEMs of the area) with newly acquired satellite stereo imagery and aerophotogrammetric surveys to obtain multi-temporal digital elevation models (DEMs) of the Thoula Glacier (0.52 km²). The total ice volume estimation was assessed by accomplishing a GPR survey to investigate the ice thickness and the underlying bedrock. The Thoula Glacier shows a significantly lower loss of volume in comparison to other glaciers located in the Aosta Valley region as well as most of the reference glaciers of the Word Glacier Monitoring Service (WGMS) for Central Europe. Particular weather-climatic conditions of the Mont Blanc Massif area, generally characterized by a greater amount of precipitation, could explain the observed differences; however, the present study shows that understanding spatio-temporal local variability of small glaciers can significantly contribute to recognizing different regional and intra-regional patterns of response to climate change.