CLIMATIC SENSITIVITY AND RESPONSE OF THE ALPINE CRYOSPHERE IN REMOTE MOUNTAIN AREAS

High-elevation glaciers are among the most sensitive indicators of climate change, responding rapidly to atmospheric warming with consequences for slope stability, water resources, and the preservation of paleoclimatic archives. Yet, despite major advances in the understanding of glacier energy and mass balance processes, significant uncertainties persist due to the scarcity of long-term observations from summit areas and the difficulty of reproducing the multiple processes, including accumulation, redistribution, and melt, that control the glacier mass balance and the formation and preservation of climatic signals in snow and ice. This thesis addresses these knowledge gaps by focusing on the summit region of Mt. Ortles (3905 m a.s.l., Eastern Italian Alps) and the Alto dell’Ortles Glacier, where a unique combination of continuous in situ observations, ice core analyses, and mass balance modelling exists. The work is structured around three interconnected themes. First, a new multi-year observational dataset of air, englacial, and permafrost temperatures collected between 2010 and 2016, which provides rare insights into the thermal regime of the summit cryosphere. These data reveal seasonally isothermal firn layers, cold englacial temperatures at depth, and widespread permafrost conditions on debris-covered and rock wall slopes, offering robust constraints for model implementation and baseline conditions for future change detection. Second, a mass balance model is applied to the Mt. Ortles drilling site for the period 1996–2011, with the aim of reconstructing the firn stratigraphy and generating a pseudo-proxy of atmospheric conditions corresponding to snow layers that survived ablation. This pseudo-proxy is then compared with stable isotope and pollen records from the ice core, offering improved dating and environmental interpretation of firn layers impacted by melt and percolation processes, including those associated with extreme warm events such as the summer of 2003. The approach refines the chronology of the core beyond what is achievable through traditional annual layer counting of isotopic and pollen oscillations, and enhances the reliability of paleoclimatic reconstructions at mid-latitude high-altitude sites. Third, the thesis explores the control of air temperature on the snow susceptibility to wind erosion, through the application of the physically based SNOWPACK model, forced by detailed meteorological observations collected on Mt. Ortles between 2011 and 2015. The model reproduces observed snow water equivalent with high accuracy and allows for the identification of 1886 hourly erosion events, differentiated between dry and wet snow regimes. The results show that wind speed governs erosion magnitude at the event scale, while air temperature modulates snow erodibility through metamorphism, wetting, and refreezing. Sensitivity experiments applying temperature offsets from −3 to +3 °C demonstrate that warming systematically reduces wind erosion efficiency while strongly increasing melt, leading to a progressive shift from erosion-dominated to melt-dominated mass balance. Conversely, cooler scenarios enhance erosion losses due to the increased erodibility of cold, dry snow. Jointly, these findings provide new evidence of how atmospheric variability shapes the thermal state of the high-altitude cryosphere, governs snow accumulation and erosion processes, and influences the preservation and interpretation of glacial proxies in firn and ice. By integrating novel observations with process-based modelling, this thesis advances the understanding of the feedbacks linking atmosphere, snow and glacier dynamics at very high elevation, with implications for glacier change projections in alpine regions.