Studying climate change, present glacier landscapes and future lake formation in Swiss Southwestern Alps
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Accelerated ice loss has been the most pronounced sign of climate change in high-mountain regions around the world. One of the outcomes of such changes is the formation of new lakes upon unstable slopes, a process that frequently observed in the Swiss Alps and poses threats to downstream settlements in the form of Glacier Lake Outburst Floods (GLOFs). Here, we first investigated the interactions between local meteorological variables, distant large-scale atmospheric and oceanic patterns, and glacier mass balance components to understand the response of the southwestern Swiss glaciers to observed climatic trends. The results show that all selected glaciers have lost their equilibrium condition in the recent decades with the persistent negative annual mass balance trends, and decreasing accumulation area ratios (AARs), accompanied by increasing air temperatures by +0.45°C decade-1, under the influence of Atlantic Multidecadal Oscillation (AMO), Greenland Blocking Index (GBI) and East Atlantic (EA) teleconnections. Forecasting results out to 2030 suggest that the smaller glaciers will continue to melt faster because of their inability to adjust to warming climate conditions as well as increases in long-wave heat input from the bare slopes. We also observed the current glacier landscapes and mapped the glacier facies and debris-covered surfaces using Landsat 8 OLI and TIRS data, which can eventually advance the accurate selection of future lake sites and associated hazards. With improvements in the spatial resolution of satellite images, and geomorphometry-related approaches, we could also estimate glacier ice thickness and simulate the glacier bed topography after glaciers decline. By linking three morphological criteria to the modelled overdeepenings over glacier bed topography, the possibility of these sites for future lake formation were determined. This study is a contribution to advance lake hazard management under the influence of climate change in high-mountain regions.