Spaceborne monitoring of the recent contribution of Andean glaciers to water resources and sea level rise

Séminaire de Ines Dussaillant (LEGOS, Toulouse), jeudi 5 décembre, 11h, salle Lliboutry, Bâtiment de Glaciologie

Scarce and short-term measurements suggest that Andean glaciers are amongst the fastest-shrinking ice masses in the world. Comprehensively quantifying the magnitude of recent glacier loss in this region is crucial to better constrain future economical, ecological and social impacts. First, we evaluate in the Northern Patagonian Icefield the performance of a methodology to calculate glacier mass changes using time series of digital elevation models (DEMs) derived from Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) stereo images. After validation of the so called ‘ASTER monitoring Ice towards eXtinction’ (ASTERIX) method, we calculate the volume of ice lost by the integrity of Andean glaciers during the past 18 years and the corresponding contribution to sea level rise. We also evaluate the inter-decadal variability of mass loss in every Andes subregion and the decadal hydrological impacts on selected river basins. We find continuous mass loss in South Patagonia and the Tropics. Conversely, Dry Andes glaciers were stable during the 2000s, shifting to drastic thinning during the 2010s, amidst conditions of sustained drought. The evaluation of the imbalanced glacier contribution to river discharge during these two decades revealed that glaciers in the Dry Andes partially helped to mitigate the negative impacts of this sustained drought. The results obtained in this thesis contribute to the understanding of recent Andean glacier evolution at a local, regional and Andes-wide scale. We provide a high-quality, highly resolved and multi-decadal dataset that will be useful to constrain the diversity of present 21th century Andes-wide mass loss estimates, and contribute to the better calibration of glaciological and hydrological models intended to project future glacier changes and improve water resource management in the Andes.