Past, present, and future glacier evolution in the Tropical Andes

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Glaciers and ice caps outside the polar ice sheets are strongly affected by climate change, and various observables are defined as essential climate variables. Glacier shrinkage has local to regional-scale impacts on hydrology, ecosystems, and society. In the Tropical Andes, the glaciers pose an important water resource and significantly contribute to the local and regional water supply, especially during the dry season and drought periods. Moreover, glacier retreat increases the risk of glacier lake outburst floods putting downstream communities at risk. To improve future water management and risk assessment as well as to evaluate the impact of climate variations, region-wide and detailed information on the past, present, and future glacier evolution in the Tropical Andes is required. Current glacier mass change estimates have spatiotemporal limitations and often considerable uncertainties, while regional projections, carried out within global analyses, show partly ambiguous trends. This project aims to overcome these deficiencies by comprehensively analyzing the Tropical Andes' past, present, and future glacier evolution. An improved regional assessment of current and future glacier changes will be conducted based on an innovative combination of multi-mission remote sensing data, in-situ measurements, and glacier and hydrological modeling. In combination with data on past glacier changes, which are obtained by exploiting unique remote sensing archives, the evaluation of the long-term trend and its relation with climate change will be facilitated. By assimilating the new remote sensing products and in-situ observations into an ice-dynamic model inversion, highly improved ice volume distribution information will be generated. Projections of glacier evolution for the Tropical Andes until 2100 using mass balance modeling, optimized for the tropics, and fully 3-dimensional glacier modeling will be conducted to overcome the shortcomings of existing global estimates. Those activities will facilitate the subsequent study of the glacier lakes evolution and the glacier meltwater contribution to catchment runoff. The outcomes of this project will include novel and improved regional information regarding the glacier evolution in the Tropical Andes and methodological advances. These comprise (1) region-wide enhanced quantification of the ongoing glacier changes, the evaluation of its long-term trend and correlation with climatic variations, (2) development of innovative remote sensing and modeling techniques, (3) improved ice thickness information and projections of glacier and runoff evolution using fully coupled, 3D-distributed and optimized modeling.