Glacier decline in the Central Andes (33°S): Context and magnitude from satellite and historical data

Abstract

Central Andes (33°S) represent a water-scarce region. During arid years, glacier runoff may constitute the main hydrological input at warm season and hence a steadfast deglacierization may represent a decrease in the regional water-budget. Ice-retreat enables landscape transitions from proglacial towards a paraglacial environment, allowing the formation of newly formed cryogenic deposits. Ice-surface changes in the Central Andes (33°S), including the high-mountain areas from Aconcagua, Mendoza and Maipo basins (Argentina and Chile), were studied using digitalized maps, aerial photographs, Landsat (1–8) and Sentinel-2A data for the period between 1956 and 2015. Band ratio and Normalized Difference Snow Index (NDSI) methods were tested using Landsat 8 and Sentinel-2A data for comparison. Geomorphological changes were assessed at Monos de Agua catchment (2750–4000 m a.s.l.) in the Aconcagua basin (Chile) as a regionally representative landscape transition case. Regional glacier shrinkage of 46 ± 5% between 1956 and 2016 was observed for the Central Andean sub-basins in both Argentina and Chile at 33°S. Overall, 107.1 ± 5 km2 of newly exposed surfaces are subject to permafrost conditions. Such insights raise concern in terms of current and future environmental assessments for newly formed cryospheric elements in water scarce regions.