Two Decades of Glacier Mass Balance in the Southern Andes

Glaciers are crucial components of the Earth's climate system and serve as indicators of climate change. Their substantial mass loss due to global warming significantly contributes to sea-level rise and impacts regional hydrology, downstream ecosystems and settlements. Despite considerable advancements in observational and modeling techniques, accurately quantifying glacier responses to climate change and predicting their future behavior remain complex challenges, particularly in regions characterized by rapidly changing glaciers and complex topography. In this study, we present a spatially resolved time series of annual glacier mass balance and elevation change for the Southern Andes from 2002 to 2025, derived from ASTER digital elevation models (DEMs). All available austral summer-season DEMs were compiled to minimize seasonal bias, and an automated processing workflow was developed to generate elevation change maps for the entire region as well as for individual glaciers. This approach enables consistent, large-scale monitoring without reliance on in-situ measurements, making it particularly valuable for remote and data-scarce regions. Elevation differences were converted to mass balance estimates using density assumptions, allowing both regional-scale assessments and detailed analysis of glacier complexes. Our results reveal pronounced spatial and temporal variability in glacier thinning, including periods of accelerated mass loss and localized heterogeneity linked to topographic and climatic factors. The developed methodology provides a scalable framework for long-term glacier monitoring and contributes to improved understanding of regional cryosphere dynamics and their implications for water resources and sea-level rise.