Recent retreat and climatic drivers of the Universidad glacier, central Chilean Andes

Mountain glaciers in central Chile are highly sensitive to climatic variability, yet glacier-specific, long-term assessments remain limited in transitional climatic zones. This study quantifies recent changes in the Universidad Glacier (central Chilean Andes) using a multi-decadal remote sensing approach integrated with atmospheric and hydrometeorological data. Glacier surface area was mapped from Landsat (1975–2025) and Sentinel-2 (2016–2025) imagery, while climate forcing was characterized using radiosonde temperature profiles, gridded precipitation products, and satellite-derived snow-cover data. Results indicate a sustained glacier retreat, with a net surface-area loss of approximately 5 km2 between 1990 and 2025 and accelerated shrinkage since the early 2000s. Mid-tropospheric warming and a rise in the annual mean zero-degree isotherm, frequently exceeding 4,000 m a.s.l. in recent years, coincide with declining winter precipitation and reduced snow cover. These changes have driven an upward shift of the equilibrium-line altitude of more than 400 m and a persistently negative surface mass balance. The findings demonstrate the value of combining long-term satellite observations with atmospheric data to diagnose climate-driven glacier change in data-sparse mountain regions.