Untangling multi-annual to decadal ice mass loss of glaciers in the Patagonian Andes

The Patagonian Andes host the largest glacierized area in the Southern Hemisphere outside Antarctica and play a key role in regional freshwater resources and global sea-level rise. Meltwater discharge from Patagonian glaciers contributes to sea-level rise, while changes in freshwater runoff threaten downstream ecosystems and water availability. In particular, the Northern Patagonian Icefield (NPI), Southern Patagonian Icefield (SPI), and Cordillera Darwin Icefield (CDI) are vast temperate ice bodies and rank among the Earth`s mountain regions with the highest glacier mass-loss rates.

Here, we present new observations of glacier mass change across the Patagonian Andes for the period 2000–2025. We combine multi-mission remote sensing data, including synthetic aperture radar (SAR) digital elevation models (DEMs) from the TanDEM-X mission and satellite altimetry from CryoSat-2 and ICESat-2, to derive glacier-specific and regional geodetic mass changes. In addition, we account for ice mass loss committed by frontal ablation by estimating subaqueous volume change of lake- and marine-terminating glaciers from observed terminus retreat and ice thickness reconstructions.

Comparison with climate observations reveal a region-wide warming trend since the beginning of the 21st century. However, regional glacier mass change exhibits pronounced spatial and temporal heterogeneity. NPI glaciers show a marked acceleration in mass loss after 2013, while at SPI mass loss rates remained comparatively stable until 2019, after which annual mass loss increased to levels similar to the NPI. Similarly, the CDI exhibits a distinct increase in mass loss in recent years, after a short intermediate period of mass loss deceleration. Glacier-specific analyses of surface elevation change and ice flow velocity at major outlet glaciers reveal enhanced surface lowering and increased flow speeds near glacier termini over the past decade, due to intensified dynamic thinning. The observed regional and temporal variability in glacier response is likely linked to previously reported variations in precipitation and snowfall amounts. Overall, annual specific mass loss of the NPI and SPI since 2019 (~ -1.5 m w.e./a) has increased by more than 50% compared to the early 2000s (~ -1.0 m w.e./a).