Abstract ID: 28.7299 | Accepted as Talk | Talk/Oral | 2025-02-28 14:30 - 14:45 | Ágnes‐Heller‐Haus/Small Lecture Room

The Cordillera Darwin Icefield (CDI) in Tierra del Fuego is the third-largest temperate icefield in the southern hemisphere, storing at least twice the ice volume of the European Alps. More than half of the CDI glaciers are in direct contact with proglacial lakes or fjords, making them susceptible to changes both in the climatic surface mass and in frontal ice-loss dynamics. Remote sensing studies have observed important mass losses in the region over the last decades. The role of the atmosphere for the recent ice loss remains, however, unclear. The reason is the scarcity of in-situ observations on climatic conditions and glacier mass balance. Such measurements are challenging as the region shows harsh weather conditions and is difficult to access. The key objective of the presented study is to reliably disentangle the climatic imprint on glacier mass loss in the Cordillera Darwin for the last two decades. This climatic attribution is unprecedented and a unique opportunity to study the effects of climate variability and change in the higher mid latitudes of the southern hemisphere. By mass budgeting with remotely sensed mass balance observations, we furthermore derive a first estimate of frontal ablation and thus ice-dynamic controls on glacier changes in the CDI. To address these research objectives, we present a high-resolution simulation of climatic energy and mass balance for the entire CDI over the last two decades (2000-2023) conducted with the “COupled Snowpack and Ice surface energy and mass balance model in PYthon” (COSIPY). Climatic conditions are characterized by strong zonal gradients across the mountain range, that are reflected in the energy and mass fluxes. We show that the CDI has been climatically balanced in the recent two decades, but is entering a state of accelerated mass loss due to increasing surface melt related to an intense warming rate. We find that while ice dynamics are important for individual glaciers, atmospheric conditions exert the main control on the overall CDI glacier evolution in the past two decades.