The Decline of a Caldera‐Filling Glacier at Volcán Sollipulli, Chile

Le résumé fourni par la source

Abstract Southern Andean glaciers have undergone fast retreat in recent decades. This results in reduced freshwater storage, contribution to sea‐level rise, and locally to the formation of glacial lakes, that may pose the risk of glacial lake outburst floods (GLOFs). The glacier of Volcán Sollipulli in the Chilean Andes (39°S) is currently entirely confined within a caldera of about 4 km in diameter, resulting in an atypical glacier geometry. The glacier surface is very flat at about 2,075 m elevation, and its maximum ice thickness of around 750 m makes it the deepest measured ice body in the Andes north of the Patagonian Ice Fields. Using remote sensing data and field measurements, we investigate the surface elevation change of Sollipulli Glacier during the 21st century. Our results reveal that while surface lowering occurred during 2000–2015, the rate more than doubled thereafter, leading to about 70 m surface lowering since the year 2000. This lowering coincides with observations of glacier‐wide summer snow absence, indicating that the equilibrium line altitude has risen above the maximum glacier surface altitude. Consequently, continued glacier surface lowering amplifies melt through a melt‐elevation feedback, further accelerating mass loss. Ongoing ice loss has led to the development of at least one proglacial lake dammed by terminal moraines. We discuss the future evolution of Sollipulli Glacier and hypothesize that further ice loss will ultimately transform the glacier into a caldera lake, with significant implications for regional hydrology and GLOF hazards.

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