Increasing rate of 21st century volume loss of the Patagonian Icefields measured from proglacial river discharge

Abstract

The Northern and Southern Patagonian Icefields are rapidly losing volume, with current volume loss rates greater than 20 km3 a-1. However, details of the spatial and temporal distribution of their volume loss remain uncertain. We evaluate the rate of 21st-century glacier volume loss using the hydrological balance of four glacierised Patagonian river basins. We isolate the streamflow contribution from changes in ice volume and evaluate whether the rate of volume loss has decreased, increased, or remained constant. Out of 11 glacierised sub-basins, seven exhibit significant increases in the rate of ice volume loss, with a 2006-2019 time integrated anomaly in the rate of glacier volume loss of 135 ± 50 km3. This anomaly in the rate of glacier-volume-loss is spatially heterogeneous, varying from a 7.06 ± 1.69 m a-1 increase in ice loss to a 3.18 ± 1.48 m a-1 decrease in ice loss. Greatest increases in the rate of ice loss are found in the early spring and late summer, suggesting a prolonging of the melt season. Our results highlight increasing, and in some cases accelerating, rates of volume loss of Patagonia's lake-terminating glaciers, with a 2006-2019 anomaly in the rate of glacier volume loss contributing an additional 0.027 ± 0.01 mm a-1 of global mean sea-level rise.