2025 CSDMS meeting-127
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Surface mass balance–driven ice flow emulator underpredicts terminus retreat at lake-terminating glaciers
Jocelyn Reahl,
(she/her),University of Colorado Boulder Boulder Colorado, United States. jocelyn.reahl@colorado.edu
Irina Overeem, University of Colorado Boulder Boulder Colorado, United States. irina.overeem@colorado.edu
William Armstrong, Appalachian State University Boone North Carolina, United States. armstrongwh@appstate.edu
Guillaume Jouvet, University of Lausanne Lausanne , Switzerland. guillaume.jouvet@unil.ch
Glaciers around the world are retreating in response to climate change, leaving behind tens of thousands of glacier-contact lakes in their wake. Some lake-terminating glaciers have been observed to flow, lose ice mass, and retreat at faster rates than land-terminating glaciers. However, these observations appear to contradict theory, which suggests that the cold, freshwater, and shallow conditions in these lakes should inhibit ice calving and melting—collectively “frontal ablation”—at the glacier terminus. To resolve this discrepancy between theory and observations, we must disentangle the relative influence of surface mass balance and frontal ablation on observed glacier retreat. In this study, we modeled three lake-terminating glaciers on the Juneau Icefield, Alaska (Gilkey, Meade, and Field) from 2005–2019 using a physics-informed ice flow model emulator—the Informed Glacier Model (IGM). We drove IGM with surface mass balance outputs from a COupled Snowpack and Ice surface energy and mass-balance (COSIPY) climate reanalysis model of the Juneau Icefield. These glacier simulations were then compared with LANDSAT-observed glacier terminus positions from 2005-2019 to assess modeled predictions of lake-terminating glacial retreat.
Preliminary results indicate that when the ice flow model is only forced by surface mass balance—as current theory suggests for lake-terminating glaciers—IGM underpredicts observed terminus retreat at all three glaciers. These results suggest that lake-terminating glaciers on the Juneau Icefield are experiencing an additional component of ice mass loss that significantly contributes to terminus retreat. Upcoming modeling work will aim to verify the quality of these preliminary results by performing similar model runs on land-terminating glaciers in the Juneau Icefield (e.g. Lemon Creek Glacier) as a control case. We will also perform field campaigns over 2025-2027 to the Gilkey, Meade, and Field glacier termini to quantify their in-situ ice mass loss rates.
