Updating our understanding of oceanic controls on glacier terminus retreat along the west Antarctic Peninsula

David Sutherland1, Kiya L Riverman2, Michael S Dinniman3, Carlos F Moffat4, Borja Aguiar-González4, Ryan Obermeyer2 and John Michael Klinck II5, (1)University of Oregon, Eugene, OR, United States, (2)University of Oregon, Eugene, United States, (3)Old Dominion University, Center for Coastal Physical Oceanography, Norfolk, VA, United States, (4)University of Delaware, Newark, DE, United States, (5)Old Dominion University, Center for Coastal Physical Oceanography, Norfolk, United States
In the past decade, increased delivery of Circumpolar Deep Water (CDW) to the Antarctic Peninsula continental shelf has driven considerable retreat of ocean-terminating glaciers. West Peninsula glaciers now contribute strongly to observed sea level rise. In order to forecast the response of Peninsula glaciers to continued change in delivery and temperature of CDW, we relate glacier grounding zone depths along the western Peninsula to 1) observed ocean conditions from a newly developed hydrographic dataset, and 2) inferred melt rates from plume modeling and a set of 3-D, high-resolution MITgcm simulations. Glacier terminus geometries are estimated from previously published mass-conservation products, IceBridge radar, and optical imagery. We find a strong correlation between glacier retreat and grounding zone ocean temperature. Glaciers that ground deeply in warm waters have strong retreat rates, while glaciers that have shallower grounding zones and are not in contact with deep, warm water masses have experienced little retreat in the past 50 years. This is further supported by comparing melt rates and circulation near these glacier fronts from both 1-D buoyant plume modeling and fully 3-D MITgcm ice-ocean coupled simulations. We find that circulation near these glaciers is dominated by variability on the continental shelf and not by glacial melt itself (i.e., buoyancy-driven flow). These results have implications for the response of glaciers along the Peninsula to future changes in the position and/or strength of the westerlies and delivery of CDW to the continental shelf.