Response of Onshore Oceanic Heat Supply to Yearly Changes in the Amundsen Sea Icescape (Antarctica)

Abstract

AbstractThe heat transfer between the warm oceanic water and the floating portion of the Antarctic ice sheet (the ice shelves) occurs in a dynamic environment with year‐to‐year changes in the distribution of icebergs and fast‐ice (the “icescape”). Dramatic events such as the collapse of glacier tongues are apparent in satellite images but oceanographic observations are insufficient to capture the synoptic impact of such events on the supply of oceanic heat to ice shelves. This study uses a 3D numerical model and semi‐idealized experiments to examine whether the current high melting rates of ice shelves in the Amundsen Sea could be mitigated by certain icescape configurations. Specifically, the experiments quantify the impacts on oceanic heat supply of presence/absence of the Thwaites Glacier Tongue, Bear Ridge Iceberg Chain, tabular iceberg B22, and fast‐ice cover seaward of Pine Island Ice Shelf (PIS). The experiments reveal that future changes in the coastal icescape are unlikely to reverse the high ice shelf melting rates of the Amundsen Sea, and that icescape changes between 2011 and 2022 actually enhanced them slightly. Ice shelves such as Crosson and Thwaites are found to have multiple viable sources of oceanic heat whose relative importance may shift following icescape reconfigurations but the overall heat supply remains high. Similarly, the formation of a fast‐ice cover seaward of PIS slows down the cavity circulation (by 7%) but does not reduce its heat supply.