Effects of basal-melting distribution on the retreat of ice-shelf grounding lines

The stability of marine ice streams depends on the distribution as well as the magnitude of melting beneath the adjacent ice shelf, as shown by new model results. Recent observations of rapid retreat of ice-shelf grounding lines in the Amundsen Sea sector of West Antarctica have highlighted the need for understanding how basal melting of ice shelves by warm ocean waters affects ice dynamics and potentially contributes indirectly to sea-level rise. We apply two ice stream-ice shelf flow line models to investigate the effects of varying the spatial distribution of basal melting on grounding-line dynamics. For experiments with identical average melting, we find that retreat increases significantly as melting is concentrated near the grounding line, indicating that knowledge of the basal-melting distribution is likely necessary for accurate prediction of grounding-line migration.