The Impact of Empirical Calving Laws on Thwaites Glacier Dynamics

Abstract:

Mass loss from the Amundsen Sea Embayment currently dominates Antarctica’s contribution to sea-level rise. Future estimates of mass loss and sea-level contribution from this sector of Antarctica depend on accurate estimates and predictions of basal properties, basal melt, and direct ice discharge through calving. Although significant progress has been made in inferring and predicting basal-melt rates through using satellite data as input to models, lack of understanding of calving processes remains a significant impediment to accurate predictions of ice discharge. Here we determine the impact of a range of calving laws, based on spatiotemporal observations within Pine Island Bay, on the dynamics of Thwaites Glacier (TG) as well as ice-ocean interactions beneath its ice tongue. Oceanic forcing of (once) buttressing ice shelves has been implicated as the driver of the ongoing changes in this region of the West Antarctic Ice Sheet and may have important ramifications for calving rate. Building on a suite of ice-ocean coupled model runs as well as similarly determined calving laws for a variety of representative ice shelves/tongues from Antarctica and Greenland, we include calving parameterizations for TG that range from simple freeboard limitations to regionally refined laws relating calving flux to spreading rate. Our results highlight the importance of including and constraining numerical representations of the calving process within prognostic ice-sheet models.