Modeling of Store Gletscher's calving dynamics, West Greenland, in response to ocean thermal forcing

Glacier‐front dynamics is an important control on Greenland's ice mass balance. Warmer ocean waters trigger ice‐front retreats of marine‐terminating glaciers, and the corresponding loss in resistive stress leads to glacier acceleration and thinning. Here we present an approach to quantify the sensitivity and vulnerability of marine‐terminating glaciers to ocean‐induced melt. We develop a plan view model of Store Gletscher that includes a level set‐based moving boundary capability, a parameterized ocean‐induced melt, and a calving law with complete and precise land and fjord topographies to model the response of the glacier to increased melt. We find that the glacier is stabilized by a sill at its terminus. The glacier is dislodged from the sill when ocean‐induced melt quadruples, at which point the glacier retreats irreversibly for 27 km into a reverse bed. The model suggests that ice‐ocean interactions are the triggering mechanism of glacier retreat, but the bed controls its magnitude. Store is remarkably stable due to the presence of a sill in the vicinity of its frontA quadrupling of ocean‐induced melt is required to dislodge the glacier from its stabilizing sillA temporary increase in melting at the front can trigger a dramatic retreat of the glacier