The Effect of Submarine Melting on Calving From Marine Terminating Glaciers

Abstract

Submarine melting and iceberg calving are two important processes that control mass loss from the terminus of tidewater glaciers. There have been significant efforts to quantify the effect of submarine melting on glacier calving, but controversy remains with conflicting studies indicating submarine melting can increase, decrease, or has minimal effect on calving. Here we show using a two‐dimensional full Stokes finite element model that submarine melt can alter the state of stress near the terminus and the changes in stress exert a first‐order control on the calving regime of marine terminating glaciers. The model calculates both the largest principal and maximum shear stresses and then maps out where tensile and shear failure occur for a range of melt rates and vertical melt profiles. We find that submarine melt initially promotes full thickness calving events. However, as the melt rate further increases, an overhang begins to form and resulting compressive stresses suppress full thickness calving. These results are relatively insensitive to basal friction. Moreover, our results suggest that submarine melting can both increase and decrease calving rates with the magnitude and sign of the effect determined by the shape of the melt profile and the relative magnitude of average melt rate. Despite the fact that calving is suppressed in some circumstances, the addition of submarine melt almost always increases the total mass loss. Overall, we find that relatively small amounts of submarine melt can destabilize glaciers, but calving and frontal ablation are increasingly controlled by submarine melt as it continues to increase.