The Effect of Submarine Melting on Iceberg Calving

It is widely known that submarine melting can largely affect calving behavior of tidewater glaciers by removing supportive mass from the calving front. There have been both observational and modeling efforts that indicate a positive correlation between submarine melting and iceberg calving, with some claiming that the total mass loss is unchanged. However, it still remains unclear how and which direction submarine melting influences calving rate. We want to investigate this question by building on our 2D full-Stokes glacier calving model, which not only takes into consideration both surface and basal crevasses but tensile and shear failure regimes as well. A variety of submarine melt rates and profiles are considered in order to investigate the resulting shape of the calving front and thus its influence on local stress field and glacier calving behavior. We find that once an overhang starts to form, areas of large tensile and shear stress tend to grow around the part where the overhang connects to the rest of the glacier, making the ice more likely to calve off from the glacier. Given the same ice thickness and water depth, glaciers with increased submarine melting are more vulnerable to calving; given the same ice thickness and submarine melt rate, glaciers terminating in deeper water are more vulnerable to calving. Nevertheless, the sizes of the icebergs that break off are smaller compared to those without submarine melting, which might serve to explain the unaffected total mass loss in spite of an increased frequency of calving events. By examining the change of stress field near the glacier front, our model offers a physical insight into the way submarine melting modifies the calving dynamics.