Abstract

Studies of mass balance show that the Greenland Ice Sheet is losing mass at a growing rate, and that that the contribution to sea level rise could reach 1 mm per year within a decade. Part of this loss is caused by increased surface melting, which is widespread, but limited to the ice sheet’s ablation zone. The other part is caused by faster rates of ice flow, a localised mechanism linked to glaciers terminating in fjords, but with potential far-reaching consequences for the flow of the entire ice sheet. The key question, which has yet to be fully resolved, is whether these two mechanisms are coupled in a positive feedback. This talk will present outcomes from a 3D higher-order ice sheet model, with soft bed and hydrology included in novel new parameterizations. The results demonstrate that a resilient characteristic of ice flow, corresponding to recent observations, may be linked to the storage of surface melt-water in subglacial sediment. This stable mechanism may, however, vanish as climate warms and be limited to regions where the ice sheet terminates on land.