Bed topographic control on outlet glacier retreat and stability in Greenland.

Abstract:

Outlet glaciers in Greenland are influenced by a myriad of environmental parameters on a range of time scales, which makes their dynamic response to climate perturbations complex. Recent work has highlighted the sensitivity of outlet glacier termini to changes in ocean and atmospheric conditions. However, while most glaciers are undergoing rapid terminus retreat in response to climate warming, there is significant heterogeneity in the amount of retreat occurring across the ice sheet. Some glaciers experience large and rapid retreat of the terminus, while neighboring glaciers appear to be buffered against retreat. Here we investigate the importance of bed topography at the glacier terminus in setting the total amount of retreat across a number of outlet glaciers in Greenland. We use topographic data and terminus positions to test the hypothesis that total glacier retreat is correlated to the length of overdeepening behind the glacier terminus. We also investigate the relatively small number of stable glaciers in Greenland in order to specifically examine the geometric properties of their terminal moraines. By comparing moraine geometry for stable versus retreating glaciers we may be more able to understand the observed heterogeneity in outlet glacier retreat in Greenland.