Articles | Volume 8, issue 6
Research article
16 Dec 2014
Research article |  | 16 Dec 2014

Are seasonal calving dynamics forced by buttressing from ice mélange or undercutting by melting? Outcomes from full-Stokes simulations of Store Glacier, West Greenland

J. Todd and P. Christoffersen

Abstract. We use a full-Stokes 2-D model (Elmer/Ice) to investigate the flow and calving dynamics of Store Glacier, a fast-flowing outlet glacier in West Greenland. Based on a new, subgrid-scale implementation of the crevasse depth calving criterion, we perform two sets of simulations: one to identify the primary forcing mechanisms and another to constrain future stability. We find that the mixture of icebergs and sea ice, known as ice mélange or sikussak, is principally responsible for the observed seasonal advance of the ice front. On the other hand, the effect of submarine melting on the calving rate of Store Glacier appears to be limited. Sensitivity analysis demonstrates that the glacier's calving dynamics are sensitive to seasonal perturbation, but are stable on interannual timescales due to the strong topographic control on the flow regime. Our results shed light on the dynamics of calving glaciers and may help explain why neighbouring glaciers do not necessarily respond synchronously to changes in atmospheric and oceanic forcing.

Short summary
Many iceberg-calving glaciers in Greenland have recently been observed to accelerate and retreat, prompting fears about their future stability in the face of climate change. We present results from a flow modelling study of Store Glacier, West Greenland, which suggest that glacier geometry may play an important role in determining calving glacier stability. Store Glacier flows into a narrow, shallow fjord and our model suggests this may make it insensitive to future ocean warming.