The link between climate warming and break-up of ice shelves in the Antarctic Peninsula

TLDR

Climate warming in the Antarctic Peninsula has lengthened melt seasons and increased ice‑shelf ponding. The study tests whether meltwater‑induced crevasse propagation drives ice‑shelf retreat in the region. A thermodynamic finite‑element model of ice flow and strain, extended to simulate meltwater‑filled crevasse propagation, evaluates the weakening mechanism. Longer melt seasons and melt‑pond presence predict break‑ups, and the model confirms meltwater‑driven crevasse propagation as the key weakening mechanism.

Abstract

Abstract A review of in situ and remote-sensing data covering the ice shelves of the Antarctic Peninsula provides a series of characteristics closely associated with rapid shelf retreat: deeply embayed ice fronts; calving of myriad small elongate bergs in punctuated events; increasing flow speed; and the presence of melt ponds on the ice-shelf surface in the vicinity of the break-ups. As climate has warmed in the Antarctic Peninsula region, melt-season duration and the extent of ponding have increased. Most break-up events have occurred during longer melt seasons, suggesting that meltwater itself, not just warming, is responsible. Regions that show melting without pond formation are relatively unchanged. Melt ponds thus appear to be a robust harbinger of ice-shelf retreat. We use these observations to guide a model of ice-shelf flow and the effects of meltwater. Crevasses present in a region of surface ponding will likely fill to the brim with water. We hypothesize (building on Weertman (1973), Hughes (1983) and Van der Veen (1998)) that crevasse propagation by meltwater is the main mechanism by which ice shelves weaken and retreat. A thermodynamic finite-element model is used to evaluate ice flow and the strain field, and simple extensions of this model are used to investigate crack propagation by meltwater. The model results support the hypothesis.