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

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.

Modeling the instantaneous response of glaciers after the collapse of the Larsen B Ice Shelf

“…Despite the previous disintegration of smaller ice shelves around the Peninsula in response to a changing climate [Rott et al, 1996;Scambos et al, 2000;Cook and Vaughan, 2010], the rate and extent of the 2002 collapse was exceptional and the most dramatic observed so far. Good satellite coverage before, during, and after the disintegration, complemented by ground-based measurements, made this one of the best documented large-scale events in recent history of the cryosphere.…”

Summertime water masses off the northern Larsen C Ice Shelf, Antarctica

“…At the present rate of thinning, they predict that it will take LCIS around 100 years to reach the thickness of Larsen B Ice Shelf at the time of that ice shelf's collapse. Other authors believe that the fundamental cause of the retreat of the northern Larsen ice shelves is atmospheric warming [Vaughan and Doake, 1996;Scambos et al, 2000;Morris and Vaughan, 2003].…”

Changing distributions of sea ice melt and meteoric water west of the Antarctic Peninsula

“…The annual duration of the melt season at the WAP has increased in recent decades, which is suggested to have contributed to ice shelf collapse (Scambos et al, 2000;van den Broeke, 2005) and the acceleration and thinning of glaciers (Pritchard and Vaughan, 2007) and although most of the meltwater will percolate down and refreeze within the firn layer, there is still the potential for an increase in runoff to the ocean (Barrand et al, 2013b;Vaughan, 2006). Overall, 80% of the glaciers at the WAP are known to have retreated during the second half of the twentieth century, with a recent tendency toward accelerated retreat (Cook et al, 2005).…”