Insights into supraglacial lake evolution on the Larsen-B ice shelf

Abstract:

The Larsen-B ice shelf was the second largest component of the Larsen ice shelf system in the Antarctic Peninsula. It collapsed in 2002, losing an area more than double the size of London (~3200 km²) to the sea. The collapse of Larsen-B has been attributed to a range of factors, although the dominant control over the fidelity of the ice shelf is thought to be climatological (melting on the ice shelf was three times higher in 2002 than the 1998-2001 average). Supraglacial lakes in particular have been implicated in the collapse; by repeatedly filling and draining, they likely weaken an ice shelf and precondition it for disintegration. However, abundant supraglacial lake coverage has been observed on Larsen-B for many years prior to its break-up and, in fact, surface conditions have been conducive to lake formation for several decades. Here, we use satellite observations and a hydrological model forced with estimates of melting and runoff from a regional climate model in order to investigate the response of supraglacial lakes to extreme melting in 2002 specifically, in contrast with typical supraglacial lake evolution in previous years. We also use state-of-the-art observations of ice shelf topography acquired by CryoSat-2 to examine the potential role of supraglacial lakes on the fate of the Larsen remnant, currently thought to be at risk of collapse by 2020.