Abstract/Summary

The accumulation of surface meltwater on ice shelves can lead to the formation of melt lakes. Melt lakes have been implicated in crevasse propagation and ice shelf collapse; the Larsen B ice shelf on the Antarctic Peninsula was observed to have a large amount of melt lakes present on its surface just before its collapse in 2002. Such collapse can affect ocean circulation and temperature, and cause a loss of habitat. Additionally, it can cause a loss of the buttressing effect that ice shelves can have on their tributary glaciers, thus allowing the glaciers to accelerate, contributing to sea level rise. We present results of a 1-D mathematical model of surface melt on an idealised ice shelf. The model incorporates a calculation of the surface energy balance of an ice shelf, heat transfer through the upper ice shelf, the production and percolation of meltwater into the firn, the formation of ice lenses in the firn and the formation, development and refreezing of surface melt lakes on the ice shelf. The melt lake model is applied to the Larsen C Ice Shelf, located on the Antarctic Peninsula, where melt lakes have been observed. The Antarctic Peninsula has warmed several times the global average over the last century and Larsen C has been suggested as a candidate for becoming fully saturated with meltwater by the end of the current century. When forced with automatic weather station data from Larsen C, our model produces surface melting, meltwater accumulation, melt lake development and refreezing consistent with current observations. We examine the sensitivity of lake formation to uncertain parameters, and provide evidence of the importance of processes such as the lateral transport of meltwater (and thus ice shelf topography) to the formation of surface lakes, a process without which lakes were not found to form. Furthermore, we investigate the impact on melt lakes and the surface energy balance of possible future atmospheric conditions.