Sensitivity of Barnes Ice Cap, Baffin Island, Canada, to climate state and internal dynamics

Barnes Ice Cap is a remnant of the Laurentide Ice Sheet, which covered much of northern North America during the Last Glacial Maximum. Barnes reached a quasi-equilibrium state similar to 2000years ago and has remained similar in size since then, with a small increase during the Little Ice Age. In this study, we combine historical observations (1960-1980) with more recent satellite and airborne data (1995-2010) to drive a mass balance model coupled to a transient thermomechanical model with an adaptive mesh geometry. The model is used to characterize the current state of the ice cap and to investigate its stability as a function of climate and its own internal dynamics. On millennial time scales we show that ice flow is influenced by adjustment of an unsteady shape, by gently sloping bedrock, and by contrasting viscosities between the Pleistocene and Holocene ice. On shorter time scales, Barnes is affected by surge activity. Sensitivity tests reveal that Barnes experienced climate conditions which enabled its stability 2000 to 3000years ago but will disappear under current climate conditions in the next millennium.