The influence of recent Antarctic ice sheet retreat on simulated sea ice area trends

Observations indicate that dynamic mass loss from the Antarctic ice sheet has been accelerating over recent decades, leading to a freshening of the Southern Ocean. Here we quantify the effect of several rates and spatial distributions of freshwater forcing on simulated sea ice area trends. In contrast to a previous study, our simulations show that the freshwater effect on sea ice trends over the historical period is small and fails to reproduce the observed regional pattern of trends, when using observationally consistent rates of freshwater forcing. The Coupled Model Intercomparison Project Phase 5 (CMIP5) models do not represent this dynamic ice sheet mass loss, and it has been suggested that this deficiency may significantly influence the simulated sea ice trends. We show that when accounting for internal variability, the average CMIP5 sea ice area trend is statistically consistent with the observed trend, and accounting for ice sheet derived freshwater forcing has little influence.