All climate models participating in the IPCC AR4 assessment as made available by PCMDI (Program for Climate Models Diagnostics and Inter-comparison) as the CMIP3 (Coupled Model Intercomparison Project 3) archive predict a significant surface warming of Antarctica by the end of the 21st century under a moderate (SRESA1B) greenhouse gas scenario. All models but one predict a concurrent precipitation increase but with a large scatter of results. The models with finer horizontal resolution tend to predict a larger precipitation increase. Because modeled Antarctic surface mass balance is known to be sensitive to horizontal resolution, extrapolating predictions from the different models with respect to model resolution may provide simple yet better multi-model estimates of Antarctic precipitation change than mere averaging or even more complex approaches. Using such extrapolation, a conservative estimate of the predicted precipitation increase at the end of the 21st century is +30 kg m-2 yr-1 on the grounded ice-sheet, corresponding to a moderation by more than at least 1 mm yr-1 of sea-level rise. About three quarter of this moderation originates from the marginal regions of the Antarctic ice sheet with surface elevation below 2250 m. This is where field programs are most urgently needed to better understand and monitor accumulation at the surface of Antarctica, and to improve and verify prediction models.

Last Updated: 2008-09-23