Geophys. Res. Lett 35. L07502 (2008)

Credit: UNIVERSITY CORPORATION FOR ATMOSPHERIC RESEARCH

Computer models of climate change have overstated Antarctic warming, say scientists. The large volumes of water locked up in the Antarctic's ice sheets, which could raise sea level if melted, have created intense interest in how much the region is likely to warm.

Traditionally, this has been estimated mainly from models, as observations on the ground are sparse. But Andrew Monaghan at Ohio State University and colleagues have now compiled temperature and snowfall data across Antarctica and compared them to model simulations. Monaghan's team found that whereas the models estimated about a 0.75 °C temperature rise over the last century, temperatures actually rose by only 0.2 °C over the continent. One exception is the Antarctic peninsula, which has warmed by several degrees. The models did a good job of representing changes in snowfall, which increased in the later part of the twentieth century and decreased in the past decade.

The discrepancy in temperature change may result from the models overestimating the amount of water vapour in the Antarctic atmosphere. Interestingly, when temperatures are colder over Antarctica, there is less snowfall to replenish the ice sheet, which could potentially increase sea level rise, although other factors also affect the overall amount of ice on the continent.