Warming preserves Antarctic sea ice

Counter-intuitively, climate warming has led to Antarctic sea ice expansion, suggests a study published online in Nature Geoscience this week. The analysis suggests that cool freshwater derived from melt beneath the Antarctic ice shelves has insulated offshore sea ice from the warming ocean beneath - a negative feedback effect that is expected to continue into the future.

Richard Bintanja and colleagues present oceanographic observations showing that water originating from accelerated melting at the base of the Antarctic ice shelves has accumulated in the surface ocean around Antarctica. Using a climate model, they showed that sea ice expands during southern hemisphere autumn and winter in response to the development of this fresh, cool surface layer. They suggest that, as well as preserving southern sea ice, cool sea surface temperatures around Antarctica could also reduce snowfall on the continent.