Sea ice surrounding Antarctica has expanded with record extent due to increased basal melting of Antarctic ice shelves, says a scientific study published online on Sunday.

Changes in sea ice significantly modulate climate change because of its high reflective and strong insulating nature.

In contrast to Arctic sea ice, sea ice surrounding Antarctica has expanded with record extent in 2010, says the article in the journal Nature Geoscience. This ice expansion has previously been attributed to dynamical atmospheric changes that induce atmospheric cooling. But a team from the Royal Netherlands Meteorological Institute (KNMI) in De Bilt claimed that their study shows that accelerated basal melting of Antarctic ice shelves is likely to have contributed significantly to sea-ice expansion.

The peer-reviewed paper presents observations indicating that melt water from Antarctica's ice shelves accumulates in a cool and fresh surface layer that shields the surface ocean from the warmer deeper waters that are melting the ice shelves.

The research team simulated these processes in a coupled climate model, and found that cool and fresh surface water from ice-shelf melt leads to expanding sea ice in austral autumn and winter. This powerful negative feedback counteracts Southern Hemispheric atmospheric warming.

Although changes in atmospheric dynamics most likely govern regional sea-ice trends, the scientists say that their analyses indicate that the overall sea-ice trend is dominated by increased ice-shelf melt. Cool sea surface temperatures around Antarctica could offset projected snowfall increases in Antarctica, with implications for estimates of future sea-level rise, the study warns.