Edge of an ice shelf close to the Halley Station, Antarctica. Formation of giant icebergs is a process typical to the floating ice shelves in Antarctica. A new study indicates that an abrupt increase of basal melting may cause a substantial thinning of the large Filchner-Ronne Ice Shelf in the Weddell Sea. Photo: Ralph Timmermann / Alfred Wegener Institute

By Chris Wickham; Editing by Janet Lawrence
9 May 2012

LONDON (Reuters) – Scientists are predicting the disappearance of another vast ice shelf in Antarctica by the end of the century that will accelerate rising sea levels.

The Filchner-Ronne Ice Shelf fringing the Weddell Sea on the eastern side of Antarctica has so far not seen ice loss from global warming and much of the observation of melting has focused on the western side of the continent around the Amundsen Sea. But new research from the Alfred Wegener Institute for Polar and Marine Research in Germany says the 450,000-sq-km ice shelf is under threat.

"According to our calculations, this protective barrier will disintegrate by the end of this century," said Dr Harmut Hellmer, lead author of the study, published in the journal Nature this week.

The huge ice shelves that float on the seas fringing Antarctica provide a buffer against warming waters eating away at the base of the much larger glaciers behind them that sit on the land.

"Ice shelves are like corks in the bottles for the ice streams behind them," said Hellmer. "They reduce the ice flow.

"If, however, the ice shelves melt from below, they become so thin that the dragging surfaces become smaller and the ice behind them starts to move."

Hellmer and his team predict the melting of the Filchner-Ronne shelf could add up to 4.4 mm per year to rising global sea levels.

According to the latest estimates based on remote sensing data, global sea levels rose 1.5 mm a year between 2003 and 2010 due to melting glaciers and ice shelves, the scientists say. This is on top of an estimated 1.7 mm annual rise due to the expansion of the oceans as the water warms. […]

Professor David Vaughan of the British Antarctic Survey, who heads the Ice2sea program, told Reuters the Alfred Wegener Institute's findings add to evidence that warming oceans are having the greatest impact on the ice sheets, as opposed to atmospheric changes or the legacy of some long-term change decades or even hundreds of years ago.

"What people need to know with a sense of urgency is what is going to happen to sea levels over the next few decades," said Vaughan. "In those terms, these results are very big news indeed." [more]

New Antarctic ice shelf threatened by warming



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