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Scientists calculate sea level rise if Antarctic ice shelves collapse

"We should view these dramatic changes in the Antarctic Peninsula as a warning signal for the much larger ice sheet-ice shelf systems elsewhere," said researcher Nicholas Barrand.

Scientists have calculated the rise in seas that would result from the collapse of two of Antarctica's most vulnerable ice shelves.

Much attention has been paid to the Larsen C ice shelf, as its breakdown has been most visible -- and well documented. But the latest research, published this week in the journal The Cryosphere, suggests the collapse of Larsen C would contribute just a few millimeters to global sea level rise.

Scientists determined the collapse of the smaller George VI ice shelf would trigger approximately five times the amount of sea level rise, about 22 millimeters.

"These numbers, while not enormous in themselves, are only one part of a larger sea-level budget including loss from other glaciers around the world and from the Greenland, East and West Antarctic ice sheets," Nicholas Barrand, a glaciologist at the University of Birmingham, said in a news release. "Taken together with these other sources, the impacts could be significant to island nations and coastal populations."

Because ice shelves like Larsen C and George VI act like dams, slowing the flow of inland ice toward the coast, understanding their structural integrity is essential to forecasting the loss of Antarctic ice.

In 2002, Larsen C's neighbor, the Larsen B ice shelf, disintegrated in a matter of wakes after a massive iceberg broke away. Last year, an iceberg measuring 2,239 square miles long and weighing more than 1 trillion metric tons broke away from the Larsen C ice shelf.

  Though the breakdown of Larsen C is likely to be dramatic, the latest analysis showed the disintegration of George VI would have a greater impact on the flow of inland ice toward the sea.

"The vulnerability to change at George VI ice shelf and the possible sea level implications from these changes, are far greater," said British Antarctic survey scientist Clemens Schannwell.

The collapse of George VI would trigger greater sea level rise because the glaciers it backstops are significantly larger than those that flow into Larsen C.

Future analysis of Antarctica's ice shelves can help scientists more accurately estimate the impacts of global warming on ice loss and the impacts of ice loss of global sea levels.

"In light of the increasing temperatures projected for the coming century, the Antarctic Peninsula provides an ideal laboratory to research changes in the integrity of floating ice shelves," Barrand said. "This region can tell us about ice shelf processes and allow us to observe the response of inland ice to ice-shelf changes. We should view these dramatic changes in the Antarctic Peninsula as a warning signal for the much larger ice sheet-ice shelf systems elsewhere in Antarctica with even greater potential for global sea-level rise."

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