The unexpectedly big increase adds to fears the ice sheet is vulnerable to thawing. West Antarctica holds enough ice to raise world sea levels by at least 3.3 meters (11 feet) if it ever all melted.
The warming raises further concerns about the future contribution of Antarctica to sea level rise. Higher summer temperatures raised risks of a surface melt of ice and snow even though most of Antarctica is in a year-round deep freeze.
Low-lying nations from Bangladesh to Tuvalu are especially vulnerable to sea level rise, as are coastal cities from London to Buenos Aires. Sea levels have risen by about 20 cms (8 inches) in the past century.
The United Nations panel of climate experts projects that sea levels will rise by between 18 and 59 cms this century, and by more if a thaw of Greenland and Antarctica accelerates.
The rise in temperatures in the remote region was comparable to that on the Antarctic Peninsula to the north. Parts of the northern hemisphere have also warmed at similarly fast rates.
Several ice shelves - thick ice floating on the ocean and linked to land - have collapsed around the Antarctic Peninsula in recent years. Once ice shelves break up, glaciers pent up behind them can slide faster into the sea, raising water levels.
The Pine Island glacier off West Antarctica, for example, brings as much water to the ocean as the Rhine river in Europe.
West Antarctica now contributes about 0.3 mm a year to sea level rise, less than Greenland's 0.7 mm. The bigger East Antarctic ice sheet is less vulnerable to a thaw. Read more...