(http://msnbcmedia.msn.com/j/MSNBC/Components/Photo/_new/121223-antarctica-hmed-3p.photoblog600.jpg)Alister Doyle / Reuters fileClimate change is turning Antarctica's ice into one of the biggest risks for coming centuries, scientists say. By ReutersWest Antarctica is warming almost twice as fast as previously believed, adding to worries of a thaw that would add to sea level rise from San Francisco to Shanghai, a study showed on Sunday.
Follow @NBCNewsWorld (https://twitter.com/NBCNewsWorld) Annual average temperatures at the Byrd research station in West Antarctica had risen 2.4 degrees Celsius (4.3 Farenheit) since the 1950s, one of the fastest gains on the planet and three times the global average in a changing climate, it said.
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, a process that would take centuries.
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