About 1 trillion tons of ice have melted in Greenland , Antarctica , Alaska since 2003 . In the 1990s , Greenland took in as much snow and water as it let out , Zwally said . This amount of water could fill up Hudson Bay 21 times , NASA scientist says . Most came from Greenland , where losses raised global sea levels .5 percent annually . Scientist says sea levels rising 50 percent faster than 100 years ago .
About 1 trillion tons of ice have melted in Greenland , Antarctica , Alaska since 2003 . This amount of water could fill up Hudson Bay 21 times , NASA scientist says . Most came from Greenland , where losses raised global sea levels .5 percent annually . Scientist says sea levels rising 50 percent faster than 100 years ago .