About 2 trillion tons of ice have melted in Greenland , Antarctica , Alaska since 2003 . Lost amount of water could fill up Chesapeake Bay 21 times , NASA scientist says . Comment: mm annually . Scientist says sea levels rising 50 percent faster than 15 years ago .
About 2 trillion tons of ice have melted in Greenland , Antarctica , Alaska since 2003 . Lost amount of water could fill up Chesapeake Bay 21 times , NASA scientist says . Most came from Greenland , where losses raised global sea levels .5 mm annually . Scientist says sea levels rising 50 percent faster than 15 years ago .