( CNN ) -- Between 1.5 trillion and 2 trillion tons of ice in Greenland , Antarctica and Alaska have melted at an accelerating rate since 2003 , according to NASA scientists , in the latest signs of what they say is global warming . This image shows the changing rate of mass in mountain glaciers on the Gulf of Alaska . Using new satellite technology that measures changes in mass in mountain glaciers and ice sheets , NASA geophysicist Scott Luthcke concluded that the losses amounted to enough water to fill the Chesapeake Bay 21 times . `` The ice tells us in a very real way how the climate is changing , '' said Luthcke , who will present his findings this week at the American Geophysical Union conference in San Francisco , California . NASA 's Gravity Recovery and Climate Experiment , or GRACE , mission uses two orbiting satellites to measure the `` mass balance '' of a glacier , or the net annual difference between ice accumulation and ice loss . `` A few degrees of change [ in temperature ] can increase the amount of mass loss , and that contributes to sea level rise and changes in ocean current , '' Luthcke said . The data reflects findings from NASA colleague Jay Zwally , who uses different satellite technology to observe changing ice volume in Greenland , the Arctic and Antarctica . In the past five years , Greenland has lost between 150 gigatons and 160 gigatons each year , ( one gigaton equals one billion tons ) or enough to raise global sea levels about .5 mm per year , said Zwally , who will also present his findings at the conference this week . GRACE measured that mountain glaciers in the Gulf of Alaska lost about 84 gigatons each year , about five times the average annual flow of the Colorado River through the Grand Canyon , according to NASA . `` Every few extra inches of sea level have very significant economic impacts , because they change the sea level , increase flooding and storm damage , '' said , Zwally , ICESat Project Scientist . `` It 's a warning sign . '' Melting ice , especially in Greenland and the Arctic , is also thought to contribute to global warming , Zwally said . When the vast ice sheets and glaciers melt , they lose their reflective power , and instead , oceans and land absorb the heat , causing the Arctic waters and the atmosphere to warm faster . `` We 're seeing the impacts of global warming in many areas of our own lives , like agriculture , '' Zwally said . As an example , he cited the pine beetle infestation of this summer in the forests of Colorado and western Canada . `` They were believed to be spreading because the winter was not cold enough to kill them , and that 's destroying forests , '' he said . In the 1990s , Greenland took in as much snow and water as it let out , Zwally said . But now , about 15 years later , sea levels are rising about 50 percent faster , making the global climate situation even more unpredictable . `` The best estimates are that sea levels will rise about 18 to 36 inches by the end of the century , but because of what 's going on and how fast things are changing , there 's a lot of uncertainty , '' he said .
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 .