Ice loss from Arctic mountain glaciers, ice caps and the Greenland Ice Sheet
There are 2930000 km3 of ice locked up in the Greenland Ice Sheet, and about 250 000 km3 in ice caps and mountain glaciers in the Arctic. If they were all to melt, global sea level would rise by an estimated 7.9 m. Several sources of evidence indicate that these giant chunks of ice are diminishing in size as temperatures rise, although they are not expected to vanish altogether in the near future. It would take thousands of years for the Greenland Ice Sheet to melt entirely.
Ice loss has been measured using mass budget, surface altimetry, changes in gravity. As well as these methods, maps, aerial photographs and satellite images can be compared to show how areas covered by ice caps and glaciers have changed over time.