Although the fact that the surface of Greenland's massive ice sheet is melting is not news, the size and speed of the melt is. NASA scientists say a melt has taken place over a larger area than has been detected in three decades of satellite observation.
Greenland's ice sheet is losing more ice than it gains, a loss that measures about 150 gigatons of ice each year. Such losses will have an effect on the level of the sea, contributing to a rise in sea level of about 3-4 millimeters per year. Dorothy Hall is a senior research scientist at NASA.