Area of surface melting across the Greenland Ice Sheet, as inferred from satellite observations

Increased melting of the large polar ice sheets contributes to the observed increase in sea level. Observations of the area of the Greenland ice sheet that has been at the melting point temperature at least one day during the summer period shows a 50% increase during the period 1979 to 20086 (see figure). The Greenland region experienced an extremely warm summer in 2007. The whole area of south Greenland reached the melting temperatures during that summer, and the melt season began 10-20 days earlier and lasted up to 60 days longer in south Greenland.

Climate Change: Global Risks, Challenges & Decisions