ABSTRACT
The Greenland Ice Sheet is changing rapidly in response to climate warming. Even though snowfall slightly increased in the interior, coastal regions are melting and sliding to the sea faster than before, which causes sea level to rise. Between melting, snowfall and faster sliding, the acceleration of glaciers to the sea contributes two-thirds of the mass loss; that is, it dominates the ice sheet response to climate warming. Over the last decade, the mass deficit of the ice sheet doubled, and in 2005 it exceeded 200 cubic kilometers of ice per year (50 cubic miles per year), a rate that would be sufficient to raise sea level by 0.6 mm per year (0.25 inches per year). Because warming will cause more glaciers to speed up and ice will continue to thin further inland, this rate of mass loss will increase as climate continues to warm. Global climate models project roughly 1–2 ft of sea level rise by 2100, but these models do not include a complete description of glacier mechanics and cannot explain current observations. At present, we do not have models capable of predicting the future state of the Greenland Ice Sheet. Other considerations, based on air temperature and paleoclimatic evidence, suggest that sea level could rise by as much as 1–3 m (3–10 ft) by 2100.
