A rare, nearly ice-sheet-wide melt was recorded by satellites for the first time in 2012. The melt season was the longest it has been since satellite observations began in 1979. Melting ice contributes to sea level rise through direct, mass loss, and melt water can lubricate the underside of glaciers and accelerate glacier flow, further contributing to sea level rise. Surface melt changes the shape of ice and snow crystals, making them less reflective.The unusual melting event followed several months during which high pressure systems repeatedly parked over Greenland. High pressure generally leads to calm winds and sunny skies, both of which boost temperatures during the all-day sunshine of mid-summer at high latitudes.