Melt water on the Greenland ice sheet. The Greenland ice sheet (Sermersuaq in Greenlandic) is a vast body of ice covering 1,710,000 square kilometers (660,000 sq mi), roughly 80% of the surface of Greenland. The thickness is generally more than 2 km (1.2 mi) and over 3 km (1.9 mi) at its thickest point. This section of the ice sheet was photographed on the Western part, close to Ilulissat and the glacier Semeq Kujalleq. Positioned in the Arctic, the Greenland ice sheet is especially vulnerable to climate change. (Photo by: Education Images/Universal Images Group via Getty Images)