Spring Thaw on the North Slope

This false-color satellite image released by NASA shows the re-emergence of hundreds of ponds scattered across the tundra of Alaska’s North Slope after the winter snows disappeared in early June. The region depicted in the image is roughly 250 kilometers (155 miles) across and is located south of Barrow. The image vividly illustrates just how much of the Arctic tundra is made up of ponds and small lakes, which often form because melting snows are unable to penetrate more than a foot or two into the earth because the permafrost below is frozen year-round. The relative flatness of the terrain also slows drainage and promotes the formation of ponds and lakes. As the climate warms, the permafrost is beginning to thaw in many areas, leading to the draining of some lakes. In other areas, however, the layer of permafrost is actually thickening. Overall, soil temperatures in Arctic tundra are rising, leading to increased release of methane, a powerful greenhouse gas.