Permafrost—the frozen soil that forms the backbone of the Arctic tundra—is melting due to climbing global temperatures. In Alaska, the mercury may rise by 1 to 5 degrees Celsius (1.8 to 9 degrees Fahrenheit) by 2100. In this false-color image of Alaska's North Slope, taken by NASA's Terra satellite, the blue-black color shows the many ponds of meltwater that collected on the coast in July 2007. Photograph courtesy Goddard Space Flight Center