GREENLAND THE FASTEST MELTING AREA ON THE PLANET.

Average temperatures in the Arctic are already 3 degrees Celsius (5.4 degrees Fahrenheit) warmer than they were in 1979, according to a study published last year in the journal Nature. That increase is 4 times greater than the global average for the same time frame. Scientists say this rapid warming is the result of a feedback loop known as “Arctic amplification,” caused by dwindling ice on the sea surface. When the surface of the ocean is frozen, the bright white sea ice reflects most of the sunlight that hits it, sending two-thirds of that radiation back into space. Yet as warming waters and rising air temperatures cause sea ice to melt, more incoming sunlight is absorbed by the dark ocean surface. This warms up the water, preventing the growth of sea ice, which means the ocean gets even hotter. Relative to the 1981-2010 average, the Arctic has lost 595,000 square miles of sea ice — enough to fill the area of Texas, California, Colorado and New York combined. Sea ice also forms later in the autumn and vanishes earlier in the spring. This loss doesn’t only accelerate warming; it harms the people and animals who depend on sea ice to survive. When I was in Greenland, I spoke with residents of the remote northern town of Qaanaaq, who said that dwindling sea ice left them without a stable platform from which they could hunt and fish. Vanishing land ice — such as ice sheets and glaciers — can also create a feedback loop. But because land isn’t quite as dark as the surface of the ocean, it doesn’t cause as much additional heating. This is partly why the South Pole (which is covered by the Antarctic continent) isn’t warming as fast as the North Pole (which is surrounded by ocean). Antarctica is also protected by the vast, frigid Southern Ocean, and it’s buffered by weather patterns that prevent masses of hot air from intruding over the frozen continent.