Source: The Economist
ON SEPTEMBER 16th 2012, at the height of the summer melt, the Arctic Ocean’s ice sheet had shrunk to an area of 3.41m square kilometres (1.32m square miles), half what it was in 1979. And its volume had shrunk faster still, to a quarter of what it was in 1979, for the sheet is getting thinner as well as smaller. One culprit is global warming, which is fiercer at the poles than elsewhere. The world’s average temperature in 2012 was nearly 0.5°C above the average for 1951-80. In the Arctic, it was up almost 2°C.