Support WBURTrying To Unravel The Mysteries Of Arctic WarmingPlay05:01Download AudioRichard HarrisAugust 20, 2011 ShareAn iceberg is seen melting off the coast of Ammasalik, Greenland, in July 2007. This year, scientists say sea-ice extent in the Arctic has reached its lowest level since monitoring by satellite began in 1979, the result of rising temperatures. (AP)
