Sea ice and climate change

One of the harbingers of global — the extent of the Arctic sea ice — has passed a new threshold. German researchers announced on Sept. 8 that the sea-ice cover had shrunk below its record minimum, set in 2007.
The NSIDC proclaimed  on Sept. 16, 2007, when it measured the extent of the ice at 1.59 million square miles (4.13 million square kilometers), about 1 million square miles (2.69 million square kilometers) below the average for 1979 to 2000. NSIDC scientists said the 2007 record was the result of a perfect storm — including fewer clouds that allowed sunlight to melt the ice, and winds that shoved the ice together — that brought the ice to a new minimum. While temperatures were warm this year, other conditions were more typical.