During the summer of 2012 the Arctic ice sheet shrank to 1.39 million square miles, less than 50 percent of its average minimum since 1979 and about 18 percent smaller than the previous record, set in 2007. The next four lowest-ice seasons occurred between 2007 and 2012. Summer ice is disappearing decades faster than predicted, hastening the rise of sea levels. Obama entered office with ambitions to clinch an international climate change treaty and push through cap and trade legislation. Both efforts failed. The administration did increase gas mileage standards—to 54.5 mpg by 2025—and proposed a rule capping power plant emissions. This will reduce pollution without slowing global warming. For that, the U.S. will need far more aggressive goals, shared with the rest of the world.
 
Sources: National Snow & Ice Data Center, U.S. Environmental Protection Agency

Photographs by David Brandon Geeting for Bloomberg Businessweek