The summer of 2012 brought Greenland far more extensive melt than anything observed in the satellite record: in July 2012, surface melt extended over nearly the entire ice sheet. The standardized melt index was nearly double the previous record.

Shallow melt ponds on the surface of consolidated sea ice act as skylights that promote massive under-ice phytoplankton blooms. These under-ice blooms may boost estimates of Arctic phytoplankton productivity by a factor of 10.

Arctic sea ice extent set a new record low at the end of the summer melt season on September 16, 2012. But extent is not the only quality of the ice that is changing. Wind and ocean circulation patterns are conspiring with a warmer climate to reduce the amount of year-round (multi-year) ice, transforming the remaining ice into a younger, thinner version of its old self.

Arctic sea ice extent fell to 1.58 million square miles on August 26, 2012. This was 27,000 square miles smaller than the previous record low of 1.61 million square miles set in 2007.

In September 2011, Arctic sea ice reached its second-lowest minimum extent in the satellite record.

Data from 2010 indicate that mountain glaciers predominantly lost mass, and preliminary data from 2011 indicate a continuation of the same long-term trend.

In 2011, annual snow cover extent over Northern Hemisphere continents (including the Greenland ice sheet) averaged 24.7 million square kilometers, which is 0.3 million square kilometers less than the long-term average.

Pages