Maximum extent of Arctic sea ice, 2008-2009

The maximum occurred on February 28, in this NASA photo.

Scientists who track Arctic sea ice cover from space announced today that this winter had the fifth lowest maximum ice extent on record. The six lowest maximum events since satellite monitoring began in 1979 have all occurred in the past six years (2004-2009).

As with most NASA photos, it supersizes with a click, and it's a particularly nice image in that it clearly depicts the fabled "Northwest Passage" across the top of North America, which might open for the first time in centuries.