Arctic ice has melted enough again this summer for the legendary Northwest Passage to open up, according to the National Snow and Ice Data Center. It's the third time in history – and the third straight year – that both the Northwest and Northeast Passages are open due to a lack of Arctic ice.
The center reports both passages are largely free of ice, allowing the potential for a circumnavigation of the Arctic Ocean. At least two expeditions are attempting this feat, the Norwegian explorer Borge Ousland and the Peter I yacht from Russia.
On September 3, Arctic ice extent fell below the seasonal minimum for 2009 to claim third-lowest on record. The minimum ice extent for the year will probably occur in the next two weeks.
The summer melt season usually begins in March and ends sometime during September, according to the ice data center. The annual cycle of melting and freezing Arctic sea ice has been measured since 1979.
Finding the fabled Northwest Passage through the Arctic had been a goal of mariners for centuries.
The first recorded attempt to find and sail the Northwest Passage occurred in 1497, and ended in failure, reports meteorologist Jeff Masters on the Weather Underground's Wunderblog. The thick ice that choking the waterways thwarted all attempts at passage for the next four centuries.
Masters believes that the last time the Northwest Passage was open for multiple years may have been as far back as 6,000 to 8,500 years ago, when the Earth's orbital variations brought more sunlight to the Arctic in summer than now.