The most direct shipping route from Europe to Asia is fully clear of ice for the first time since records began, the European Space Agency (Esa) says.
Historically, the Northwest Passage linking the Atlantic and Pacific Oceans has been ice-bound through the year.
But the agency says ice cover has been steadily shrinking, and this summer's reduction has made the route navigable.
The findings, based on satellite images, raised concerns about the speed of global warming.
BBC News website, 10th September 2000:
A Canadian police patrol boat has completed a voyage through the fabled Northwest Passage without encountering any pack ice.
Most of the passage along the coast of Alaska and Canada lies north of the Arctic Circle and scientists say that the absence of ice may be further evidence of global warming.
UPDATE: Hello to people clicking through from climateaudit.org. This link provides the main context. Turns out the North West Passage has been navigated in 1906, 1942, 1944, 1977, 2000 and 2005.