A long-coveted sea route through the arctic has opened thanks to record low sea ice coverage. Satellite images show a direct route past northern Canada – the famous Northwest Passage – is now fully navigable. And a Northeast Passage near Siberia is only partially blocked, according to the European Space Agency (press release). ESA and press reports (including the BBC, Reuters, the Guardian, AP) are implicating global warming in this. However this year’s ice retreat is extreme even by recent standards and it seems unlikely that all the blame can be laid at global warming’s door.

Sea ice this year has smashed previous records (see blog passim) and whatever its cause the opening of the Northwest Passage is likely to be as symbolic of the changing arctic as the decline of the polar bear. As the Telegraph notes, it was realised back in the 15th century that a route round the north America would improve trading routes between Europe and the Far East. A full transit was first completes in 1906, taking three years. The British Library’s history of the sea route notes:

Since Columbus encountered the land barrier of America in 1492, many explorers have ventured into the inhospitable Arctic regions in search of the Northwest Passage, a navigable channel that was believed to connect the North Atlantic and the Pacific Oceans. The search is a long chapter of failure, disaster, and tragedy, but also of heroism and endurance, and four frustrating centuries would pass before the goal would finally be achieved.

The opening of the Northwest Passage is likely to further increase the value of the arctic and the efforts of countries in the region to stake claims to the territory (as noted by Reuters, for more see Nature editorial and news story, subscription required).

Image: satellite image mosaic of arctic this month showing Northwest Passage (orange line) and Northeast Passage (blue line) / ESA