PARIS - Arctic ice coverage has receded to record lows, the European Space Agency said, raising the prospect of greater maritime traffic through the long-sought waterway known as the Northwest Passage.
Satellite images this week showed Arctic ice cover fell to the lowest level since scientists started collecting such information in 1978, according to a statement on the agency's website Saturday.
Many experts believe global warming is to blame for melting the passage. The waters are exposing unexplored resources, and vessels could trim thousands of kilometres from Europe to Asia compared with the current routes through the Panama Canal.
According to one estimate, the Northwest Passage is 7,000 kilometres shorter than the 23,000-kilometre Panama Canal route. It is also shorter than the 21,000-kilometre Suez Canal route to Asia.
Ice has retreated to about three million square kilometres, Leif Pedersen of the Danish National Space Centre, said in the statement. ESA said the previous low was four million square kilometres back in 2005.
"There has been a reduction of the ice cover over the last 10 years of about 100,000 square kilometres per year on average, so a drop of one million square kilometres in just one year is extreme,'' he said.
Ice levels in the Arctic ebb and flow with the seasons, allowing for intermittent traffic between Europe and Asia across northern Canada -- a route explorers and traders have long dreamt could open fully.
Environmentalists fear increased maritime traffic and efforts to tap natural resources in the area could one day lead to oil spills and harm regional wildlife.
Pedersen said the extreme retreat this year suggested the passage could fully open sooner than expected -- but ESA did not say when that might be. Efforts to contact ESA officials in Paris and Noordwik, Netherlands, were unsuccessful.
Until now, the passage has been expected to remain closed even during reduced ice cover by multiyear ice pack -- sea ice that remains through one or more summers, ESA said.
With ice levels shrinking, some countries have jockeyed for claims over the passage under the North Pole, which is also a potential oil-producing region.
The race heated up last month when Russia sent two small submarines to plant a tiny national flag under the North Pole in August, and Canada announced plans to build a new army training centre and a deep-water port in the North.
Denmark, Norway and the United States also have claims in the vast region.
Under international law, the five countries control an economic zone within 320 kilometres of their continental shelf. But the definition of the limits of that shelf are in dispute.
Researcher Claes Ragner of Norway's Fridtjof Nansen Institute, which works with environmental and political issues over the Arctic, said that, for the time being, the new opening has only symbolic meaning for the future of sea transport.
"Routes between Scandinavia and Japan could be almost halved, and a stable and reliable route would mean a lot to certain regions,'' he said by telephone.
But even if the passage is opening up and polar ice continues to melt, it will take years for such routes to be practicable, according to Ragner.
"It won't be ice-free all year around and it won't be a stable route all year,'' he said. "The greatest wish for sea transportation is streamlined and stable routes.''
"Shorter transport routes means less pollution if you can ship products from A to B on the shortest route, but the fact that the polar ice is melting away is not good for the world in that we're losing the Arctic and the animal life there,'' Ragner added.
Arctic sea ice naturally extends its surface coverage each winter in the Northern Hemisphere, and recedes each summer, ESA said, but the overall loss has increased since satellite records were begun in 1978.
The opening observed this week was not the most direct waterway, ESA said. That would be through northern Canada along the coast of Siberia, which remains partially blocked.
