Paris - European scientists voiced shock on Wednesday as they showed pictures which showed Arctic ice cover had disappeared so much last month that a ship could sail unhindered from Europe's most northerly outpost to the North Pole itself.
The satellite images were acquired from August 23 to 25 by instruments aboard Envisat and EOS Aqua, two satellites operated by the European Space Agency (ESA).
Perennial sea ice - thick ice that is normally present year-round and is not affected by the Arctic summer - had disappeared over an area bigger than the British Isles, ESA said.
Vast patches of ice-free sea stretched north of Svalbard, an archipelago lying midway between Norway and the North Pole, and extended deep into the Russian Arctic, all the way to the North Pole, the agency said in a press release.
"This situation is unlike anything observed in previous record low-ice seasons," said Mark Drinkwater of ESA's Oceans/Ice Unit.
"It is highly imaginable that a ship could have passed from Spitzbergen or Northern Siberia through what is normally pack ice to reach the North Pole without difficulty."
Spitzbergen is one of the Svalbard islands, which are Norwegian.
Drinkwater added: "If this anomaly continues, the North-east Passage, or 'Northern Sea Route' between Europe and Asia will be open over longer intervals of time, and it is conceivable we might see attempts at sailing around the world directly across the summer Arctic Ocean within the next 10 to 20 years."
The images are for late summer. In the last weeks, what was open water has begun to freeze, as the autumn air temperatures over the Arctic begin to fall, ESA said.
Regular satellite monitoring over the last 25 years shows that the northern polar ice cover has shrunk and thinned as global temperatures have risen.
But this year's images are unprecedented, and fierce storms that fragmented and scattered already thin pack ice may be to blame, the scientists believe.
The images were released less than a week after a paper, published in the US journal Science, found that year-round sea ice in the Arctic shrank by one seventh between 2004 and 2005.
Loss of sea ice does not affect global sea levels. Ice that floats in the water displaces its own volume.
However ice that is on land, as an icesheet, glacier or permanent snowcap, adds to sea level when it melts and runs off.
Retreating ice cover also creates a vicious circle, adding to the warming caused by greenhouse gases - carbon emissions, mainly from fossil fuels, that trap the Sun's heat.
Ice, being white, reflects the Sun's rays. Less ice therefore means the sea warms, which in turn accelerates the shrinkage.
The shrinkage of the Arctic icecap is viewed with alarm by scientists, as it appears to perturb important ocean currents elsewhere, notably the Gulf Stream, which gives western Europe its balmy climate.
It also threaten animals such as polar bears and seals that depend on ice.
There are geopolitical implications, too, as Canada, Russia and the United States jockey to claim rights over transpolar passages that open up within their newly ice-free waters. - Sapa-AFP