The Northwest Passage, the dreamed-of yet historically impassable maritime shortcut between Europe and Asia, has now fully opened up due to record shrinkage of Arctic sea ice, the European Space Agency (ESA) said on Friday.
It released a mosaic of images, taken in early September by a radar aboard its Envisat satellite, which showed that ice retreat in the Arctic had reached record levels since satellite monitoring began in 1978.
"We have seen the ice-covered area drop to just around three million square kilometres, which is about one million square kilometres less than the previous minima of 2005 and 2006," said Leif Toudal Pedersen of the Danish National Space Centre.
"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."
The most direct route of the Northwest Passage across northern Canada is "fully navigable", while the so-called Northeast Passage along the Siberian coast "remains only partially blocked," ESA said in a press release.
The previous record low was in 2005 when the Arctic area covered by sea ice was four million square kilometres. Even then, the most direct Northwest Passage did not become fully open, ESA said.
On 10 August, US Arctic specialist William Chapman of the University of Illinois Champaign-Urbana said that Arctic sea ice cover had already plunged to the lowest levels measured, 30 days before the normal point of the annual minimum.
Scientists under the UN’s Intergovernmental Panel on Climate Change (IPCC) have warned that the Arctic is one of the most vulnerable areas for global warming.
In its 4th Assessment Report issued this year, the IPCC predicted the Arctic would be virtually ice-free by mid-2070; other experts believe this could happen as soon as 2040, driven by a phenomenon called albedo.
Albedo is the reflectivity of light. Because sea ice has a bright surface, the majority of solar energy that strikes it is reflected back into space.
When sea ice melts, the dark-coloured ocean surface is exposed. Solar energy is then absorbed by the sea rather than reflected, so the oceans get warmer and temperatures rise, thus making it difficult for new ice to form.
The dramatic loss of sea ice over the past few years has prompted jockeying among countries bordering the Arctic Ocean over navigation routes and the rights to its mineral-rich seabed.