Open Waters On Northwest Passage


John Cabot's 1497 voyage in search of a northern sea route from Europe to East Asia was more than 500 years too soon. The fabled Northwest passage is opening to modern day Cabots as the Arctic's sea ice melts. Observations by the European Space Agency's CryoSat-2 satellite suggest that the route may be ready for summer sea traffic sooner than expected.

The satellite found that 900 cubic kilometers of summer sea ice melted during the past year, a rate 50 percent higher than many climate change forecasts predicted, reported the Guardian.

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"Very soon we may experience the iconic moment when, one day in the summer, we look at satellite images and see no sea ice coverage in the Arctic, just open water," Seymour Laxon of University College London, where CryoSat-2 data is being analyzed, told the Guardian.

The CryoSat-2 is the first scientific instrument capable of accurately and consistently measuring sea ice thickness from space. Previous measurements could only measure the area covered by sea ice or gave only spotty observations of thickness. With the CryoSat-2 data, climate scientists can see that the ice is not just shrinking in extent, but what remains of it is thinner. For example, in northern Canada and Greenland summer ice coverage has dropped from five to six meters (16-20 feet) thick to between one and three meters (3 to 10 feet).

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The accuracy of CryoSat-2's measurements were cross-checked with ground measurements, data from underwater sonar stations and observations from airplanes.

"We can now say with confidence that CryoSat's maps of ice thickness are correct to within 10 cm," Laxon said.

Although the overall trend is downward, the good news is that the ice makes an aggressive recovery in winter. Winter sea ice coverage has not decreased as rapidly as summer sea ice. Laxon suggests that means ice is reforming faster in the winter than it did in the past.


Sea ice in Baffin Bay in the Arctic (Brocken Inaglory, Wikimedia Commons)

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