Monday, January 9, 2012

Three Russian Rivers Freshen Arctic Ocean by Randy Boswell, Postmedia News

A team of U.S. scientists appears to have solved a mystery about the freshening of the Arctic Ocean off the north coast of Canada, tracing the source of the un-salted water that's been building up in recent years in the Beaufort Sea to the discharge from three great rivers in Russia.

The finding, detailed this week in the journal Nature, is considered key to gauging how the polar region is changing in an era of retreating sea ice linked to global climate change.

"Knowing the pathways of freshwater in the upper ocean is important to understanding global climate because of freshwater's role in protecting sea ice - it can help create a barrier between the ice and warmer ocean water below - and its role in global ocean circulation," said University of Washington scientist Jamie Morison, lead author of the study.

"Too much freshwater exiting the Arctic would inhibit the interplay of cold water from the poles and warm water from the tropics."

Among the theories about the unusual freshening of the Beaufort Sea was that the melting ice cover in the region - including extreme retreats in the past decade - was largely responsible. That and other ideas were tested by a Morison-led team of researchers from the University of Washington and NASA's Jet Propulsion Laboratory in California.

The scientists combined analysis of water samples collected throughout the ocean with data from the NASA satellites ICESat and GRACE.

"Changes in the volume and extent of Arctic sea ice in recent years have focused attention on the impacts of melting ice," said NASA scientist Ron Kwok, a leading monitor of ice conditions in the Arctic.

He noted in the summary that the satellite data allowed researchers "to now examine the impacts of widespread changes in ocean circulation."

That line of research led to the conclusion that water from three major Russian rivers - the Lena, Yenisey and Ob - is the chief source of the Beaufort Sea freshening, with a recent change in Arctic Ocean circulation causing the Eurasian river discharges to be pumped away from Russia and to collect off the north coast of western North America.

But while the Beaufort Sea is fresher today than it has been for 50 years, the team concluded, the change has been offset by increased salinity in the Eurasian Basin.

That finding is deemed significant because it discounts the idea that the overall Arctic Ocean is becoming fresher as a result of melting ice and changes in sea water circulation.

"The freshening on the Canadian side of the Arctic over the last few years represents a redistribution of freshwater," Kwok said.

"There does not seem to be a net freshening of the ocean." shot through the eye remained "oblivious" to her injury and her friend's dead body beside her and instead concentrated on finishing her beer, a source says. Justice sources say it was nothing short of a miracle the 30-year-old woman didn't become the city's 40th homicide victim of 2011. Police and paramedics arrived inside a Winnipeg home in the early hours of Dec. 31 to find the woman calmly sitting in a chair. The woman was severely impaired, and seemed to be showing no discomfort despite the obvious injury she suffered.

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