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.
From TimesColonist.com
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