Northern sea ice takes a big
hit in 2007
By Ned Rozell
December 17, 2007
SAN FRANCISCO - For the past few years, vanishing northern sea
ice has been a theme of many talks and posters here at the fall
meeting of the American Geophysical Union, which draws about
15,000 scientists to the Moscone Center during the weeklong conference.
At a press conference here on Wednesday, Dec. 12, 2007, scientists
revealed that the ice on top of the northernmost ocean took a
punch in the summer of 2007 that might be a knockout blow.
In 1980, the dense ice that floats on the Arctic Ocean like a
large, moving jigsaw puzzle took up about the same area as the
entire Lower 48 states; in September 2007, it was about as big
as the U.S. east of the Mississippi River, said Don Perovich
of the U.S. Army Cold Regions Research and Engineering Laboratory
in New Hampshire. The ice loss in 2007, 23 percent greater than
the previous record in 2005, has some scientists here predicting
that the northern sea ice will vanish in summer as soon as five
years from now. Perovich agreed that one of the greatest environmental
changes people have ever seen might be close at hand.
Sea ice off Gambell,
Photo by Ned Rozell.
"I used to say that sometime in my children's lifetimes
(sea ice covering the Arctic Ocean would disappear for half the
year), but now I might see it," said Perovich, who is in
John Walsh of the International Arctic Research Center in Fairbanks
was, along with Perovich, one of four scientists facing reporters
from all over the world on Wednesday morning. Walsh spoke of
how warmer water from the Atlantic has been entering the Arctic
"We're really moving into record territory in the last four
or five years," Walsh said, citing the work of IARC's Igor
Polyakov, who coordinates an annual scientific cruise in the
While surprisingly warm water from the Atlantic is entering the
Arctic Ocean-which probably adds to the loss of sea ice by melting
it from beneath-unusually warm water from the Pacific is also
invading the Arctic Ocean through the Bering Strait, said Mike
Steele of the University of Washington.
"In 2007, north of Alaska and eastern Siberia, the Arctic
Ocean was 3.5 degrees Celsius warmer than the historical average
and 1.5 degrees warmer than the historical maximum," Steele
said, adding that waters off Alaska were especially warm. "The
Bering Strait and Chukchi Sea are warming most."
Because ice reflects about 85 percent of the sun's radiation
and open water only reflects 7 percent, 2007's low ice led to
the ocean absorbing much more of the sun's heat. Perovich calculated
that the Arctic Ocean in September 2007 absorbed 300 percent
more solar energy than it did in 1980. He said that the sun was
the real culprit in the loss of sea ice this year, and that the
warm pulses of Atlantic and Pacific water also eroded the ice
Perovich and his colleagues monitored a piece of sea ice off
Alaska's coast on the Beaufort Sea this year, finding it was
almost 11 feet thick in June but shrunk to less than two feet
thick by September. Ice seems to be at least three feet thinner
than normal almost everywhere scientists have measured it.
"That missing meter of ice means the ice is more vulnerable,"
The loss of ice in the summer will happen soon unless things
change drastically, the scientists said.
"As you go further down this path, it's harder to get back,"
Perovich said. "It's the fourth quarter now, and we're down
For all the dire predictions that would spell the doom of the
polar bear and other creatures that depend on sea ice, the sea
ice could still bounce back, Steele said.
"Ice grows quickly when the air is really cold," he
said. "A recipe to bring the ice back is a few cold winters
in a row.
This column is provided
as a public service by the Geophysical
University of Alaska Fairbanks, in cooperation with the UAF
Ned Rozell [ firstname.lastname@example.org
] is a science writer at the institute.
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