| Floes
may be just moving around in Arctic winds Bob Weber The Canadian
Press  | | File
Photo / Open water, shown in this photo taken at the North Pole in early August
by Malcolm C. McKenna, a paleontologist at New York's American Museum of Natural
History, was interpreted as a sign that global warming is melting the total volume
of ice at the North Pole. But that claim has been disputed by a Canadian scientist
at an international meeting of Arctic scientists in Iqaluit, Nunavut. |
A
Canadian scientist is pouring cold, unfrozen water on the notion that global warming
is melting arctic sea ice like a Popsicle at the beach.
Greg Holloway
galvanized an international meeting of Arctic scientists Tuesday by saying there
is little evidence of a rapid decline of the volume of ice in the northern oceans.
Despite breathless media reports and speculation of an ice-free Northwest
Passage, he suggests that it's far more likely that the ice has just been moved
around in the cycles of Arctic winds.
"It's more complicated than we thought,"
said Holloway, a scientist with the Institute of Ocean Science in Victoria.
The
original theory was based on declassified records from the trips of U.S. submarines
under the ice.
Satellite pictures have clearly shown that the surface
area of the ice has decreased about three per cent a year for the last 20 years.
But the question was, How thick was it?
The sub data generated
headlines and cover stories from the New York Times to Time Magazine when it seemed
to indicate that ice volume had decreased by 43 per cent between 1958 and 1997.
The evidence seemed good. There were only eight different voyages, but
they had generated 29 different locations across the central Arctic where there
were enough readings to make comparisons.
Holloway, however, couldn't
make that conclusion jibe with any of his computer models.
"We couldn't
understand how the reduction could be so rapid," he said.
"My first thought
was, 'What is it we don't understand?' ''
Holloway knew that there was
a regular pattern of sea ice being blown into the North Atlantic. He decided to
examine if the wind patterns across the circumpolar North could have had something
to do with the missing ice.
Wind patterns blow across the Arctic in a
50-year cycle.
At different points in the cycle, ice tends to cluster
in the centre of the Arctic. At other points, the ice is blown out to the margins
along the Canadian shore, where the subs were not allowed to go due to sovereignty
concerns.
When Holloway lined up the sub visits with what he knew about
the wind cycles, the explanation for the missing ice became clear: "The submarine
sampled ice during a time of oscillation of ice toward the centre of the Arctic.
They went back during a time when ice was oscillating to the Canadian side." He
had found the missing ice.
"I believe it is most probably explained with
the shifting ice within the Arctic locations," he said to applause from scientific
delegates from Norway to China.
If the submarines had made their first
visit one year earlier and their return one year later, Holloway says they would
have found no change in the thickness of the sea ice at all.
But he cautions
that his research doesn't force a total re-evaluation of the theory of global
warming. Temperatures on average are rising around the world, he says.
It
does, however, deflate excitement about the possibility of an ice-free Northwest
Passage.
The chance of a year-round northern shipping route has thrilled
commercial shippers but worried environmentalists.
"At this time, we do
not have the basis to predict an open Northwest Passage," said Holloway.
It
also calls into question some of the findings and recommendations of the International
Panel on Climate Change, which accepted the 43-per-cent hypothesis in its report
to governments.
More data is coming in as further reports from American
and British subs are released. But the furore over the first results contains
a lesson for both scientists and the public, Holloway says.
"It's a very
small amount of time and a very limited number of places those submarines could
go," he said.
"The cautionary tale to all this is the oversimplifying
of a big and complex system.
"Who knows what's going on out there?" |
