* Shrinking of ice extent faster than expected
* Affects planning by indigenous peoples, investors
By Alister Doyle and Nina Chestney
OSLO/LONDON, Aug 30 Ice on the Arctic Ocean
could vanish in summertime as early as 2015 or linger for many
decades after a thaw to a record low this month that is widely
blamed on climate change, according to scientists.
Huge variations in climate experts' predictions complicate
long-term plans by everyone from indigenous peoples who depend
on ice for hunting to shipping firms hoping for new trans-Arctic
shipping routes and oil firms seeking new areas for drilling.
Most computer models of climate change indicate the ice
could disappear in summer in 30 to 40 years, said Lars-Otto
Reiersen, head of the Arctic Monitoring and Assessment
"But there are models that indicate 2015 as an extreme," he
A precipitous decline in the extent of the ice in recent
years has outpaced projections by a U.N. panel of experts in
2007 that indicated a near-complete loss in summer by the end of
Peter Wadhams, a professor of ocean physics at Cambridge
University, said that a prediction he made in 2008 that the ice
could be gone in 2015 because of global warming was looking
"It could even all go this summer," he said. "So I think the
2015 date is now looking a bit conservative. We may end up
having an ice-free summer before then."
He said that the thickness of the ice - not just the extent
floating on the sea that many researchers focus on - had
declined unexpectedly quickly. That meant the volume of ice was
down to about 30 perent of its amount three decades ago.
The ice shrank to its lowest extent since satellite
monitoring began in the late 1970s at 4.10 million square km
(1.58 million square miles) on Aug. 26, according to the
National Snow and Ice Data Center (NSIDC).
The melt, below the minimum extent set in 2007, may continue
well into September.
The shrinking ice itself can stoke climate change. As the
white, reflective ice retreats, it opens up darker water that
soaks up more and more heat, adding to global warming caused by
a build-up of greenhouse gases.
"If it shrinks to zero you are decreasing the albedo
(reflected sunlight) of the Earth. That's the same warming
effect of 25 years of additional carbon dioxide," Wadhams said.
Most experts are more cautious about the pace.
A study this weekend in the journal Geophysical Research
Letters, whose authors included NSIDC experts, said that some
models projected virtually ice-free conditions by 2020, others
by the end of the century.
"A seasonally ice-free Arctic Ocean within the next few
decades is a distinct possibility," they concluded.
"We just don't know exactly why this is moving so fast,"
said Robert Corell, head of the Global Environment Technology
Foundation based in Arlington, Virginia. He said that he
believed that the ice would probably last into about the 2030s.
The shrinking ice, also affecting wildlife such as polar
bears, does not just influence the sea. Ward Hunt Lake at the
northern tip of Arctic Canada had a permanent ice cap that was
measured as 4.2 metres thick in the summer of 1953.
"Last year we observed the disappearance of all of the ice
and the lake had open water for the first time in recorded
history," said Warwick Vincent, director of the Centre for
Northern Studies at Laval University in Quebec.
The sea ice freezes out again in September, reaching a
maximum towards the end of the northern winter in March.
A related problem to thickness is that there is little of
the hardest ice that survives several seasons. And ocean
currents and winds may be changing, bringing warmer water and