Ice melt may spur inland warming
2008-06-11 11:40
Washington - If Arctic sea ice starts
melting fast, polar bears and ring seals wouldn't be the only
creatures to feel it: A study released on Tuesday suggests it
could spur warmer temperatures hundreds of kilometres inland.
That means a possible thaw in the long-frozen soil known as
permafrost, which in turn could have severe effects on
ecosystems, human infrastructure like oil rigs and pipelines
and the release of more global warming greenhouse gases in
Russia, Alaska and Canada, the scientists said.
The study is particularly pertinent because of last year's
record melt of Arctic sea ice, when ice cover in the Arctic Sea
shrank to 30% below average. Another record melt is
forecast for this year but it is unknown whether this is the
beginning of a trend.
"Our climate model suggests that rapid ice loss is not
necessarily a surprise," said David Lawrence of the National
Centre for Atmospheric Research, an author of the study.
"When you get certain conditions in the Arctic - thin ice,
a lot of first-year ice (as opposed to older, sturdier ice) -
than you can get a situation where ... you get a rapid and
steady loss over a period of five to 10 years," Lawrence said.
In such a period of rapid ice loss, autumn temperatures
along the Arctic coasts of Russia, Alaska and Canada could rise
by as much as five degrees C, the study's climate
model found. Autumn is often the warmest season in this area.
Interconnected Arctic
Last year's temperatures from August to October over land
in the western Arctic were also unusually warm, more than two degrees C above the average temperatures
for 1978-2006, raising questions about the relationship between
shrinking sea ice and warmer land temperatures.
The scientists found that when sea ice melts rapidly,
Arctic land warms three and a half times faster than the rate
predicted in 21st century climate models. The warming is
largest over the ocean but simulations indicate that it can
extend as far as 900 miles inland.
In places where permafrost is already at risk, such as
central Alaska, a quick sea ice melt could lead to a quick
permafrost thaw.
The effects of melting are already evident in parts of
Alaska, the scientists said: as pockets of soil collapse as the
ice it contains melts, highways buckle, houses are destabilised
and trees tilt crazily in a phenomenon known as "drunken
forests" when the earth beneath them gives way.
"There's an interconnectedness about the Arctic," Lawrence said.
"When sea ice retreats and retreats very rapidly it
impacts other parts of the system, like warming temperatures
over land. And warming temperatures over land can also
accelerate the degradation of permafrost, particularly
permafrost that's warm right now."
The research will be published on Friday in the journal
Geophysical Research Letters.