Study Finds Climate
Change May Melt Permafrost
December 27, 2005 — By Associated Press
ANCHORAGE, Alaska — Climate change
could melt the top 11 feet of Alaska permafrost by the end of the
century, according to a new study.
The federal study applied one supercomputer climate models to the future
of permafrost.
Under the most extreme scenario outlined, warming temperatures could
thaw the top 11 feet of permafrost near the ground surface in most areas
of the Northern Hemisphere by 2100, altering ecosystems across Alaska,
Canada and Russia.
"If that much near-surface permafrost thaws, it could release
considerable amounts of greenhouse gases into the atmosphere, and that
could amplify global warming," said lead author David Lawrence, with the
National Center for Atmospheric Research. "We could be underestimating
the rate of global temperature increase."
A permafrost researcher at the University of Alaska Fairbanks, however,
disagrees that the thaw could be so large. Alaska's permafrost won't
melt that fast or deep, said Vladimir Romanovsky, who monitors a network
of permafrost observatories for the Geophysical Institute.
If air temperatures increase 2 to 4 degrees over the next century,
permafrost would begin thawing south of the Brooks Range and start
degrading in some places on Alaska's Arctic slope, he said. But a
prediction that melting will reach deeply over the entire region goes
too far, he said.
The computer climate model didn't consider some natural factors that
tend to keep the permafrost cold, Romanovsky said. For example, deeper
permafrost, largely untouched by recent warming at the surface, would
have an influence.
Lawrence said he hopes to collaborate with Romanovsky to fine-tune
future studies to deal with those deeper layers.
Permafrost -- earth that remains frozen year-round -- lies under much of
Alaska, Canada and Siberia. It can be more than 1,000 feet deep on the
Arctic slope.
Ground melting is only one clue that Arctic climate change may be
speeding up. In September, the polar ice cap shrank to its smallest
extent in 25 years of monitoring by satellite. Tundra has been greening
up. NASA recently reported that 2005 may top 1998 as the Earth's warmest
year on record.
The permafrost simulations came from some of the most detailed climate
models ever made, Lawrence said. Using supercomputers in the United
States and Japan, it calculated how frozen soil would interact with air
temperatures, snow, sea ice changes and other processes.
The study was published Dec. 17 in the journal Geophysical Research
Letters and presented earlier in the month at a science conference in
San Francisco.
Source: Associated Press
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