http://seattlepi.nwsource.com/national/145267_arctic24.html
Friday, October 24,
2003
Researchers
fear decline in sea ice is changing climates
By LEE BOWMAN
SCRIPPS HOWARD NEWS
SERVICE
WASHINGTON -- NASA
scientists released new evidence yesterday
that the Arctic region is warming up and its sea ice cover is
diminishing, with implications for further climate change worldwide.
Satellite data show
that compared with the 1980s, surface temperatures
across most of the Arctic warmed significantly in the last decade,
with the biggest temperature increases occurring over North America.
When compared with
ground-based surface temperatures, the rate of
warming in the Arctic between 1981 and 2001 was eight times the
rate
of warming over the last 100 years, said Josefino Comiso, a senior
research scientist at NASA's Goddard Space Flight Center who compiled
the data. "The Arctic is in the process of being transformed,"
he said.
"Previously, similar
studies used data from very few points scattered
in various parts of the Arctic region," said Comiso, whose
work will
be published Nov. 1 in the American Meteorological Society's Journal
of Climate. "These results show the large spatial variability
that
only satellite data can provide."
The data came from
thermal infrared images taken by polar-orbiting
satellites run by the National Oceanic and Atmospheric Administration.
Researchers found that
warming is prevalent over most of the
Arctic -- some areas bucked the trend, such as Greenland,
where temperatures appear to be cooling by about 0.2 degrees
per year. Springtime arrived earlier and was warmer, while
warmer autumns lasted longer. Temperatures increased by an
average of just over 2 degrees Fahrenheit per decade over
sea ice during Arctic summers.
Another NASA-funded
researcher, Mark Serreze of the University
of Colorado-Boulder, reported yesterday that the extent of Arctic
summer sea ice in 2002 reached the lowest level ever recorded
by satellites.
"It appears that
the summer of 2003, if it does not set a new
record, will be very close to the levels of last year," Serreze
said. "How much of this warming is due to natural fluctuations
and how much is caused by human activity, we don't really know.
But the fact is, the climate is changing, and in the Arctic
it is changing rapidly."
Last month, U.S and
Canadian researchers reported the Arctic's
largest ice shelf, the 270-square mile Ward Hunt Ice Shelf along
the north shore of Ellesmere Island, had fractured for the first
time in several thousand years, draining a freshwater lake that
it had contained and raising the prospect that it could break
into large icebergs like those seen from disintegrating Antarctic
ice shelves.
And a team of Chinese
scientists who completed a 74-day Arctic
expedition in September found that the thickness of the sea ice
now averages 8.8 feet, down from an average of more than 15 feet
in the 1980s.
Beyond having more
open water and accelerating local changes,
such as erosion, in the Arctic, warming trends and changes
in ice cover could greatly affect ocean climate processes,
said Michael Steele, an oceanographer at the University of
Washington.
Liquid water absorbs
more of the sun's energy than ice.
That means the Arctic
could get even warmer, and even more
ice could melt. Steele said such dynamics could change the
temperature of ocean layers; alter ocean circulation,
which can affect weather worldwide; change marine habitats;
and affect shipping.
###
