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Researchers at the University of Colorado at Boulder have
found that the extent of Arctic sea ice, the floating mass
of ice that covers the Arctic Ocean, is continuing its rapid
decline.
Artic Sea Ice in the winter of
1950. Courtesy of NOAA.
The latest satellite information indicates the September
2004 sea ice extent was 13.4 percent below average, a reduction
in area nearly twice the size of Texas, said Mark Serreze
of CU-Boulder's National Snow and Ice Data Center, or NSIDC.
In 2002, the decline in arctic sea ice during September --
which traditionally marks the end of the summer melt season
-- was about 15 percent, a record low, said CU-Boulder researcher
Walt Meier of NSIDC. The decline in sea ice extent during
September has averaged about 8 percent over the past decade,
said Serreze, who is part of a CU-Boulder team monitoring
Arctic sea-ice conditions. "This is the third year in
a row with extreme ice losses, pointing to an acceleration
of the downward trend," he said. "While a 'low'
September ice extent one year is often followed by a recovery
the next year, this was not the case in 2003, which was about
12 percent below average," Serreze said. The September
2004 sea-ice loss was especially evident in extreme northern
Alaska and eastern Siberia. The CU-Boulder researchers used
remote-sensing data from the SSMI satellite to record the
sea-ice changes. "We're seeing more melting of multi-year
ice in the summer," said Julienne Stroeve, a CU-Boulder
scientist with NSIDC involved in the research. "We may
soon reach a threshold beyond which the sea ice can no longer
recover." NSIDC is part of CU-Boulder's Cooperative Institute
for Research in Environmental Sciences.
One possible explanation for the continuing loss of sea ice
is that climate warming from human activities like the burning
of fossil fuels is becoming more apparent, said Serreze. "Climate
models are in general agreement that one of the strongest
signals of greenhouse warming will be a loss of Arctic sea
ice," he said. "Some indicate complete disappearance
of the summer sea ice cover by 2070." Serreze believes
natural climate variability likely plays some part in the
observed changes. "However, the most reasonable view
is that the sea ice decline represents a combination of both
natural variability and the greenhouse effect, with the latter
becoming more evident in coming decades," he said. One
complicating factor is the atmospheric circulation pattern
known as the Arctic Oscillation, which may be contributing
to the loss of the much thicker "multi-year" ice
that has accumulated over many years. "As winds and currents
force this ice southward, more of it melts," said Stroeve.
"And while new ice is still forming in the winters, it
is thinner, and therefore melts faster in the summer than
older ice."
In a study funded by the National Science Foundation conducted
with assistance from CU-Boulder, former graduate student Shari
Fox Gearheard looked at the effects of climate change on Inuit
communities in the Arctic region. "The timing of the
climate and environmental changes observed by Inuit in Nunavut
vary depending on the phenomenon, but in many cases elders
and other experienced Inuit point to the last decade as a
period of considerable change," Gearheard said. Nunavut
is a Canadian Territory established in 1999 that is roughly
the size of Western Europe. Gearheard said one of the most
frequent observations in indigenous communities all across
the circumpolar north is that the weather is more unpredictable
than usual. "In the past, Inuit were able to predict
the weather using traditional indicators such as clouds, winds
and currents," she said. "These indicators are no
longer working."
Inuit elders point out that the sea ice in some places is
thinner, causing dangerous travel conditions, she said. The
ice forms later and breaks up earlier in the year, and the
spring melt season is much shorter than before. In addition,
unexpected storms have left hunting parties stranded, and
harder packed snow due to recent wind changes makes it more
difficult to build igloos for shelter.
The results of Gearheard's work are presented in an interactive
multimedia CD titled "When the Weather is Uggianaqtuq:
Inuit observations of environmental change." Uggianaqtuq
is a North Baffin Inuktitut word meaning to behave unexpectedly
or in an unfamiliar way. Another CU-Boulder project involves
the effects of climate change on North Slope communities in
Alaska, including the effects of loss of ice cover on the
potential for increased damage, erosion and flooding from
severe storms.
CU-Boulder researchers Jim Maslanik of NSIDC said the retreat
of the protective ice edge further offshore later into autumn
has increased the potential for flooding and erosion for coastal
communities such as Barrow. "Another aspect of the changing
ice conditions is that, in addition to the ice edge retreating
far offshore, the rate of retreat of the ice edge has been
very rapid," said Maslanik. "In recent years, this
has resulted in unexpected impacts, such as unusually large
numbers of polar bears being stranded on shore near Barrow."
Supporting information and images, including the CD featuring
Gearheard's work with the Inuit people, is posted on the web
at: http://nsidc.org/news/.
Contact: Mark Serreze, 303-492-2963
Julienne Stroeve, 303-492-3584
Marijke Unger, 303-492-1497
Jim Scott, 303-492-3114
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