Arctic Sea Ice Hitting Record Low
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Aug. 2007 - Arctic sea ice fell below all
previous records for the lowest absolute minimum extent ever measured by
satellite on Thursday and Friday, said scientists at the National Snow and
Ice Data Center. Sea ice extent has fallen below the 2005 record low
absolute minimum and is still melting, said researcher Walt Meier.
A rapid disintegration of Arctic sea ice during July has prompted
scientists to warn there is a 92 percent chance that Arctic sea ice extent
will hit an annual record low. Sea ice extent, the area of an ocean
covered by at least 15 percent of ice, has been shrinking since the late
1970s, when satellite measurements began.
The decline is believed by many researchers to be due to higher
temperatures due to global warming from a buildup of greenhouse gas
emissions in the Earth's atmosphere.
In April, scientists at the University of Colorado-Boulder forecast a 33
percent chance that the September minimum of sea ice would set a new
annual low record, but after observing what happened to the ice in July,
they drastically revised that prediction.
"During the first week in July, the Arctic sea ice started to disappear at
rates we had never seen before," said Sheldon Drobot, who leads the Arctic
Regional Ice Forecasting System group at the Colorado Center for
Astrodynamics Research, CCAR.
The group at the University of Colorado-Boulder's aerospace engineering
sciences department is the only group in the world making seasonal Arctic
sea ice forecasts based on probability.
Arctic sea ice researchers pay particular attention to the months of
September and March because they generally mark the annual minimum and
maximum sea ice extents respectively, said Drobot.
The record low September minimum for sea ice, set in 2005, is 2.15 million
square miles, Drobot said.
For 2007, the most likely minimum extent is 1.96 million square miles, he
said.
But there is a 25 percent chance the September sea ice extent will shrink
even more - to 1.88 million square miles - said Drobot, and even a five
percent chance it will fall to 1.75 million square miles, he said.
Arctic sea ice is "one of the better predictors of climate change on
Earth," Drobot said. "There will probably be about two-thirds as much sea
this September as there was 25 years ago, a good indication that something
significant is happening with the climate."
The factors triggering the unusually strong July sea-ice decline appear to
be a combination of less multi-year ice and more cloud-free days, which
accelerated the melting effects of solar radiation on the ice, Drobot
said. "Things can really change fast, which is why we continually update
our forecasts," he said.
The sea ice research by the CCAR group is funded by the National Science
Foundation and NASA.
"We have been seeing a sharp decline in thicker, multi-year ice that has
survived more than one melt season," said CCAR scientist James Maslanik.
"This has been replaced in many areas by a thin, first-year layer of ice
as well as by younger, thinner types of multi-year ice. The thinner ice
just does not have the mass to withstand the effects of warming climate,"
Maslanik explained.
The CCAR researchers used satellite data from the U.S. Department of
Defense and temperature records from the National Oceanic and Atmospheric
Administration for the forecasts, which they have been producing for five
years.
Melting sea ice, Blackhead, Newfoundland, Canada. June 2007
Currently, sea ice extent is particularly low in the East Siberian side of
the Arctic and the Beaufort Sea north of Alaska. Ice in the Canadian
Archipelago is also quite low, the scientists said. Along the Atlantic
side of the Arctic Ocean, sea ice extent is not as strikingly low, but is
still less than normal.
Over the past few years, the Arctic sea ice decline has been sharpest in
the western Arctic, said Drobot. Such regional variation is of interest to
the maritime industry, including government agencies, international
shipping companies, energy exploration corporations and tourism cruise
lines active in the far North, he said.
"This type of information is useful for ship operators trying to plan
activities several months out," Drobot said. "It's also useful for
short-term operational planning, including cruise ship excursions."
Assuming the sea ice decline continues in the Arctic, there probably will
be intercontinental "Northwest Passage" type of transit from North America
to places like Europe in the coming decades, Drobot projected.
A seasonal or year-round, ice-free channel through Arctic waters would be
shorter and cost less than shipping through the Panama Canal.
Find more information on CU-Boulder's Arctic Regional Ice Forecasting
System group at: http://ccar.colorado.edu/arifs.
View a website with continuous updates on Arctic sea ice conditions
maintained by researchers at CU-Boulder's National Snow and Ice Data
Center.
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