Arctic Sea Ice Shatters Record Low: Diminished Ice Leads To Northwest
Passage Opening*

Arctic sea ice receded so much that the fabled Northwest Passage
completely opened for the first time in human memory.

by Staff Writers
Boulder CO (SPX) Oct 04, 2007

Arctic sea ice during the 2007 melt season plummeted to the lowest
levels since satellite measurements began in 1979, according to
researchers at the University of Colorado at Boulder's National Snow and
Ice Data Center. The average sea ice extent for the month of September
was 1.65 million square miles (4.28 million square kilometers), the
lowest September on record, shattering the previous record for the month
by 23 percent, which was set in 2005. At the end of the melt season,
September 2007 sea ice was 39 percent below the long-term average from
1979 to 2000.

If ship and aircraft records from before the satellite era are taken
into account, sea ice may have fallen by as much as 50 percent from the
1950s. The September rate of sea ice decline since 1979 is now more than
10 percent per decade, said the CU-Boulder research team.

NSIDC is part of the Cooperative Institute for Research in Environmental
Sciences, a joint institute of CU-Boulder and the National Oceanic and
Atmospheric Administration.

Arctic sea ice has long been recognized as a sensitive climate
indicator, said CU-Boulder Research Professor Mark Serreze of CIRES and
NSIDC. "Computer projections have consistently shown that as global
temperatures rise, the sea ice cover will begin to shrink," he said.
"While a number of natural factors have certainly contributed to the
overall decline in sea ice, the effects of greenhouse warming are now
coming through loud and clear."

One factor that contributed to this fall's extreme decline was that the
ice was entering the melt season in an already weakened state, said
CIRES Research Associate Julienne Stroeve of NSIDC. "The spring of 2007
started out with less ice than normal, as well as thinner ice. Thinner
ice takes less energy to melt than thicker ice, so the stage was set for
low levels of sea ice this summer."

Another factor that conspired to accelerate the ice loss this summer was
an unusual atmospheric pattern, with persistent high atmospheric
pressures over the central Arctic Ocean and lower pressures over
Siberia. The scientists noted that skies were fairly clear under the
high-pressure cell, promoting strong melt.

At the same time, the pattern of winds pumped warm air into the region.
While the warm winds fostered further melt, they also helped push ice
away from the Siberian shore. "While the decline of the ice started out
fairly slowly in spring and early summer, it accelerated rapidly in
July," said Walt Meier, a CIRES researcher at NSIDC. "By mid-August, we
had already shattered all previous records for ice extent."

Arctic sea ice receded so much that the fabled Northwest Passage
completely opened for the first time in human memory, said the team.
Explorers and other seafarers had long recognized that this passage,
through the straits of the Canadian Arctic Archipelago, represented a
potential shortcut from the Pacific to the Atlantic.

Roald Amundsen began the first successful navigation of the route
starting in 1903. It took his hardy group two-and-a-half years to
leapfrog through narrow passages of open water, with their ship locked
in the frozen ice through two cold, dark winters. More recently,
icebreakers and ice-strengthened ships have on occasion traversed the
normally ice-choked route.

However, by the end of the 2007 melt season, a standard ocean-going
vessel could have sailed smoothly through. On the other hand, the
Northern Sea Route, a shortcut along the Eurasian coast that is often at
least partially open, was completely blocked by a band of ice this year,
said the researchers.

In addition to the record-breaking retreat of sea ice, the team also
noted that the date of the lowest sea ice extent, or the absolute
minimum, has shifted to later in the year. This year, the five-day
running minimum occurred on Sept 16. From 1979 to 2000, the minimum
usually occurred on Sept. 12.

CIRES Research Associate and NSIDC Senior Scientist Ted Scambos said,
"What we've seen this year fits the profile of lengthening melt seasons,
which is no surprise. As the system warms up, spring melt will tend to
come earlier and autumn freezing will begin later."

Changes in sea ice extent, timing, ice thickness and seasonal
fluctuations are already having an impact on the people, plants, and
animals that live in the Arctic. "Local people who live in the region
are noticing the changes in sea ice," said Arctic resident Shari
Gearheard of CU-Boulder's NSIDC. "The earlier break up and later freeze
up affect when and where people can go hunting, as well as safety for
travel."

The CU-Boulder research team monitors and studies Arctic sea ice year
round, analyzing satellite data and seeking to understand the regional
changes and complex feedbacks, said Serreze. "The sea ice cover is in a
downward spiral and may have passed the point of no return," he said.
"'As the years go by, we are losing more and more ice in summer, and
growing back less and less ice in winter.

"We may well see an ice-free Arctic Ocean in summer within our
lifetimes," said Serreze, noting scientists agree such an event could
occur by 2030. "The implications for global climate, as well as Arctic
animals and people, are disturbing."