Withdrawal 'Shatters Record'
22 September, 2007
Arctic sea ice shrank to
the smallest area on record this year, US scientists have confirmed.
The National Snow and Ice Data Center (NSIDC) said the minimum extent
of 4.13 million sq km (1.59 million sq miles) was reached on 16 September.
The figure shatters all previous
satellite surveys, including the previous record low of 5.32 million
sq km measured in 2005.
Earlier this month, it was
reported that the Northwest Passage was open.
The fabled Arctic shipping
route from the Atlantic to the Pacific is normally ice-bound at some
location throughout the year; but this year, ships have been able to
complete an unimpeded navigation.
Arctic sea ice loses area
in summer months and regrows in the winter cold.
The researchers at NSIDC
judge the ice extent on a five-day mean. The minimum for 2007 falls
below the minimum set on 20-21 September 2005 by an area roughly the
size of Texas and California combined, or nearly five UKs.
Speaking to BBC News on Monday
this week, Mark Serreze, a senior research scientist at the NSIDC, said:
"2005 was the previous record and what happened then had really
astounded us; we had never seen anything like that, having so little
sea ice at the end of summer. Then along comes 2007 and it has completely
shattered that old record."
He added: "We're on
a strong spiral of decline; some would say a death spiral. I wouldn't
go that far but we're certainly on a fast track. We know there is natural
variability but the magnitude of change is too great to be caused by
natural variability alone."
The team will now follow
the progress of recovery over the winter months.
In December 2006, a study
by US researchers forecast that the Arctic could be ice-free in summers
A team of scientists from
the National Center for Atmospheric Research (NCAR), the University
of Washington, and McGill University, found that "positive feedbacks"
were likely to accelerate the decline of the region's ice system.
Sea ice has a bright surface which reflects 80% of the sunlight that
strikes it back into space. However, as the ice melts during the summer,
more of the dark ocean surface becomes exposed.
Rather than reflecting sunlight,
the ocean absorbs 90% of it, causing the waters to warm and increase
the rate of melting.
Scientists fear that this
feedback mechanism will have major consequences for wildlife in the
region, not least polar bears, which traverse ice floes in search of
On a global scale, the Earth
would lose a major reflective surface and so absorb more solar energy,
potentially accelerating climatic change across the world.
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