Arctic sea ice shrank to the smallest area on record this year, US
scientists have confirmed.*

Ice withdrawal 'shatters record'

Scientists will be looking now to see how well the ice recovers

Arctic sea ice shrank to the smallest area on record this year, US
scientists have confirmed.

[BBC] - 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.

'Fast track'

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.

Modelled decline

In December 2006, a study by US researchers forecast that the Arctic
could be ice-free in summers by 2040.

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 food.

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.