Arctic
Sea Ice Set To Hit New Low
By Mark Kinver
14 August, 2007
BBC
Arctic
sea ice is expected to retreat to a record low by the end of this summer,
scientists have predicted.
Measurements made by the
US National Snow and Ice Data Center (NSIDC) showed the extent of sea
ice on 8 August was almost 30% below the long-term average.
Because the region's melting
season runs until the middle of September, scientists believe this summer
will end with the lowest ice cover on record.
Researchers have forecast
ice-free summers in the Arctic by 2040.
NSIDC data showed sea ice
extent for 8 August as 5.8m sq km (2.2m sq miles), compared to the 1979-2000
August average of 7.7m sq km (3.0m sq miles).
The current record low was
recorded in 2005, when Arctic sea ice covered just 5.32m sq km (2.09m
sq miles).
"If you look at data for the first week in August, we are way below
what we saw in 2005," explained Mark Serreze, a senior research
scientist at the NSIDC.
"So unless something
really changes, for example the Arctic suddenly becomes a lot colder,
it is going to be hard not to beat the previous record."
Dr Serreze added that it
was very likely that sea ice cover in the polar region was starting
to respond to human induced climate change, resulting from a greater
concentration of greenhouse gases in the atmosphere.
"We know that natural
climate variability can strongly influence the sea ice, but I think
we are starting to see a positive feedback now.
"In other words, we
cannot explain everything that we have seen just through natural processes.
"Overall, the pattern
will be that you melt a little bit more during the summer and you grow
back a little less during the winter," he told BBC News.
Retreating ice
In December 2006, a study
by US researchers forecast that the Arctic would be ice-free 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
that 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.
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