Arctic sea ice melts 'even faster'
Pastor Dale Morgan
Arctic sea ice melts 'even faster'*
By Richard Black
Environment correspondent, BBC News website
A widespread Arctic melt would have major impacts on wildlife
Arctic sea ice is melting even faster than last year, despite a cold winter.
Data from the US National Snow and Ice Data Center (NSIDC) shows that
the year began with ice covering a larger area than at the beginning of
2007.
But now it is down to levels seen last June, at the beginning of a
summer that broke records for sea ice loss.
Scientists on the project say that much of the ice is so thin that it
melts easily, and the Arctic may be ice-free in summer within five to 10
years.
I think we're going to beat last year's record, though I'd love to be
wrong-Julienne Stroeve
"We had a bit more ice in the winter, although we were still way below
the long-term average," said Julienne Stroeve from NSIDC in Boulder,
Colorado.
"So we had a partial recovery; but the real issue is that most of the
pack ice has become really thin, and if we have a regular summer now, it
can just melt away," she told BBC News.
In March, Nasa reported that the area covered by sea ice was slightly
larger than in 2007, but much of it consisted of thin floes that had
formed during the previous winter. These are much less robust than
thicker, less saline floes that have already survived for several years.
After a colder winter, ice has been melting even faster than last year
A few years ago, scientists were predicting ice-free Arctic summers by
about 2080. Then computer models started projecting earlier dates,
around 2030 to 2050.
Then came the 2007 summer that saw Arctic sea ice shrink to the smallest
extent ever recorded, down to 4.2 million sq km from 7.8 million sq km
in 1980.
By the end of last year, one research group was forecasting ice-free
summers by 2013.
"I think we're going to beat last year's record melt, though I'd love to
be wrong," said Dr Stroeve.
"If we do, then I don't think 2013 is far off anymore. If what we think
is going to happen does happen, then it'll be within a decade anyway."
Rising tide
Countries surrounding the Arctic are eyeing the economic opportunities
that melting ice might bring.
Canada and Russia are exploring sovereignty claims over tracts of Arctic
seafloor, while just this week US President George Bush has urged more
oil exploration in US waters - which could point the way to exploitation
of reserves off the Alaskan coast.
Summer ice cover in the Arctic has declined sharply
But from a climate point of view, the melt could bring global impacts
accelerating the rate of warming and of sea level rise.
"This is a positive feedback process," commented Dr Ian Willis, from the
Scott Polar Research Institute in Cambridge.
"Sea ice has a higher albedo (reflectivity) than ocean water; so as the
ice melts, the water absorbs more of the Sun's energy and warms up more,
and that in turn warms the atmosphere more - including the atmosphere
over the Greenland ice sheet."
Greenland is already losing ice to the oceans, contributing to the
gradual rise in sea levels. The ice cap holds enough water to lift sea
levels globally by about seven metres (22ft) if it all melted.
Natural climatic cycles such as the Arctic Oscillation play a role in
year-to-year variations in ice cover. But Julienne Stroeve believes the
sea ice is now so thin that there is little chance of the melting trend
turning round.
"If the ice were as thin as it was in the 1970s, last year's conditions
would have brought a dip in cover, but nothing exceptional.
"But now it's so thin that you would have to have an exceptional
sequence of cold winters and cold summers in order for it to rebuild."