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
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.
"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,
I think we're going to beat last year's record, though I'd love to be wrong
"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
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
Countries surrounding the Arctic are eyeing the economic opportunities that melting ice might bring.
Canada and Russia are exploring soverignity claims over tracts
of Arctic seafloor, while just this week President 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 7m (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