Arctic ice 'disappearing fast'

By Richard Black Environment Correspondent, BBC News website

The area covered by sea ice in the Arctic has shrunk for a fourth consecutive year, according to new data released by US scientists.

They say that this month sees the lowest extent of ice cover for more than a century. The Arctic climate varies naturally, but the researchers conclude that human-induced global warming is at least partially responsible.

They warn the shrinkage could lead to even faster melting in coming years.
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The current rate of shrinkage they calculate at 8% per decade; at this rate there may be no ice at all during the summer of 2060.
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Though there are significant variations across the region, on average the Arctic is warming twice as fast as the rest of the planet, according to a major report released last year.

"What we're seeing is a process in which we start to lose ice cover during the summer," he said, "so areas which formerly had ice are now open water, which is dark. "These dark areas absorb a lot of the Sun's energy, much more than the ice; and what happens then is that the oceans start to warm up, and it becomes very difficult for ice to form during the following autumn and winter.

"It looks like this is exactly what we're seeing - a positive feedback effect, a 'tipping-point'." The idea behind tipping-points is that at some stage the rate of global warming would accelerate, as rising temperatures break down natural restraints or trigger environmental changes which release further amounts of greenhouse gases.

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