Arctic ice going, going...
BBC: Arctic ice shrank for fourth consecutive year
It's alarming enough to warrant quoting at length:[US researchers] 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.
"September 2005 will set a new record minimum in the amount of Arctic sea ice cover," said Mark Serreze, of the National Snow and Ice Data Center (NSIDC), Boulder, Colorado.
"It's the least sea ice we've seen in the satellite record, and continues a pattern of extreme low extents of sea ice which we've now seen for the last four years," he told BBC News.
...
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.
The Arctic Climate Impact Assessment, a four-year study involving hundreds of scientists, projected an additional temperature rise of 4-7C by 2100.
If the current trend can be ascribed in part to human-induced climate change, Mark Serreze sees major reasons for concern.
"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.
Possible tipping-points include
Compare the NYT coverage of the story.
It's alarming enough to warrant quoting at length:[US researchers] 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.
"September 2005 will set a new record minimum in the amount of Arctic sea ice cover," said Mark Serreze, of the National Snow and Ice Data Center (NSIDC), Boulder, Colorado.
"It's the least sea ice we've seen in the satellite record, and continues a pattern of extreme low extents of sea ice which we've now seen for the last four years," he told BBC News.
...
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.
The Arctic Climate Impact Assessment, a four-year study involving hundreds of scientists, projected an additional temperature rise of 4-7C by 2100.
If the current trend can be ascribed in part to human-induced climate change, Mark Serreze sees major reasons for concern.
"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.
Possible tipping-points include
- the disappearance of sea ice leading to greater absorption of solar radiation
- a switch from forests being net absorbers of carbon dioxide to net producers
- melting permafrost, releasing trapped methane
Compare the NYT coverage of the story.