The scientists, at an atmospheric monitoring station in the Norwegian territory of Svalbard, have found that levels of carbon dioxide in the atmosphere near the North Pole are now rising at an unprecedented pace.
In 1990 this key cause of global warming was rising at a rate of 1 part per million (ppm). Recently, that rate reached 2 ppm per year. Now, scientists at the Mount Zeppelin monitoring station have discovered it is rising at between 2.5 and 3 ppm.
'The fact that our data now show acceleration in the rise of carbon dioxide level is really a source for concern,' said Professor Johan Strom, of Stockholm University's department of applied environmental science, which runs the Mount Zeppelin station. 'The increase is also seen at other stations, but our Zeppelin data show the strongest increase.'
The news of the latest carbon dioxide figures comes as scientists prepare to announce details of the forthcoming International Polar Year programme, which will involve teams of scientists from around the world making a concerted attempt to understand the impact of global warming in the world's high latitudes. In particular, they will concentrate on the social impact of climate change there and also the threats to the regions' wildlife, such as polar bears and walruses.
In the last two decades, carbon dioxide levels in the atmosphere have risen from 350 to 380 ppm and scientists warn that once levels reach 500, there could be irreversible consequences that would tip the planet toward disaster: glacier melts triggering devastating sea-level rises and spreading deserts across Africa and Asia.
Scientists and campaigners are desperate for politicians to reach agreements that will prevent the 500 ppm 'tipping point' being breached in the next half-century. These new data suggest they may have a far shorter period of time in which to act.
'Fortunately, this rate of rise of carbon dioxide is not yet seen round the world,' added Strom. 'However, it may be that we have been the first to detect it, and that we are seeing some kind of special effect that could have widespread consequences in a few years.'
One theory proposed by Strom is that heating of the oceans could be leading to the release of carbon dioxide. Other scientists suggest that as the world warms, the Arctic tundra - previously gripped by permafrost - may be giving off carbon dioxide as it melts, releasing gas from vegetation trapped within it that has now started to rot. Thus levels of the gas would increase with particular rapidity near the North Pole.
The latest data from Mount Zeppelin comes in the wake of a series of other alarming reports about the effects of global warming in the Arctic and Antarctic. It was recently discovered that ice sheets are now covering less of the Arctic Ocean than ever before; that Greenland is shedding sheets of ice far faster than previously realised; that the West Antarctic ice cap is dwindling at an unexpectedly high rate; and that the Gulf Stream is showing worrying signs of being disrupted by Arctic meltwaters.
The last effect is particularly worrying, because the waters of the Gulf Stream play a key role in keeping Britain and Europe from freezing in winter. Should it disappear, the consequences for the country would be profound.
'The crucial point is that you can't look at the Arctic and Antarctic in isolation,' said Professor Chris Rapley, head of the British Antarctic Survey. 'What happens there has profound consequences for the rest of the planet.'
It was thought until recently that it would take up to 1,000 years for heat to penetrate the Greenland ice shield and melt it. But the latest data show that large parts of it are actually sliding in lumps into the sea. 'That means it is likely to take far less time to raise sea levels,' added Rapley. 'And if Greenland's ice melts, we will be in trouble. There will be a seven-metre rise in the oceans. The Thames Barrier would be swamped.'
This article is reproduced with permission from The Observer (London) of 12 March, 2006. The report and interactive guides to global warming can be seen on the Guardian Unlimited website.
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