Saturday, September 16
The melting of the sea ice in the Arctic, the clearest sign so far of global warming, has taken a sudden and enormous leap forward, in one of the most ominous developments yet in the onset of climate change.
Two separate studies by Nasa, using different satellite monitoring technologies, both show a great surge in the disappearance of Arctic ice cover in the last two years. One, from the Jet Propulsion Laboratory in California, shows that Arctic perennial sea ice, which normally survives the summer melt season and remains year-round, shrank by 14 per cent in just 12 months between 2004 and 2005.
The overall decrease in the ice cover was 720,000 sq km (280,000 sq miles) - an area almost the size of Turkey, gone in a single year. The other study, from the Goddard Space Flight Centre, in Maryland, shows that the perennial ice melting rate, which has averaged 0.15 per cent a year since satellite observations began in 1979, has suddenly accelerated hugely.
In the past two winters the rate has increased to six per cent a year - that is, it has got more than 30 times faster. The changes are alarming scientists and environmentalists, because they far exceed the rate at which supercomputer models of climate change predict the Arctic ice will melt under the influence of global warming - which is rapid enough.
If climate change is not checked, the Arctic ice will all be gone by 2070, and people will be able to sail to the North Pole. But if these new rates of melting are maintained, the Arctic ice will all be gone decades before that.
The implications are colossal. It will mean extinction in the wild - in the lifetime of children alive today - for one of the world's most majestic creatures, the polar bear, which needs the ice to hunt seals.
It means the possibility of a lethal "feedback" mechanism speeding up global warming, because the dark surface of the open Arctic ocean will absorb the sun's heat, rather than reflect it as the ice cover does now - and so the world will get even hotter.
But most of all, the new developments add to the growing concern that climate change as a process is starting to happen much faster than scientists considered it would, even five years ago when the UN's Intergovernmental Panel on Climate Change published its last report.
"These are the latest in a long series of recent studies, all telling us that climate change is faster and nastier than we thought," said Tom Burke, a former government green adviser and now a visiting professor at Imperial College London.
"An abyss is opening up between the speed at which the climate is changing and the speed at which governments are responding...
..."I think we have a very brief window of opportunity to deal with climate change ... no longer than a decade, at the most," he said.
Michael McCarthy and David Usborne
15 September 2006