Monday, February 12, 2007

Bulletin: GW Science not quite "settled"

MAN-MADE climate change may be happening at a far slower rate than has been claimed, according to recent research.

Scientists say that cosmic rays from outer space play a far greater role in changing the Earth's climate than global warming experts previously thought.

In a book to be published this week, they say that fluctuations in the number of cosmic rays hitting the atmosphere directly alter the amount of cloud covering the planet.

High levels of cloud cover blanket the Earth and reflect heat from the sun back out into space, causing the planet to cool.

Henrik Svensmark, a weather scientist at the Danish National Space Centre who led the team behind the research, believes that the planet is experiencing a natural period of low cloud cover due to fewer cosmic rays entering the atmosphere.

This, he says, is responsible for much of the global warming we are experiencing.

Carbon dioxide emissions due to human activity are having a smaller impact on climate change than scientists think, he says. If he is correct, it could mean that mankind has more time to reduce its effect on the climate.

Dr Svensmark said: "It was long thought that clouds were caused by climate change, but now we see that climate change is driven by clouds. This has not been taken into account in the models used to work out the effect carbon dioxide has had."

The controversial theory comes after 2500 scientists who make up the United Nations International Panel on Climate Change published their fourth report saying that human carbon dioxide emissions would cause temperature rises of up to 4.5 degrees by the end of the century.

A team of more than 60 scientists from around the world is preparing to conduct a large-scale experiment using a particle accelerator in Geneva, Switzerland, to replicate the effect of cosmic rays hitting the atmosphere.

They hope this will prove whether this deep space radiation is responsible for changing cloud cover.

But some climate change experts have dismissed the claims as tenuous.

Giles Harrison, a cloud specialist at Reading University, said that he had carried out research on cosmic rays and their effect on clouds, but believed the impact on climate was much smaller than Dr Svensmark claimed.

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