IN CASE YOU MISSED IT...Cosmic rays blamed for global warming
February 11, 2007
The Sunday Telegraph
Cosmic rays blamed for global warming
By Richard Gray, Science Correspondent, Sunday Telegraph
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Man-made climate change may be happening at a far slower rate than has been claimed, according to controversial new 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 claim that fluctuations in the number of cosmic rays hitting the atmosphere directly alter the amount of cloud covering the planet.
How cosmic rays could seed clouds diagram
High levels of cloud cover blankets the Earth and reflects radiated 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.
He claims carbon dioxide emissions due to human activity are having a smaller impact on climate change than scientists think. If he is correct, it could mean that mankind has more time to reduce our effect on the climate.
The controversial theory comes one week after 2,500 scientists who make up the United Nations International Panel on Climate Change published their fourth report stating that human carbon dioxide emissions would cause temperature rises of up to 4.5 C by the end of the century.
Mr Svensmark claims that the calculations used to make this prediction largely overlooked the effect of cosmic rays on cloud cover and the temperature rise due to human activity may be much smaller.
He 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.
"We may see CO2 is responsible for much less warming than we thought and if this is the case the predictions of warming due to human activity will need to be adjusted."
Mr Svensmark last week published the first experimental evidence from five years' research on the influence that cosmic rays have on cloud production in the Proceedings of the Royal Society Journal A: Mathematical, Physical and Engineering Sciences. This week he will also publish a fuller account of his work in a book entitled The Chilling Stars: A New Theory of Climate Change.
A team of more than 60 scientists from around the world are 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. If so, it could force climate scientists to re-evaluate their ideas about how global warming occurs.
Mr Svensmark's results show that the rays produce electrically charged particles when they hit the atmosphere. He said: "These particles attract water molecules from the air and cause them to clump together until they condense into clouds."
Mr Svensmark claims that the number of cosmic rays hitting the Earth changes with the magnetic activity around the Sun. During high periods of activity, fewer cosmic rays hit the Earth and so there are less clouds formed, resulting in warming.
Low activity causes more clouds and cools the Earth.
He said: "Evidence from ice cores show this happening long into the past. We have the highest solar activity we have had in at least 1,000 years.
"Humans are having an effect on climate change, but by not including the cosmic ray effect in models it means the results are inaccurate.The size of man's impact may be much smaller and so the man-made change is happening slower than predicted."
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 is much smaller than Mr Svensmark claims.
Mr Harrison said: "I have been looking at cloud data going back 50 years over the UK and found there was a small relationship with cosmic rays. It looks like it creates some additional variability in a natural climate system but this is small."
But there is a growing number of scientists who believe that the effect may be genuine.
Among them is Prof Bob Bingham, a clouds expert from the Central Laboratory of the Research Councils in Rutherford.
He said: "It is a relatively new idea, but there is some evidence there for this effect on clouds."