Text 27116, 122 rader
Skriven 2007-02-11 18:27:00 av Jeff Binkley (1:226/600)
Ärende: Global warming
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The nerve of these Brits to dare question Owl Gore...


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http://www.telegraph.co.uk/news/main.jhtml?xml=/news/2007/02/11/warm11.x
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Cosmic rays blamed for global warming
By Richard Gray, Science Correspondent, Sunday Telegraph
Last Updated: 1:08am GMT 11/02/2007



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. 

   
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.

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"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."

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