April 3, 2008
Researchers: Sun is Not the Cause of Global Warming
Scientists in the U.K. have reported evidence that further refutes one theory of global climate change.
In the heated debate over global warming, there is an opposing idea, called the cosmic ray theory, which contends that climate change is simply caused by cosmic rays coming from the sun.
However, researchers at Lancaster University reported in the Institute of Physics journal that there has been no correlation between solar activity and the Earth's climate.
Pioneered by Dr. Henrik Svensmark at the Danish National Space Center (DNSC), the cosmic ray theory has led the argument against the popular theory of global warming. It was for this reason that Terry Sloan and his colleagues at Lancaster decided to put Svensmark's theory to the test.
"We started on this game because of Svensmark's work," Sloan said.
"If he is right, then we are going down the wrong path of taking all these expensive measures to cut carbon emissions; if he is right, we could carry on with carbon emissions as normal."
Solar winds are streams of electrically charged particles coming from the Sun that act in diverting cosmic rays away from the earth.
Svensmark's theory says that weak solar winds cause excess cosmic rays to hit the Earth, thus creating more charged particles in the atmosphere and forming more clouds, causing the climate to cool.
When the Sun's output is strong, the planet begins to warm.
The researchers at Lancaster set out to find any historical links between weak cosmic ray arrivals and their effect on cloud coverage in observed locations.
"For example; sometimes the Sun 'burps' - it throws out a huge burst of charged particles," said Sloan.
"So we looked to see whether cloud cover increased after one of these bursts of rays from the Sun; we saw nothing."
One study of the Sun's 11-year cycle saw a weak link between cosmic ray intensity and cloudiness, while the second study showed none.
Dr. Svensmark reacted to Sloan's research.
"Terry Sloan has simply failed to understand how cosmic rays work on clouds," he said.
"He predicts much bigger effects than we would do, as between the equator and the poles, and after solar eruptions; then, because he doesn't see those big effects, he says our story is wrong, when in fact we have plenty of evidence to support it."
In addition to the Lancaster research, Dr. Giles Harrison, of Reading University, also formed a study in the UK, which found a very weak correlation between cosmic rays and cloud formation.
Last year, the Intergovernmental Panel on Climate Change (IPCC) concluded that since temperatures began rising rapidly in the 1970s, the contribution of humankind's greenhouse gas emissions has outweighed that of solar variability by a factor of about 13 to one.
Sloan said that his team failed to verify Svensmark's argument, and that the IPCC is on the right track.
"As far as we can see, he has no reason to challenge the IPCC - the IPCC has got it right," he said.
"So we had better carry on trying to cut carbon emissions."
On the Net:
Institute of Physics Journal
Danish National Space Center
Intergovernmental Panel on Climate Change (IPCC)