Cosmic Rays Might Be Responsible For Global Warming

See The Other Climate Theory by Anne Jolis, WSJ, 9-7-11. Excerpts:

"But a few physicists weren't worrying about Al Gore in the 1990s. They were theorizing about another possible factor in climate change: charged subatomic particles from outer space, or "cosmic rays," whose atmospheric levels appear to rise and fall with the weakness or strength of solar winds that deflect them from the earth. These shifts might significantly impact the type and quantity of clouds covering the earth, providing a clue to one of the least-understood but most important questions about climate. Heavenly bodies might be driving long-term weather trends.

The theory has now moved from the corners of climate skepticism to the center of the physical-science universe: the European Organization for Nuclear Research, also known as CERN. At the Franco-Swiss home of the world's most powerful particle accelerator, scientists have been shooting simulated cosmic rays into a cloud chamber to isolate and measure their contribution to cloud formation. CERN's researchers reported last month that in the conditions they've observed so far, these rays appear to be enhancing the formation rates of pre-cloud seeds by up to a factor of 10. Current climate models do not consider any impact of cosmic rays on clouds.

Scientists have been speculating on the relationship among cosmic rays, solar activity and clouds since at least the 1970s. But the notion didn't get a workout until 1995, when Danish physicist Henrik Svensmark came across a 1991 paper by Eigil Friis-Christensen and Knud Lassen, who had charted a close relationship between solar variations and changes in the earth's surface temperature since 1860.

"I had this idea that the real link could be between cloud cover and cosmic rays, and I wanted to try to figure out if it was a good idea or a bad idea," Mr. Svensmark told me from Copenhagen, where he leads sun-climate research at the Danish National Space Institute."

"There's good evidence that pre-industrial climate has frequently varied on 100-year timescales, and what's been found is that often these variations correlate with changes in solar activity, solar wind. You see correlations in the atmosphere between cosmic rays and clouds—that's what Svensmark reported. But these correlations don't prove cause and effect, and it's very difficult to isolate what's due to cosmic rays and what's due to other things.""

"In 2006 we had our first results: We had demonstrated the mechanism" of cosmic rays enhancing cloud formation. The IPCC's 2007 report all but dismissed the theory.

Mr. Kirkby's CERN experiment was finally approved in 2006 and has been under way since 2009. So far, it has not proved Mr. Svensmark wrong. "The result simply leaves open the possibility that cosmic rays could influence the climate," stresses Mr. Kirkby,..."

"But while the cosmic-ray theory has been ridiculed from the start by those who subscribe to the anthropogenic-warming theory, both Mr. Kirkby and Mr. Svensmark hold that human activity is contributing to climate change. All they question is its importance relative to other, natural factors."