For me, the most interesting parts are from 30:00 thru 38:00 when Israeli Nir Shaviv talks about the relationship of cosmic rays, the transit of the solar system through arms of the Milky Way galaxy, and Ice Ages. This is a wonderful theoretical and experimental basis for evaluating Svensmark's cloud thesis.
The bits at 48:00 and 49:30 where the difficulty Svensmark has faced in getting his research published is a burning indictment of the politicization of climate science and the repression carried out by the fanatics who model CO2 and have declared "the science is settled". It isn't settled. The models are flawed. CO2 can't account for past hot house and ice house phases of climate and the models can't post-dict recent and well know climate. They are fatally flawed. But rather than accept this and broaden the search to understand climate, the fanatics have hunkered down and refused to do science. They have turned "global warming" into a belief system, a test of them-versus-us of political correctness. Shame!
Update 2011sep07: Here is a Wall Street Journal article by Anne Jolis on Svensmark's work and the CERN experiment.
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. Those Danes had charted a close relationship between solar variations and changes in the earth's surface temperature since 1860.The last bit is the most critical. The climate warming "skeptics" don't deny that there has been warming (and cooling) of the climate and they don't deny that there isn't an element of human-caused warming. What they debate is the fundamental science, i.e. how much, by what mechanism. The "global warming" crowd starts and ends with models. The skeptics are trying to widen the science to look at all factors.
"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.
He wasn't the first scientist to have the idea, but he was the first to try and demonstrate it. He got in touch with Mr. Friis-Christensen and they used satellite data to show a close correlation among solar activity, cloud cover and cosmic-ray levels since 1979.
They announced their findings and the possible climatic implications in 1996 at a space conference in Birmingham, England. At which point, Mr. Svensmark recalls, "everything went completely crazy. . . . it turned out it was very, very sensitive to say these things already at that time." He returned to Copenhagen to find his local daily leading with a quote from the chair of the U.N. Intergovernmental Panel on Climate Change at the time: "I find the move from this pair scientifically extremely naïve and irresponsible."
Mr. Svensmark had been, at the very least, politically naïve. "Before 1995 I was doing things related to quantum fluctuations. Nobody was interested, it was just me sitting in my office. It was really an eye-opener, that baptism into climate science." He says his work was "very much ignored" by the climate-science establishment—but not by CERN physicist Jasper Kirkby, who is leading today's ongoing cloud-chamber experiment.
And then, he waited. It took six years for CERN to greenlight and fund the experiment. Mr. Kirkby cites financial pressures for the delay and says "it wasn't political."
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, quick to tamp down any interpretation that would make for a good headline.
This seems wise: In July, CERN Director General Rolf-Dieter Heuer told Die Welt that he was asking his researchers to make the forthcoming cloud-chamber results "clear, however, not to interpret them. This would go immediately into the highly political arena of the climate-change debate."
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.