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Given that the Sun powers Earth’s climate system and provides the energy for all life on our planet, it should come as no surprise that changes in solar activity can affect climate conditions. Because total solar irradiance varies only slightly, climate scientists have discounted our variable star as a driver of climate change. At the end of the 20th century, Heinrich Svensmark, of the Danish Space Research Institute, and Eigil Friis-Christensen proposed that solar activity may be a controlling factor for climate by changing low level cloud cover. Not surprisingly this idea was disparaged by mainstream climate science, since it would diminish the importance of greenhouse gases, CO2, the IPCC’s favorite daemon, in particular. Now, after several years of experimentation at CERN, the preliminary results are in and it looks like Svensmark and Friis-Christensen were right after all.

The idea that low solar activity might cause Earth’s climate to cool may not sound far fetched, but the mechanism that is responsible for that cooling may seem counterintuitive—an increase in the number of cosmic rays striking Earth’s atmosphere. For a century, scientists have known that charged particles from space constantly bombard Earth. Originating in distant stars and galaxies, these cosmic rays strike our planet’s atmosphere, where they can ionize volatile compounds. This causes airborne droplets, or aerosols, to condense providing the nuclei around which clouds can form. It is the formation of lowlevel clouds that cools Earth, and that formation is controlled by cosmic rays. Ultimately, the cosmic rays are controlled by the Sun. Here is how we described this revelation in The Resilient Earthchapter 11.

The primary proponent of cosmic ray induced lowlevel cloud formation is Danish physicist Henrik Svensmark, of the Danish Space Research Institute. Svensmark and Eigil Friis-Christensen reported their discovery in a cogent paper in 1997: “Variation of Cosmic Ray Flux and Global Cloud Coverage — a Missing Link in Solar-Climate Relationships.” In it, they describe how ions created in the troposphere by cosmic rays could provide a mechanism for cloud formation. And, since the level of cosmic rays is controlled by the solar cycle, they suggested that the Sun is controlling Earth’s climate variation by changing low-level cloud cover.

Svensmark and Nigel Calder wrote an excellent book The Chilling Stars, describing the theory and the discoveries that led to its formulation. According to Svensmark: “Instead of thinking of clouds as a result of the climate, it’s actually showing that the climate is a result of the clouds, because the clouds take their orders from the stars.” To help prove their hypothesis, an experiment was set up in a basement at the Danish National Space Center, to verify that cosmic rays could cause low level clouds to form under controlled conditions.

The heliosphere deflects cosmic-rays. Svensmark.

The SKY Experiment used a cloud chamber to mimic conditions in the atmosphere. This included varying levels of background ionization and aerosol levels, particularly sulphuric acid (H2SO4). The SKY Experiment demonstrated that more ionization implies more particle nucleation. For more details, including video of Svensmark explaining his theory, see “Chilling Stars Author Henrik Svensmark On Video.”

Still, it took years to convince European scientific funding agencies that this cosmic-ray/cloud formation link was worth investigating. Despite efforts to disprove the Sun/cosmic-ray/cloud link, eventually the CLOUD experiment, Cosmics Leaving Outdoor Droplets, was established. As I reported in 2009, the first experimental results were expected in 2011—and the preliminary results are in.

In an article published online on the Nature website, the first report of experimental results are supportive of a cosmic-ray cloud formation link. The work involved over 60 scientists from 17 countries. In “Cloud formation may be linked to cosmic rays,” the mainstream science journal has grudgingly admitted that Svensmark may, in fact, be correct. “The findings, published today in Nature1, are preliminary, but they are stoking a long-running argument over the role of radiation from distant stars in altering the climate,” the news article states.

The best exhibit of the experiment’s success is shown in the graph below, taken from the report’s supplemental material. As Nigel Calder reported on GWPF, “Tucked away near the end of online supplementary material, and omitted from the printed CLOUD paper in Nature, it clearly shows how cosmic rays promote the formation of clusters of molecules (“particles”) that in the real atmosphere can grow and seed clouds.”

The significance of these results is underscored by the tepid, even hostile reception that the mainstream climate science community is giving them. From the equivocal title of the Nature news announcement to several warmists quoted in the article, their was a definite chill in the air. The CLOUD experiment is “not firming up the connection,” contends Mike Lockwood, a space and environmental physicist at the University of Reading, UK, who is skeptical of the cosmic-ray connection.

In an oddly titled article, “Cloud-making: Another human effect on the climate,” New Scientist, a vocal global warming booster, quotes Jasper Kerkby, a physicist and lead investigator on the project, as saying “[t]his was a big surprise.” When Dr Kirkby first described the theory in 1998, he suggested cosmic rays “will probably be able to account for somewhere between a half and the whole of the increase in the Earth’s temperature that we have seen in the last century.”

The New Scientist article misleadingly spends its first paragraph talking about organic particles and trying to link the CLOUD results to agriculture and other human activities. “If it is significant on a global scale, it might mean that the natural emissions of organics is also important in cloud formation,” said Bart Verheggen of the Energy Research Centre of the Netherlands (see my earlier article on the same topic, “Airborne Bacteria Discredit Climate Modeling Dogma”).

Other responses were more on target, if more guarded. “I think it’s an incredibly worthwhile and overdue experiment,” says Piers Forster, a climatologist at the University of Leeds, UK, who studied the link between cosmic rays and climate for the latest scientific assessment by the International Panel on Climate Change. But for now at least, he says that the experiment “probably raises more questions than it answers.”

Even the more restrained Nature quotes Kirkby as saying, “[a]t the moment, it actually says nothing about a possible cosmic-ray effect on clouds and climate, but it’s a very important first step.” In a more thoughtful moment, Kirkby added, “[p]eople are far too polarized, and in my opinion there are huge, important areas where our understanding is poor at the moment.”

None of this can detract from the experimental findings, however. Quoting from the actual paper’s abstract, “We find that atmospherically relevant ammonia mixing ratios of 100 parts per trillion by volume, or less, increase the nucleation rate of sulphuric acid particles more than 100–1,000-fold.” A 1,000 fold increase in nucleation rate seems well out of the statistical noise as experimental results go.

“Of course there are many things to explore, but I think the cosmic-ray/cloud-seeding hypothesis is converging with reality,” says Henrik Svensmark modestly of the report. For his part, Kirkby hopes to eventually answer the cosmic-ray question. In the coming years, he says, his group is planning experiments with larger particles in the chamber, and they hope eventually to generate artificial clouds for study. “There is a series of measurements that we will have to do that will take at least five years,” he says. “But at the end of it, we want to settle it one way or the other.”

How cosmic-rays help form nuclei promoting could formation. CERN.

Undoubtedly, science will slowly move forward and eventually affirm or reject Svensmark’s theory—that is how science works. For those who refuse to think of science as a struggle, with proponents of competing theories attacking one another, let this be an example. Warm-mongering CO2 demonizers tried to kill this theory in its cradle, claiming that performing experiments like SKY and CLOUD were just a waste of time and money. They would rather stay in their comfort zone, their delusions reinforced by computer models of their own devising, without need for all that tedious experimentation. Fortunately, more inquisitive minds prevailed.

Many scientists think that attacks on climate science dogma are an attack on all science, but that is not true. Such skepticism is what makes science work, and blind belief in current theories is antithetical to the advancement of human understanding. As more and more flaws have been found in the theory of anthropogenic global warming, real scientists have begun to look elsewhere for the real drivers of climate change—to the Sun, the stars and the clouds.

Be safe, enjoy the interglacial and stay skeptical.

The Resilient Earth, 12 September 2011