Experiment probes connection between climate change and radiation bombarding the atmosphere.
It sounds like a conspiracy theory: ‘cosmic rays’ from deep space might be creating clouds in Earth’s atmosphere and changing the climate. Yet an experiment at CERN, Europe’s high-energy physics laboratory near Geneva, Switzerland, is finding tentative evidence for just that.
The findings, published today in Nature, are preliminary, but they are stoking a long-running argument over the role of radiation from distant stars in altering the climate. …
Early results seem to indicate that cosmic rays do cause a change. The high-energy protons seemed to enhance the production of nanometre-sized particles from the gaseous atmosphere by more than a factor of ten. But, Kirkby adds, those particles are far too small to serve as seeds for clouds. “At the moment, it actually says nothing about a possible cosmic-ray effect on clouds and climate, but it’s a very important first step,” he says.
This has been known for a long time. See:
GCR Cloud Seeding
GCRs must induce aerosol formation
These newly-formed aerosols must grow sufficiently (through the condensation of gases in the atmosphere) to form cloud-condensation nuclei (CCN)
The CCN must lead to increased cloud formation.
The first step is not controversial, and is being investigated by the CERN CLOUD experiment. A recent study by Enghoff et al. (2011) also demonstrated some success in inducing aerosol formation under laboratory conditions, although they have yet to test the process under atmospheric conditions.
However, the second step is often glossed over by those espousing the GCR warming theory. Freshly nucleated particles must grow by approximately a factor of 100,000 in mass before they can effectively scatter solar radiation or be activated into a cloud droplet (Verheggen 2009). Pierce and Adams (2009) investigated this second step by using a a general circulation model with online aerosol microphysics in order to evaluate the growth rate of aerosols from changes in cosmic ray flux, and found that they are far too small to play a significant role in cloud formation or climate change.
“In our simulations, changes in CCN from changes in cosmic rays during a solar cycle are two orders of magnitude too small to account for the observed changes in cloud properties; consequently, we conclude that the hypothesized effect is too small to play a significant role in current climate change.”