From the Horse’s Mouth. The New Study on Cosmic Rays and Climate.
August 31, 2011
Briefly, the theory is that cosmic rays hit the atmosphere, and when colliding with gas molecules create tiny cloud seeding particles, (“cloud condensation nuclei”) and thus, so the theory goes, could increase cloud cover.
Low clouds, in particular, reflect sunlight, and exert a cooling influence.
Therefore, so the theory goes, when the sun is in an active state, solar magnetic fields are strong, shielding the earth from cosmic rays, not as many clouds form, making it warmer – even warmer than it would be from the more active sun.
In periods such as the Maunder Minimum, a period of very few sunspots from 1645 to 1715, solar activity would have been low, thus, – ->lower magnetic fields –> letting in more cosmic rays —> producing more clouds
—> cooling the planet.
Recently, experiments were undertaken by Dr. Kirkby (interviewed above) at the European Atom smasher facility, – CERN – to learn more about the particle interactions that might validate this theory. The publication of his recent paper on the results has been bouncing around in the denialosphere as yet another “final nail in the coffin of man-caused global warming”.
Dr. Kirkby’s take, as you hear in the interview — not so much.
From the Editor’s summary in Nature:
Even with the large enhancements in rate caused by ammonia and ions, they conclude that atmospheric concentrations of ammonia and sulphuric acid are insufficient to account for observed boundary layer nucleation.
There are more questions to answer.
If cosmic rays have an effect on climate, we should expect that, given the unequivocal warming of the last 40 years, there should be a corresponding trend in cosmic rays. And we don’t see one.
Moreover, solar experts tell us, the sun has been in an extended minimum for several years now.
low solar activity –>
lower solar magnetic fields –>
more influx of cosmic rays –>
more ionizing of atmosphere –>
more cloud nuclei –>
more clouds –>
greater reflectivity –>
lower temps for the last few years, and more cooling to come.
There’s a problem with this idea. We are not observing such a cooling.
For those that need it – here’s more reading.