Here’s the Nature podcast interview with Jasper Kirkby, author of the new study that has denialists all atwitter (again) over cosmic rays.
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.
Voila. The Little Ice Age.
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.
Climate Denial Crock of the Week 