Cosmic Rays spur the formation of clouds. It's a CERNtancy!

CERN is the European Organization for Nuclear Research. They virtually invented the internet. The first ever web site address was Info.cern.ch.

That changed the world.

Cartoons by Josh

Now, the 8,000 scientists from CERN (or at least 60 of them) have made an important contribution to climate physics, prompting climate models to be revised.

As Andrew Orlowski writes in The Register:

The first results from the lab's CLOUD ("Cosmics Leaving OUtdoor Droplets") experiment published in Nature today confirm that cosmic rays spur the formation of clouds through ion-induced nucleation. Current thinking posits that half of the Earth's clouds are formed through nucleation. The paper is entitled Role of sulphuric acid, ammonia and galactic cosmic rays in atmospheric aerosol nucleation.
This has significant implications for climate science because water vapour and clouds play a large role in determining global temperatures. Tiny changes in overall cloud cover can result in relatively large temperature changes.

As Andrew mentions, the results were posted in Nature HERE.

Nature 476, 429–433 (25 August 2011) doi:10.1038/nature10343

Received 09 September 2010: Accepted 24 June 2011 Published online 24 August 2011

Veteran science editor Nigel Calder, who brought the theory to wide public attention with the book The Chilling Stars, co-authored with the father of the theory Henrik Svensmark, has an explanation and background on his blog, here, and offers possible reasons on why the research, mooted in the late 1990s, has taken so long.
Svensmark, who is no longer involved with the CERN experiment, says he believes the solar-cosmic ray factor is just one of four factors in climate. The other three are: volcanoes, a "regime shift" that took place in 1977, and residual anthropogenic components.
When (CLOUD's lead physicist) Dr (Jasper) 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."
More from CERN here, and a video here.®

That short video is great. For another See post: Svensmark: The Cloud Mystery.