## Sunday, September 17, 2006 ... //

### Cosmic rays will create clouds at CERN

A new central article about the cosmic/solar climate connection on this blog has been created
Paul Krapivsky (B.U.) has pointed out a rather interesting new article in Nature, volume 443.

You must be a subscriber to be allowed to click the link above. Jeff Kanipe describes an experiment that will be performed at CERN in Switzerland and that will fully start in 2010. The experiment will study the formation of clouds in a C.T.R. Wilson's cloud chamber as a function of the intensity of (artificial) cosmic rays sent from the synchrotron into the cloud chamber at different levels of humidity.
Warning: This story is not about the Large Hadron Collider (click), another (and much larger) experiment at CERN!
What is the purpose of this toy? There seems to be a disagreement between many astrophysicists, nuclear physicists and related scientists on one side and most climate scientists on the other side. The astrophysicists tend to believe that the Solar and galactic cosmic rays are important to determine the cloud formation and therefore the climate on the Earth. The climate scientists usually believe that the main driver of the climate is something completely different.

CLOUD (Cosmics Leaving Outdoor Droplets) have a chance to resolve this question.

Many arguments have appeared in literature that indicate that the cosmic rays matter. Svensmark and Friis-Christensen of Denmark have argued in 1997 that the cloudiness between 1987 and 1990 declined by 3 percent or so, just like the number of cosmic rays reaching the Earth; the original driver of the cosmic rays intensity were the fluctuating sunspots. This argument has been extended to longer periods of time.

Also, Nir Shaviv, who has a blog, and Ján Veizer - a Slovak-Canadian emeritus professor - have argued that the ice ages in the last millions of years may have been correlated with the motion of the Solar system through the galactic arms which caused variations in the cosmic ray flux. The general mechanism is always the same: higher amount of cosmic rays is supposed to create a higher amount of clouds which should cool the Earth. The previous blog text about solar forcing is here.

The criticism of Rahmstorf et al. seems somewhat weak to me. After less than one page of negative words whose essence or justification I don't quite understand, they present graphs showing the correlation of CO2 and temperatures. No one has any doubts about it.

We have already explained why we know that the temperature is the primary driver and the gas concentrations are its consequences in this correlation. But this correlation still doesn't explain why the temperatures (or gas concentrations) evolved exactly the way they did. Shaviv and Veizer have a possible galactic model, Rahmstorf et al. - just like Royer et al. (27 cits) - have no model.

Peter Foukal might know what he is doing. But realclimate.org "could quibble with [Foukal's] use of paleo-reconstructions, their climate modeling approach, and the rather cursory treatment of the substantial body of work relating to amplyfying mechanisms due to UV/ozone links" but they liked the conclusions, so the paper got an "A" from them in an article named much like a recent not-quite-serious book about physics.

Scafetta and West (Geophysical Research Letters) find a significant correlation between the pre-industrial temperatures and the total solar irradiation - unexplainable by existing climate models - and estimate the contribution of the Sun to the 20th century warming as 50%.

Back to the big picture and CLOUD

In this disagreement of two communities, the astrophysicists are arguably smarter than the climate scientists and they are less politicized. But science has a slightly different criterion to decide who is right: an experiment.

This experiment costs 9 million euro and 55+ physicists and atmospheric scientists who work on it find it very conceivable that the cosmic rays are crucial for the whole climate - in sharp contradiction with the myth about a "consensus otherwise" in various newspapers and left-wing blogs. Within climate science, I think that such experiments are among the best things to try because they look at the real possible microscopical mechanisms that could matter. Real science can sometimes cost real money. ;-)

Good luck to CLOUD.

Incidentally, the sticker "heliophysics" two lines lower will lead you to 10+ articles; many of them are related to the role of the Sun for the climate.