EcoAlert: CERN Says Cosmic Rays from Supernovas May Trigger Cloud Formation

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Scientists working on this issue at the European Organization for Nuclear Research (Cern) in Geneva have presented initial results suggesting cosmic rays have an effect on cloud formation but found no proof they drive climate change.

The preliminary findings of the Cosmics Leaving Outdoor Droplets (CLOUD) experiment,  published in Nature journal on Wednesday, show that a few kilometres up in the atmosphere cosmic rays cause a ten-fold increase in the formation rate of tiny aerosol particles.
 


The international team of scientists from 18 institutes found that while cosmic rays “significantly enhanced” the formation of aerosol particles in the mid-troposphere and above, which could grow into the seeds for clouds, in the lower atmosphere additional vapours such as ammonia are required.

 The research also revealed that the chemicals believed to seed clouds -  sulphuric acid, water and ammonia – even with cosmic ray enhancement are not sufficient to explain atmospheric observations of aerosol formation. Additional vapors of organic or human origin may play a far more important role in cloud formation than suspected.
 
Clouds are important for regulating global temperatures as they reflect part of the sun’s heat back into space. But the formation of aerosols that seed clouds is not well understood and is a source of uncertainty in climate models.

There has been a long-running controversy over the possible role of cosmic rays in the creation of aerosols. In the 1990s Danish researchers first suggested that cosmic rays generated supernovas help generate low-altitude clouds.
 
The number of cosmic rays that hit the Earth is lower when the Sun’s activity is high. It has also been suggested that reduced cosmic rays may lead to reduced cloud formation, causing global temperatures to rise. Some climate change sceptics say this process, rather than the burning of fossil fuels, can explain much of the Earth’s recent rise in temperature.

At Cern a custom-built ultra-clean stainless steel chamber filled with highly purified air, water vapour, sulphur dioxide, ozone and ammonia was used to recreate the Earth’s atmosphere. The researchers bombarded the chamber with a beam of proton particles from the Cern's Proton Synchrotron accelerator to provide a source of artificial cosmic rays.
 
By controlling the chamber’s temperature and pressure, they reproduced conditions found at different altitudes and latitudes, and were able to sample the artificial atmosphere to see what effect the rays were having.
 
"Of course there are many things to explore, but I think the cosmic-ray/cloud-seeding hypothesis is converging with reality," Henrik Svensmark, a physicist at the Technical University of Denmark in Copenhagen, who claims a link between climate change and cosmic rays, told Nature.
 
Mike Lockwood, a space and environmental physicist at the University of Reading in England, said small particles may not grow fast enough or large enough to be important in comparison with other cloud-forming processes in the atmosphere.
 
Piers Forster, a climatologist at the University of Leeds, who studied the link between cosmic rays and climate for the latest scientific assessment by the International Panel on Climate Change, said it would be wrong to conclude that cosmic rays were a major driver of climate change.
                                  
The study confirms that cosmic rays can help produce aerosol particles, but also shows they do not contribute much in the lower atmosphere.
                                 
The group plan to continue their experiments over the next five to ten years with more, complex components and larger particles in the chamber, and they hope eventually to generate artificial clouds for study.

The Daily Galaxy via nature.com

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