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Climate change and cosmic rays

Danish National Space Center

I usually write about articles that appear on the web but I am going to vary from that in this instance to talk about a site. The Danish National Space Center, which appears to have some relationship with the Technical University of Denmark, has several pages dedicated to the theories of cosmic rays and their influence on clouds on planet Earth. I tend to be a little skeptical about this line of reasoning but have now read enough about it to think that there may be some level of influence in this area.

I suggest that you take a look at the site and poke around. I am sure that you will learn things, especially if you have an open mind.  My long time readers know that I have been on the soapbox for some time on better climate models so I will start the following quotes with that statement:

How can cosmic rays influence cloud formation?

Cosmic rays ionize the atmosphere and an experiment performed at the Danish National Space Center has found that the production of aerosols in a sample atmosphere with condensable gases (such as sulphuric acid and water vapor) depends on the amount of ionization. Since aerosols work as precursors for formation of cloud droplets, this is an indication that cosmic rays affect climate.

Climate models only include the effects of the small variations in the direct solar radiation (infrared, visible and UV). The effects of cosmic rays on clouds are not included in models and the models do a rather poor job of simulating clouds in the present climate. Since cloud feedbacks are a large source of uncertainty, this is a reason for concern when viewing climate model predictions.
The Danish National Space Center, DNSC, comprises the country’s largest collected expertise in the scientific disciplines that play a major and documented role in the understanding of climate change both in geological and historical time, namely variations in solar activity. DNSC regards it essential that this collected expertise is being used in an attempt to understand the natural causes of climate change in order to evaluate the contribution of natural causes to global change. Taking into account the large uncertainty associated with the estimated human contribution, a good research based estimate of the range of natural climate variations is an essential information.
The scientific results have been published internationally and indicate that the varying activity of the Sun is indeed the largest and most systematic contributor to natural climate variations. The effect goes through solar modulation of the cosmic radiation, which affects the formation of aerosols and thereby also the formation of clouds. Even though a physical mechanism connecting cosmic rays to aerosol formation has been found experimentally, no climate model has yet made an attempt to include such an effect.

For more than 20 years, satellite records of low-altitude clouds have closely followed variations in cosmic rays. Just how cosmic rays take part in cloud-making appeared in the SKY experiment, conducted in the basement of the Danish National Space Center. Electrons set free in the air by passing cosmic rays help to assemble the building blocks for cloud condensation nuclei on which water vapour condenses to make clouds.
Cosmic ray intensities and therefore cloudiness keep changing because the Suns magnetic field varies in its ability to repel cosmic rays coming from the Galaxy, before they can reach the Earth. Radioactive carbon-14 and other unusual atoms made in the atmosphere by cosmic rays provide a record of how cosmic-ray intensities have varied in the past.  They explain repeated alternations between cold and warm periods during the past 12,000 years. Whenever the Sun was feeble and cosmic-ray intensities were high, cold conditions ensued, most recently in the Little Ace Age that climaxed 300 years ago.

The above quotes were taken from several pages on the DNSC site.  I suggest that you follow the link here and then poke around the various articles.

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