[6] In 1997, Svensmark and Eigil Friis-Christensen popularised a theory that linked galactic cosmic rays and global climate change mediated primarily by variations in the intensity of the solar wind, which they have termed cosmoclimatology.

[7] One of the small-scale processes related to this link was studied in a laboratory experiment performed at the Danish National Space Center (paper published in the Proceedings of the Royal Society A, February 8, 2007).

In April 2012, Svensmark published an expansion of his theory in the Monthly Notices of the Royal Astronomical Society[16] In the new work he claims that the diversity of life on Earth over the last 500 million years might be explained by tectonics affecting the sea-level together with variations in the local supernova rate, and virtually nothing else.

The director of DTU Space, Prof. Eigil Friis-Christensen, commented: "When this enquiry into effects of cosmic rays from supernova remnants began 16 years ago, we never imagined that it would lead us so deep into time, or into so many aspects of the Earth's history.

[17] To investigate the role of cosmic rays in cloud formation low in the Earth's atmosphere, the SKY experiment used natural muons (heavy electrons) that can penetrate even to the basement of the National Space Institute in Copenhagen.

Further experiments by Svensmark and collaborators published in 2013[18] showed that aerosols with diameter larger than 50 nm are produced by ultraviolet light (from trace amounts of ozone, sulfur dioxide, and water vapor), large enough to serve as cloud condensation nuclei.

CERN's multinational project will give scientists a permanent facility where they can study the effects of both cosmic rays and charged particles in the Earth's atmosphere.

[28] Dr. Giles Harrison of Reading University, describes the work as important "as it provides an upper limit on the cosmic ray-cloud effect in global satellite cloud data".

Brian H. Brown (2008) of Sheffield University further found a statistically significant (p<0.05) short term 3% association between Galactic Cosmic Rays (GCR) and low level clouds over 22 years with a 15-hour delay.

[30] More recently, Laken et al. (2012)[31] found that new high quality satellite data show that the El Niño Southern Oscillation is responsible for most changes in cloud cover at the global and regional levels.

Sloan and Wolfendale (2013)[33] demonstrated that while temperature models showed a small correlation every 22 years, less than 14 percent of global warming since the 1950s could be attributed to cosmic ray rate.

"[34] In 2013, a laboratory study by Svensmark, Pepke and Pedersen published in Physics Letters A showed that there is in fact a correlation between cosmic rays and the formation of aerosols of the type that seed clouds.