Testing the proposed causal link between cosmic rays and cloud cover
Open Access
- 1 April 2008
- journal article
- Published by IOP Publishing in Environmental Research Letters
- Vol. 3 (2), 024001
- https://doi.org/10.1088/1748-9326/3/2/024001
Abstract
A decrease in the globally averaged low level cloud cover, deduced from the ISCCP infrared data, as the cosmic ray intensity decreased during the solar cycle 22 was observed by two groups. The groups went on to hypothesize that the decrease in ionization due to cosmic rays causes the decrease in cloud cover, thereby explaining a large part of the currently observed global warming. We have examined this hypothesis to look for evidence to corroborate it. None has been found and so our conclusions are to doubt it. From the absence of corroborative evidence, we estimate that less than 23%, at the 95% confidence level, of the 11 year cycle change in the globally averaged cloud cover observed in solar cycle 22 is due to the change in the rate of ionization from the solar modulation of cosmic rays.Keywords
This publication has 16 references indexed in Scilit:
- Recent oppositely directed trends in solar climate forcings and the global mean surface air temperatureProceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, 2007
- The Sun and the Earth's ClimateLiving Reviews in Solar Physics, 2007
- Empirical evidence for a nonlinear effect of galactic cosmic rays on cloudsProceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, 2006
- Latitudinal dependence of low cloud amount on cosmic ray induced ionizationGeophysical Research Letters, 2004
- A new look at possible connections between solar activity, clouds and climateGeophysical Research Letters, 2002
- Cloud cover variations over the United States: An influence of cosmic rays or solar variability?Geophysical Research Letters, 2001
- Low Cloud Properties Influenced by Cosmic RaysPhysical Review Letters, 2000
- The influence of cosmic rays on terrestrial clouds and global warmingAstronomy and Geophysics, 2000
- Advances in Understanding Clouds from ISCCPBulletin of the American Meteorological Society, 1999
- A doubling of the Sun's coronal magnetic field during the past 100 yearsNature, 1999