FACT BRIEF

Is decreased cosmic ray activity driving global warming?

Friday, August 23, 2024

By Sue Bin Park

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Over 50 years of data has produced no proof that cosmic rays are driving global warming.

While some studies attribute some small contribution to decreased cosmic ray activity, there is a scientific consensus that CO2 is the primary factor driving temperature increases worldwide.

Galactic cosmic rays are high-energy particles released by stars of the Milky Way and other galaxies. These rays hit Earth’s upper atmosphere and produce charged particles called ions.

It is suggested these ions cause an increase in cloud cover, which would shield Earth from radiation and prevent warming; thus, it has been proposed that decreased cosmic ray activity is causing rising temperatures. However, causal links between cosmic rays, clouds, and warming have been debunked by decades of data.

A 2017 paper published in the Journal of Geophysical Research found the effects of cosmic rays on clouds insignificant compared to that of natural emissions like wildfires and volcanoes.

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Sources

Encyclopedia Britannica Cosmic ray

Scientific American Cosmic Rays Not Causing Climate Change

JGR Atmospheres Causes and importance of new particle formation in the present-day and preindustrial atmospheres

JGR Space Physics Can solar variability explain global warming since 1970?

Environmental Research Letters Testing the proposed causal link between cosmic rays and cloud cover

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Skeptical Science is a non-profit science education organization. Our goal is to remove a roadblock to climate action by building public resilience against climate misinformation. We achieve this by publishing debunking of climate myths as well as providing resources for educators, communicators, scientists, and the general public. Skeptical Science was founded and is led by John Cook, a Senior Research Fellow with the Melbourne Centre for Behaviour Change at the University of Melbourne.

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