Findings from a just published study

A new study just published in the Aug. 19th issue of Journal of Geophysical Research: Space Physics comes down in favor of cosmic rays. According to spaceweather.com, a team of scientists from the Technical University of Denmark (DTU) and the Hebrew University of Jerusalem has linked sudden decreases in cosmic rays to changes in Earth’s cloud cover. These rapid decreases in the observed galactic cosmic ray intensity are known as “Forbush Decreases” and tend to take place following coronal mass ejections (CMEs) in periods of high solar activity. When the sun is active (i.e., solar storms, CMEs), the magnetic field of the plasma solar wind sweeps some of the galactic cosmic rays away from Earth. In periods of low solar activity, more cosmic rays bombard the earth. The term “Forbush Decrease” was named after the American physicist Scott E. Forbush, who studied cosmic rays in the 1930s and 1940s.

The research team led by Jacob Svensmark of DTU identified the strongest 26 “Forbush Decreases” between 1987 and 2007, and looked at ground-based and satellite records of cloud cover to see what happened. In a recent press release, their conclusions were summarized as follows: “[Strong “Forbush Decreases”] cause a reduction in cloud fraction of about 2 percent corresponding to roughly a billion tonnes of liquid water disappearing from the atmosphere.”

Current cosmic ray activity

We happen to be in a weak solar cycle (24) which is actually on pace to be the weakest cycle in more than one hundred years. Therefore, it would not be surprising to have relatively high cosmic ray penetration into the Earth’s atmosphere; especially, since we are now heading towards the next solar minimum phase when solar activity is generally even quieter.

In fact, for the past year, neutron monitors around the Arctic Circle have sensed an increasing intensity of cosmic rays. Polar latitudes are a good place to make such measurements, because Earth’s magnetic field funnels and concentrates cosmic radiation there. As it turns out, Earth’s poles aren’t the only place cosmic rays are intensifying. “Spaceweather.com” has led an effort in the launching of helium balloons to the stratosphere to measure radiation, and they find the same trend increasing intensity of cosmic rays over California [For more on this study click here]: