Researchers have long known that solar activity and cosmic rays have a yin-yang relationship. As solar activity declines, cosmic rays intensify. Lately, solar activity has been very low indeed. Are cosmic rays responding? The answer is “yes.” Spaceweather.com and the students of Earth to Sky Calculus have been using helium balloons to monitor cosmic rays in the stratosphere. Their data show that cosmic rays in the mid-latitude stratosphere now are approximately 12% stronger than they were one year ago:
Cosmic rays, which are accelerated toward Earth by distant supernova explosions and other violent events, are an important form of space weather. They can seed clouds, trigger lightning, and penetrate commercial airplanes. Furthermore, there are studies linking cosmic rays with cardiac arrhythmias and sudden cardiac death in the general population. Among patients who have an implanted cardioverter – defibrillator (ICD), the aggregate number of life-saving shocks appears to be correlated with the number of cosmic rays reaching the ground. References: #1, #2, #3, #4.
Why do cosmic rays increase when solar activity is low? Consider the following: To reach Earth, cosmic rays have to penetrate the inner solar system. Solar storms make this more difficult. CMEs and gusts of solar wind tend to sweep aside cosmic rays, lowering the intensity of radiation around our planet. On the other hand, when solar storms subside, cosmic rays encounter less resistance; reaching Earth is a piece of cake.
Forecasters expect solar activity to drop sharply in the years ahead as the 11-year solar cycle swings toward another deep minimum. Cosmic rays are poised to increase accordingly.