Effects of the Earth's magnetic field – Science News, November 21, 1970
The Earth's magnetic field has been frequently reversed at intervals of 1 to 100 million years. Some scientists now suspect that these investments could have drastic effects on terrestrial life … Over the past 2.5 million years, eight species of single-celled marine animals called Radiolaria have become extinct. Six of these extinctions occurred simultaneously along their geographic range immediately after the magnetic inversions.
The Earth's magnetic field protects the planet from cosmic and solar radiation, but that field can weaken during the reversal of the poles. Such investments may harm more than selected species, perhaps playing a role in some mass extinctions. Direct evidence has eluded researchers, but there are suggestive examples. In 2016, scientists related the mass extinction of marine life 550 million years ago to investments that weakened the magnetic field. The resulting increase in radiation could lead to the disappearance of many shallow-water organisms, the team speculated.