Solar particle events, also known as solar storms, have the power to emit radiation that can be devastating to the Earth’s ozone layer and increase levels of ultraviolet (UV) radiation at the surface. These events occur when the sun emits bursts of energy, mostly protons, which can shoot out into space like a searchlight. Earth’s magnetic field acts as a shield, deflecting electrically charged radiation from the sun and protecting life on the planet.
However, the Earth’s magnetic field is not constant and changes over time. In the past century, the field has weakened by more than 6%, and the north magnetic pole has wandered across northern Canada. Geological records show that there have been periods when the geomagnetic field has been very weak or even entirely absent, similar to Mars, which lost its global magnetic field in the ancient past and most of its atmosphere as a result.
The most recent extreme solar particle event occurred around 993 AD, and evidence of these events can be found in historical records. These events can deplete ozone levels in the upper atmosphere, which absorbs harmful solar UV radiation. A new study using computer models of global atmospheric chemistry found that an extreme solar particle event could deplete ozone levels for a year or more, increasing UV levels at the surface and causing DNA damage.
The combination of a weak magnetic field and extreme solar proton events may explain several mysterious occurrences in Earth’s past. Major evolutionary events, such as the disappearance of Neanderthals in Europe and the extinction of marsupial megafauna in Australia, have been linked to periods of weak magnetic field. The rapid evolution of diverse groups of animals during the Cambrian Explosion has also been related to geomagnetism and high UV levels.
Scientists are still exploring the role of solar activity and Earth’s magnetic field in the history of life on Earth. Research by experts like Prof. Alan Cooper focuses on using ancient DNA to study evolutionary processes associated with climate change, human impacts, and disease. By combining information from various disciplines, such as climate change, archaeology, and microbiology, researchers can better understand how solar activity and geomagnetism have influenced the evolution of life on Earth.
