During weakenings of the Earth’s geomagnetic shield, extreme solar particle events can threaten the ozone layer and DNA
The new study, published in the PNAS science journal, investigates the impact of extreme SPEs on atmospheric chemistry and surface-level radiation under different geomagnetic field strengths. The results suggest that during a geomagnetic field weakening, an extreme SPE would increase nitrogen oxide concentrations in the polar stratosphere and mesosphere. Further, these changes would lead to reductions in stratospheric ozone, and therefore to elevated harmful UV radiation at the Earth’s surface.
Pavle Arsenović, from the University of Natural Resources and Life Sciences, Vienna, who led this study states: “Our study shows that in the absence of the geomagnetic field, an extreme SPE would elevate ground-level UV radiation which could lead to significant solar-induced damaging impacts on DNA. The results suggest further that extreme SPEs could pose risks to human health and may have influenced evolutionary processes in the past.”
“While geomagnetic field weakenings, known as geomagnetic excursions or reversals, occur sporadically and seldom, they may last several millennia and thus encompass a few extreme SPEs”, tells Professor Ilya Usoskin from the University of Oulu, who was also involved in the study.
The study modelled the impacts of an extreme SPE using atmosphere-ocean-chemistry-climate and solar radiation transfer models. The research article highlights that the alteration of chemical processes in the upper atmosphere can have substantial effects across atmospheric layers all the way down to Earth’s surface. Extreme SPEs and their aftermath are likely to interact with climate change and pose additional challenges to ecosystems and human health.
The ozone layer protects life on Earth
The ozone layer absorbs solar UV radiation 15–35 km above the Earth’s surface. The ozone layer can be depleted by solar particle events. Currently, the Earth’s geomagnetic field deflects these particles, limiting their impact to the polar regions. However, geological records demonstrate periods throughout Earth’s history when the geomagnetic field significantly weakened. During those periods, cosmic ionizing particles can enter Earth’s atmosphere at lower latitudes near the equator and damage the ozone layer globally, resulting in marked increases in surface UV radiation.
The research article was published on 1 July 2024: Arsenovic, P., E. Rozanov, I. Usoskin, ... T. Peter (2024) Global impacts of an extreme solar particle event under different geomagnetic field strengths, Proc. Nat. Acad. Sci., 121, e2321770121, doi: 10.1073/pnas.2321770121.
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