Tree Rings Unlock Secrets of Extreme Solar Storms

Understanding tree biology is key to interpreting Earth's history of powerful space weather events.

Jan. 29, 2026 at 6:15am

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Scientists have long used tree rings to study ancient solar storms - bursts of high-energy particles from the sun that can disrupt satellites, power grids, and communication systems. A new study shows that trees don't all record this radioactive carbon in the same way due to differences in how they take up, store, and use carbon. Understanding these biological quirks is crucial for producing more accurate reconstructions of past solar storms and refining estimates of how strong future events could be.

Why it matters

Evidence of powerful solar storms from thousands of years ago, far stronger than anything measured in modern times, is preserved in tree rings around the world. Accurately interpreting this record is important for understanding the potential impacts of extreme space weather on our technology-dependent society today.

The details

The study, co-authored by researchers at Northern Arizona University, reviews how trees absorb, store, and use carbon, and how these processes can affect the timing and strength of the radiocarbon "spikes" left behind by past solar storms, known as Miyake events. Different tree species grow at different times of year, live in different climates, and vary in how they manage stored carbohydrates - all of which can shift how radiocarbon appears in their rings. This knowledge allows scientists to better determine when these historic storms occurred and how intense they were.

  • The study was published in January 2026.

The players

Amy Hessl

A scientist at West Virginia University and the lead author of the paper.

Mariah Carbone

An associate research professor at the Center for Ecosystem Science and Society and Department of Biological Sciences at Northern Arizona University, and the last author on the paper.

Andrew Richardson

A Regents' professor in Ecoss and the School of Informatics, Computing, and Cyber Systems at Northern Arizona University.

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What they’re saying

“Although tree rings are one of our best tools for reading Earth's history, they're not perfect instruments. This paper shows how tree biology shapes the stories they tell.”

— Amy Hessl

“Understanding how trees acquire carbon from the atmosphere, store it for future use and then use it to grow new wood is critical. The biology determines how faithfully the atmospheric signal is preserved.”

— Mariah Carbone, Associate Research Professor

“It's amazing that one way to improve our understanding of solar storms and solar physics is to better understand tree growth processes, which in turn is critical for improving how we use radiocarbon for carbon dating. This study has a lot of implications for applications of carbon dating in fields such as archaeology, for example, as well as the use of radiocarbon in tree rings to reconstruct historical patterns of atmospheric radiocarbon.”

— Andrew Richardson, Regents' Professor

What’s next

The work is part of a larger National Science Foundation project studying just how extreme past solar storms might have been and what similar events could mean for our technology-dependent society today.

The takeaway

Understanding the biological differences in how trees record atmospheric carbon is crucial for accurately interpreting the history of extreme space weather events preserved in tree rings. This knowledge can help refine estimates of the potential impacts of future solar storms on modern infrastructure and technology.