Tucson Standard

The Northern Lights were visible farther south than usual this year, sparking widespread interest. Researchers have now identified the timing of an ancient solar storm that could have devastating effects on modern technology if it occurred today. The study, led by Irina Panyushkina from the University of Arizona Laboratory for Tree-Ring Research and Timothy Jull from the U of A Department of Geosciences, was published in Communications Earth & Environment.

Analyzing tree rings for carbon-14, a radioactive form of carbon created by cosmic radiation, the team discovered a spike dating to 664 B.C., identifying a significant solar storm event. "After a few months, carbon-14 will have traveled from the stratosphere to the lower atmosphere, where it is taken up by trees and becomes part of the wood as they grow," Panyushkina explained.

Extreme solar storms known as Miyake events were first recognized in 2012 when Japanese physicist Fusa Miyake identified spikes in radioactive carbon isotopes within tree rings. These events occur when increased solar activity allows protons to bombard Earth's atmosphere, causing chemical reactions that lead to isotope spikes.

"Thanks to radiocarbon in tree-rings, we now know that six Miyake events happened over the last 14,500 years," Panyushkina stated. She added that such events would severely impact communication technology if they happened today.

The research involved dissecting ancient wood samples with surgical knives and analyzing them for radiocarbon content. To confirm whether solar storms caused these spikes, researchers compared their data with beryllium-10 isotope levels found in ice cores from glaciers and ice sheets.

"If ice cores from both the North Pole and South Pole show a spike in beryllium-10 corresponding to increased radiocarbon in tree-rings for a particular year, we know there was a solar storm," Panyushkina said.

Despite being able to record these events through tree rings acting like 'archivists,' no discernible pattern has been detected so far. "Tree-rings give us an idea of the magnitude of these massive storms, but we can't detect any type of pattern," Panyushkina noted. She emphasized that their findings could transform how scientists understand extreme solar proton events recorded in tree rings.

"The energy from this type of event not only changes the atmosphere's radiocarbon content but also its chemistry," she added. The research aims to explore how these powerful yet short-lived events affect Earth's systems overall.

Funding for this study came from NASA, the European Union, and Hungary's government.