Tree rings provide insight into devastating radiation storms

A University of Queensland study has shed new light on a mysterious, unpredictable, and potentially devastating astrophysical event.

A team led by Dr. Benjamin Pope of UQ’s School of Mathematics and Physics applied state-of-the-art statistics to data from millennia-old trees to learn more about radiation storms.

“These giant bursts of cosmic rays, known as Miyake events, have occurred about once every thousand years, but what causes them is unclear,” said Dr. pope

“The leading theory is that they are giant solar flares. We need to know more, because if any of these happened today, it would destroy technologies like satellites, internet cables, long-distance power lines, and transformers. The impact on global infrastructure would be unimaginable.”

Enter the humble tree ring.

First author Qingyuan Zhang, a mathematics student at UQ, developed software to analyze all available data on tree rings.

“Because you can count a tree’s annual rings to determine its age, you can also observe historical cosmic events going back thousands of years,” Mr. Zhang said. “When radiation hits the atmosphere, it produces radioactive carbon-14, which filters through the air, oceans, plants and animals, producing an annual record of radiation in tree rings. We modeled the global carbon cycle to reconstruct the process over a 10,000 year period to provide insight into the magnitude and nature of the Miyake events.”

The theory held so far has been that Miyake events are giant solar flares.

“But our results call that into question,” Mr. Zhang said. “We have shown that they do not correlate with sunspot activity, and some actually last a year or two. Instead of a single sudden explosion or eruption, we may see some sort of astrophysical ‘storm’ or eruption.”

dr Pope said the fact that scientists don’t know exactly what Miyake events are or how to predict when they will occur is very worrying.

“Based on the available data, there’s about a 1% chance of seeing another one within the next decade. But we don’t know how to predict it or what damage it may cause. These chances are quite alarming and lay the groundwork for further research,” he concluded.

The research is published in Proceedings of the Royal Society Aand was completed with the help of math and physics students Utkarsh Sharma and Jordan Dennis.