Tree rings offer insight into mysterious and devastating radiation storms

New light has been shed on a mysterious, unexpected and devastating astrophysical event, thanks to a study by the University of Queensland (UQ).

A team of researchers, led by Dr Benjamin Pope from the University of Queensland’s School of Mathematics and Physics, applied sophisticated statistics to data from trees thousands of years old, to learn more about radioactive ‘storms’.

“These massive bursts of cosmic radiation, known as the Miyake events, occurred about once every thousand years but their cause is unclear,” Dr. Pope said.

“The leading theory is that they are massive solar flares. We need to know more, because if one of these things happened today, it would destroy technology including satellites, internet cables, long-range power lines and transformers.

“The impact on global infrastructure would not be conceivable.”

Enter the humble tree ring.

First author Chengyuan Zhang, a mathematics student at the University of Queensland, developed a program to analyze every available piece of data about tree rings.

“Since you can calculate tree rings to determine its age, you can also observe historical cosmic events that go back thousands of years,” said Mr. Zhang.

“When radiation hits the atmosphere, it produces radioactive carbon-14, which filters the air, oceans, plants and animals, producing an annual record of radiation in tree rings.

“We designed the global carbon cycle to reconstruct the process over 10,000 years, to gain insight into the scale and nature of Miyake events.”

The popular theory until now was that the Miyake events are giant solar flares.

“But our results challenge this,” said Mr. Zhang. “We’ve shown that they are not associated with sunspot activity, and some of them actually last for a year or two.

“Instead of a single instantaneous explosion or glow, what we might be looking at is some kind of astrophysical ‘storm’ or explosion.”

Dr. Pope said the fact that scientists don’t know exactly what the Miyake events were, or how to predict their occurrence is very disturbing.

“Based on the available data, there is 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 might cause.

“These possibilities are very worrying, and they lay the groundwork for further research.”

The search was published in facts Royal Society A.

Reference: “Modeling of Cosmic Radiation Events in the Tree Ring Radiocarbon Record” by Chengyuan Zhang, Utkarsh Sharma, Jordan A. Dennis, Andrea Scivo, Margot Kotimes, Ulf Buntingen, Matthew J. Owens, Michael W.D and Benjamin J. S. Pope, Proceedings of the Royal Society of Engineering and Mathematical Physics.
DOI: 10.1098 / rspa.2022.0497

The study was also completed with undergraduate students in Mathematics and Physics Utkarsh Sharma and Jordan Denise.

The work was supported by a charitable donation to the University of Queensland from the Big Questions Institute.