The largest solar storm ever identified in ancient tree rings – it could destroy modern technology and cost billions

Scientists have discovered a radiocarbon spike 14,300 years ago, caused by the largest known solar storm. Such an event today could destroy modern technology and cost billions.

An international team of scientists has discovered a spike in radiocarbon levels 14,300 years ago by analyzing ancient tree rings found in the French Alps.

The radiocarbon spike was caused by a massive solar storm, the largest ever identified.

A similar solar storm today would be catastrophic for modern technological society – potentially wiping out telecommunications and satellite systems, causing widespread power outages, and costing us billions of dollars.

Academics warn that understanding such storms is important to protect the global telecommunications and energy infrastructure in the future.

Tree rings of a fossil tree buried in the Druzet River. Credit: Cécile Miramonte

New research and implications

The collaborative research, conducted by an international team of scientists, will be published today (October 9) in the Journal of the Royal Society. Philosophical Transactions A: Mathematical, physical, and engineering sciences It reveals new insights into the Sun’s extreme behavior and the dangers it poses to Earth.

A team of researchers from the Collège de France, CEREGE, IMBE, the University of Aix-Marseille, and the University of Leeds have measured radiocarbon levels in ancient trees preserved within the eroded banks of the Druzet River, near Gap, in the southern French Alps.

Fossil trees in the Druzet River. Credit: Cécile Miramonte

The logs, which are subfossils—remains in which the fossilization process is not complete—were cut into small, single tree rings. Analysis of these individual episodes identified an unprecedented rise in radiocarbon levels, which occurred precisely 14,300 years ago. By comparing this spike in radiocarbon with measurements of beryllium, a chemical element found in Greenland’s ice cores, the team suggests that the spike was caused by a massive solar storm that would have spewed huge amounts of energetic particles into Earth’s atmosphere.

Expert opinions and historical context

“Radiocarbon is constantly produced in the upper atmosphere through a series of reactions initiated by cosmic rays,” said Edouard Bard, professor of climate and ocean evolution at the College of France and CEREGE, and lead author of the study. “Recently, scientists have found that extreme solar events including Solar flares and coronal mass ejections can also create short-lived bursts of energetic particles that are preserved as huge spikes in radiocarbon production that occur over the course of just one year.

Researchers say that similar massive solar storms today could be catastrophic for modern technological society, potentially destroying communications, satellite systems and electricity networks – and costing us billions of pounds. They warn of the importance of understanding the future risks of such events, to enable us to prepare, build resilience into our communications and energy systems and protect them from potential damage.

Fossil trees on the banks of the Druzet River. Credit: Cécile Miramonte

Tim Heaton, professor of applied statistics at the University of Leeds School of Mathematics, said: “Severe solar storms can have huge impacts on Earth. Such severe storms can permanently damage transformers in our power grids, leading to massive, widespread power outages lasting for months. It could also lead to permanent damage to the satellites we all depend on for navigation and communications, rendering them unusable. It would also create severe radiation risks for astronauts.

Historical solar storms

Nine of these extreme solar storms – known as Miyake events – have now been identified as having occurred over the past 15,000 years. The most recent confirmed Miyake events occurred in 993 AD and 774 AD. However, this newly identified storm, dating back 14,300 years, is the largest ever discovered – roughly twice the size of those two storms.

The exact nature of the Miyake events is still not well understood, as they have never before been effectively observed directly. They highlight that we still have a lot to learn about the Sun’s behavior and the risks it poses to society on Earth. We don’t know what causes such intense solar storms, how frequently they occur, or whether we can somehow predict them.

Professor Bard said: “Direct automated measurements of solar activity only began in the 17th century with sunspot counting. Nowadays, we also obtain detailed records using ground-based observatories, space probes and satellites. However, all these short-term instrumental records are insufficient to fully understand the Sun. Radiocarbon measured in tree rings, used along with beryllium in polar ice cores, provides the best way to understand the Sun’s past behavior.

Radiocarbon and historical reconstruction

The largest directly observed solar storm occurred in 1859 and is known as the Carrington event. It caused massive disruption to the Earth, destroying telegraph machines and creating a nighttime twilight so bright that birds began to sing, thinking the sun was beginning to rise. However, the Miyake events (including the newly discovered 14,300-year-old storm) would have been astonishingly larger in size.

Professor Heaton said: “Radiocarbon provides a wonderful way to study the Earth’s history and reconstruct the crucial events it went through. An accurate understanding of our past is essential if we are to accurately predict our future and mitigate potential risks. We still have a lot to learn. Every new discovery not only helps… Answer key existing questions, but can also generate new ones.

“Finding such a collection of preserved trees was truly exceptional,” said Cécile Miramont, associate professor of paleoenvironments and paleoclimates at IMBE at the University of Aix-en-Provence. “By comparing the width of individual tree rings in multiple tree trunks, we then assembled the trees.” Carefully separated together to create a longer timeline using a method called dendrography, this has allowed us to discover invaluable information about past environmental changes and measure radiocarbon during an unknown period of solar activity.

Reference: “Radiocarbon spikes at 14,300 calories per year in fossil trees provide an impulse response function for the global carbon cycle during the Late Pleistocene” by Bard E, Miramont C, Capano M, Guibal F, Marschal C, Rostek F, Tuna T, Fajault Y and Heaton TJ, October 9, 2023, Philosophical Transactions of the Royal Society A.
doi: 10.1098/rsta.2022.0206