Earth's largest-ever solar storm discovered through tree rings 

An international team of researchers has uncovered evidence of the largest solar storm ever identified by studying ancient tree rings. 

The evidence points to a colossal spike in radiocarbon levels from 14,300 years ago, found in tree rings from the French Alps.

Catastrophic solar storm

The colossal storm discovered by the scientists originated from the Sun and was so powerful that a similar event would be catastrophic with modern technology.

Today, a solar storm of this magnitude would cause massive destruction to power grids and satellite systems.

Focus of the study 

The research was conducted by experts at the Collège de France, CEREGE, IMBE, Aix-Marseille University, and the University of Leeds. 

The ancient trees examined for the study were found in the eroded banks of the Drouzet River, near Gap, in the Southern French Alps. 

These trees, categorized as subfossils, showcased individual rings that revealed the unprecedented spike in radiocarbon levels precisely 14,300 years ago.

Creating a timeline

“Finding such a collection of preserved trees was truly exceptional. By comparing the widths of the individual tree rings in the multiple tree trunks, we then carefully pieced together the separate trees to create a longer timeline using a method called dendrochronology,” explained study co-author Professor Cécile Miramont. 

“This allowed us to discover invaluable information on past environmental changes and measure radiocarbon over an uncharted period of solar activity.” 

Gigantic solar storm 

To validate their findings, the team compared the radiocarbon spike with beryllium measurements from Greenland ice cores. 

The experts concluded that the spike was an outcome of a gigantic solar storm, which had the power to hurl massive volumes of energetic particles into the Earth’s atmosphere.

Huge spikes in radiocarbon 

Lead researcher, Professor Edouard Bard, noted that radiocarbon is constantly produced in the upper atmosphere due to cosmic rays.

“Recently, scientists have found that extreme solar events including solar flares and coronal mass ejections can also create short-term bursts of energetic particles which are preserved as huge spikes in radiocarbon production occurring over the course of just a single year,” explained Professor Bard.

Potential damage

Such massive solar occurrences would be disastrous today, as they could disrupt our telecommunications, satellites, and electricity grids, leading to a massive economic cost. 

“Extreme solar storms could have huge impacts on Earth. Such super storms could permanently damage the transformers in our electricity grids, resulting in huge and widespread blackouts lasting months,” said study co-author Tim Heaton.

“They could also result in permanent damage to the satellites that we all rely on for navigation and telecommunication, leaving them unusable. They would also create severe radiation risks to astronauts.”

Extreme solar storms 

Interestingly, this isn’t the first such discovery. Nine extreme solar storms, known as Miyake Events, have been identified from the last 15,000 years. 

However, the 14,300-year-old storm stands out as the most massive, almost double the size of the events from 993 AD and 774 AD. Yet, the nature of these events remains elusive, largely due to the absence of direct instrumental observation.

Understanding the Sun’s behavior 

“Direct instrumental measurements of solar activity only began in the 17th century with the counting of sunspots,” noted Professor Bard.

“Nowadays, we also obtain detailed records using ground-based observatories, space probes, and satellites. However, all these short-term instrumental records are insufficient for a complete understanding of the Sun.”

“Radiocarbon measured in tree-rings, used alongside beryllium in polar ice cores, provide the best way to understand the Sun’s behavior further back into the past.”  

The Carrington Event 

The largest directly observed solar storm was the Carrington Event from 1859. The storm destroyed telegraph machines and created a night-time aurora so bright that birds began to sing.

Although the Carrington Event was massive, it pales in comparison to these ancient Miyake Events. 

Study implications 

Professor Heaton praised the role of radiocarbon in studying Earth’s history, emphasizing the importance of understanding our past to prepare for future risks.

“Radiocarbon provides a phenomenal way of studying Earth’s history and reconstructing critical events that it has experienced,” said Professor Heaton. “A precise understanding of our past is essential if we want to accurately predict our future and mitigate potential risks.” 

“We still have much to learn. Each new discovery not only helps answer existing key questions but can also generate new ones.”  

The study is published in the journal Philosophical Transactions of the Royal Society A Mathematical Physical and Engineering Sciences. 

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