Ancient tree showed remnants of the largest-ever solar storm: researchers

An ancient pine tree in the French Alps led researchers to discover the largest-ever solar storm in Earth's history.

Evidence suggests there was a "huge" spike in radiocarbon levels about 14,300 years ago, which scientists believe was caused by this newly identified solar storm.

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And is Estimated as being twice the size of two previously discovered solar storms that occurred in 993 AD and 774 AD — known as the Miyake Events - the storm is the largest of any that have been uncovered so far.

The research, published on Monday in the journal of Royal Society's Philosophical Transactions, shows how strong the Sun's storms can be.

A group of international researchers from Collège de France, CEREGE, IMBE, Aix-Marseille University and the University of Leeds said they measured radiocarbon levels in ancient trees in the southern French Alps.

They said the rings in tree trunks, which they described as "subfossils," reflect major changes in the environment, so they can be helpful when looking for clues to what happened in the past.

The rings of one of the trees sampled – a species known as Scots pine, Scotch pine or Baltic pine – suggested there was a "spike" in radiocarbon levels about 14,300 years ago. The team then compared this sample with a sample taken from Greenland's ice cores to confirm whether the radiocarbon could be tied to a "massive" solar storm.

Tree rings of a buried subfossil tree in the Drouzet river. (Cécile Miramont)

Edouard Bard, a professor of climate and ocean evolution at the Collège de France and CEREGE and lead author of the study, said that radiocarbon is constantly being produced through chain reactions.  

"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," Bard said in a press release about the study.

Based on the Alps and Greenland samples, it appeared that what they were seeing was evidence of a major solar storm, researchers said.

WHY DOES THIS MATTER?

"Radiocarbon provides a phenomenal way of studying Earth’s history and reconstructing critical events that it has experienced," Tim Heaton, professor of applied statistics at the School of Mathematics at the University of Leeds, said in a news release about the storm's discovery.

Researchers said if a solar storm of this magnitude were to happen today it would be "catastrophic" for modern society, with the potential to wipe out telecommunications, satellites and electricity grids —costing us billions.

"A precise understanding of our past is essential if we want to accurately predict our future and mitigate potential risks," according to Heaton.

He did not explain how this information can be used to make predictions.

The largest recorded solar storm in human history happened in 1859. Known as the Carrington Event, it caused "massive" disruptions to infrastructure.

According to researchers involved in this study, that solar storm impacted "telegraph machines and created a night-time aurora so bright that birds began to sing, believing the Sun had begun to rise."

Artist illustration of events on the sun changing the conditions in Near-Earth space. (NASA )

But this event was much smaller than previous solar storms scientists say they've been able to confirm from the ancient past, including the storm they believe happened 14,300 years ago.

"We do not know what causes such extreme solar storms to occur, how frequently they might occur, or if we can somehow predict them," researchers said in the news release.

But understanding the magnitude of which they can occur is part of the reason why researchers say they are excited about discovering what they call the largest solar storm to date.

"We still have much to learn," Heaton said. "Each new discovery not only helps answer existing key questions but can also generate new ones."