It would potentially wipe out telecommunications and satellite systems, cause massive electricity grid blackouts, and cost the global economy billions of pounds.

Evidence of the biggest ever solar storm 14,300 years ago has been found in ancient tree rings. Such a massive storm today on the scale of the newly discovered one would be “catastrophic” for modern technology, say scientists.

It would potentially wipe out telecommunications and satellite systems, cause massive electricity grid blackouts, and cost the global economy billions of pounds. The research team say it is vitally important to understand the sun’s extreme behaviour and the risks it poses to Earth.

A huge “spike” in radiocarbon levels was identified by an international team of scientists who analysed ancient tree-rings found in the French Alps. Professor Tim Heaton, of the University of Leeds, said: “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. 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.” Nine such extreme solar storms – known as Miyake Events – have now been identified as having occurred over the last 15,000 years. The most recent confirmed Miyake Events occurred in 993 AD and 774 AD.

The newly-identified 14,300-year-old storm is, however, the largest that has ever been found – roughly twice the size of the two. in the Middle Ages. Scientists say the exact nature of those storms remains very poorly understood as they have never been directly observed instrumentally.

Prof Heaton added: “We do not know what causes such extreme solar storms to occur, how frequently they might occur, or if we can somehow predict them.” The research team measured radiocarbon levels in ancient trees preserved within the eroded banks of the Drouzet River, near Gap, in the Southern French Alps.

Study lead author Professor Edouard Bard, of the Collège de France, said: “Radiocarbon is constantly being produced in the upper atmosphere through a chain of reactions initiated by 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.”

The tree trunks, which are subfossils – remains whose fossilisation process is not complete – were sliced into tiny single tree-rings. Analysis of the individual rings identified an “unprecedented” spike in radiocarbon levels occurring precisely 14,300 years ago. By comparing the spike with measurements of beryllium, a chemical element found in Greenland ice cores, the team suggest that the spike was caused by a massive solar storm that would have ejected “huge” volumes of energetic particles into Earth’s atmosphere.

Prof Bard said: “Direct instrumental measurements of solar activity only began in the 17th Century with the counting of sunspots. 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 behaviour further back into the past.”

The largest, directly-observed, solar storm occurred in 1859 and is known as the Carrington Event. It caused massive disruption on Earth – destroying telegraph machines and creating a night-time aurora so bright that birds began to sing, believing the Sun had begun to rise.

But the Miyake Events – including the newly discovered 14,300-year-old storm – would have been a “staggering” entire order-of-magnitude greater in size. Prof Heaton added: “Radiocarbon provides a phenomenal way of studying Earth’s history and reconstructing critical events that it has experienced.