Most intense solar storm ever recorded hit Earth 14,300 years ago

A colossal burst of solar radiation struck Earth 14,300 years ago, showering the planet with high-energy particles and leaving behind an unmistakable spike in radiocarbon. Until now, scientists could not gauge the true scale of that ancient storm.

A newly developed chemistry-climate model, SOCOL:14C-Ex, has changed that – showing the Ice-Age event to be the most intense solar storm ever identified. It was 18 percent stronger than the famous AD 775 outburst and more than 500 times the power of any particle storm recorded by modern satellites.

Hidden signals in tree rings

Researchers first noticed an abrupt jump in radiocarbon (14C) concentrations for the year 12350 BCE when they analyzed larch trunks preserved beneath Alpine glaciers.

Such sharp rises, called Miyake events, occur when torrents of charged particles collide with the upper atmosphere, supercharging the natural production of cosmogenic isotopes.

Similar spikes near 775 CE and 994 CE have already revolutionized archaeological dating. The Ice-Age signal, however, lay outside the warm-climate Holocene epoch, and existing models could not simulate isotope chemistry under glacial conditions.

That impasse motivated postdoctoral scientist Kseniia Golubenko and professor Ilya Usoskin at the University of Oulu, Finland, to create SOCOL:14C-Ex.

The model couples atmospheric circulation, photochemistry, and radiocarbon pathways, then plugs in ancient ice-sheet boundaries, lower sea levels and a weaker geomagnetic field. Validated against the well-studied CE 775 event, the framework was ready for the Late-Glacial mystery.

Quantifying the Ice Age blast

Running the 12350 BC data through SOCOL:14C-Ex revealed particle fluxes dwarfing anything in the satellite era.

“Compared to the largest event of the modern satellite era – the 2005 particle storm – the ancient 12350 BCE event was over 500 times more intense, according to our estimates,” Golubenko said.

The model puts the radiation spike 18 percent above the CE 775 benchmark, establishing a new solar ceiling. Other intense solar storms are known – around 663 BCE, 5259 BCE and 7176 BCE – yet none match this Ice-Age titan.

“The ancient event in 12350 BCE is the only known extreme solar particle event outside of the Holocene epoch, the past ~12000 years of stable warm climate,” Golubenko stated. That fact alone widens the time frame scientists must consider when assessing solar variability.

A tool for radiocarbon dating

Radiocarbon researchers often struggle to convert “floating” chronologies – relative sequences with no fixed calendar anchor – into absolute timelines. Sudden global 14C surges are perfect anchors.

“Miyake events allow us to pin down exact calendar years in floating archaeological chronologies,” Usoskin explained.

The new Late-Glacial marker could help synchronize disparate records from the waning Ice Age: cave-paint dates, retreating ice margins, even megafaunal extinctions.

SOCOL:14C-Ex also frees scientists from the Holocene boundary, letting them mine older wood, peat, and stalagmite archives for yet-undetected spikes. The possibility of mapping a full 30,000-year record of solar storms has now moved within reach.

Risks of intense solar storms

Until this study, theorists debated whether the AD 775 storm represented a physical upper limit for solar particle acceleration. The Ice-Age event proves the Sun can exceed that benchmark.

“This event establishes a new worst-case scenario,” Golubenko noted. “Understanding its scale is critical for evaluating the risks posed by future solar storms to modern infrastructure like satellites, power grids, and communication systems.”

Modern civilization has never faced anything close to the Ice-Age blast. The 1989 Quebec blackout came from a geomagnetic storm far weaker; the Carrington flare of 1859, often cited as a dire warning, did not involve a massive particle shower.

A repeat of the 12350 BCE storm today could cripple satellite constellations, corrupt navigation signals, and overload long-distance transmission lines.

A collaborative effort across disciplines

The study  brings together geophysicists, atmospheric chemists and dendrochronologists from Finland, France, and Switzerland under the leadership of Edouard Bard of the CEREGE.

The research blended laboratory isotope measurements, supercomputer modeling, and cross-checks against newly unearthed timber from the French Alps.

After confirming the Ice-Age spike’s magnitude, the team calculated its climatic footprint. Although the particle deluge doubled stratospheric ionization rates for months, temperature effects appear minimal, mirroring results from younger Miyake events.

The principal legacy is the radiocarbon “barcode” now locked into prehistoric archives worldwide.

Hunting for older solar storms

With SOCOL:14C-Ex validated for glacial settings, Golubenko and colleagues plan to scan older growth rings and polar ice for further anomalies. Each discovery will refine models of solar dynamics and help planners gauge the rare but existential threat posed by extreme space weather.

“Our new model lifts the existing limitation to the Holocene and extends our ability to analyze radiocarbon data even for glacial climate conditions.”

Armed with that capability, scientists can now track the Sun’s wildest moods across multiple ice ages, offering both a clearer view of our star’s potential and a sterner test for the resilience of modern technology.

The study is published in the journal Earth and Planetary Science Letters.

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