Strongest Solar Storm Ever 'Establishes a New Worst-Case Scenario'

New research has pinpointed the exact date when the strongest ever solar particle storm hit the Earth.

This identification of the event, which occurred in 12,350 B.C., rewrites what scientists considered possible when it comes to extreme space weather.

"Compared to the largest event of the modern satellite era—the 2005 particle storm—the ancient 12350 BC event was over 500 times more intense, according to our estimates," said paper author and physicist Kseniia Golubenko of Finland's University of Oulu in a statement.

At the core of this discovery is SOCOL:14C-Ex, a novel chemistry–climate model developed by Golubenko and fellow Oulu astrophysicist professor Ilya Usoskin.

Designed to reconstruct solar particle events under ancient glacial climate conditions, the model allowed the international team to pinpoint and assess an extreme radiocarbon spike during the waning stages of the last Ice Age.

"This event establishes a new worst-case scenario," Golubenko said in a statement.

"Understanding its scale is critical for evaluating the risks posed by future solar storms to modern infrastructure like satellites, power grids, and communication systems."

Their analysis confirmed that the event was about 18 percent stronger than previous record-holder, a storm in AD 775 recorded in tree-ring records . Other notable solar particle storms have occurred in 7,176 B.C., 5,259 B.C., 663 B.C. and 994 A.D.—but none came close to the ferocity of the newly-identified ancient event.

The discovery was made possible through radiocarbon measurements of wood samples recently unearthed in the French Alps dating back some 14,300 years.

While earlier observations had noted a significant increase in radiocarbon from that era, scientists lacked a reliable model to interpret the magnitude of the event—until now.

The SOCOL:14C-Ex model was validated using known data from the AD 775 storm and successfully extended to simulate late Ice Age conditions. This validation across both Holocene and glacial periods marks a critical step forward in analyzing radiocarbon anomalies from different climatic and geomagnetic time periods.

What Are Solar Storms?

Solar particle storms, while rare, pose a significant risk to modern technology. When they occur, these sudden explosions of energy, magnetic fields and material blast Earth with high-energy particles that can disrupt satellites, navigation systems, aviation, and power grids.

The infamous Carrington Event of 1859, often cited as the worst-case scenario for solar storms, was not a particle storm. This distinction matters because particle storms can have even more widespread atmospheric effects, and the new findings revise our understanding of solar physics and such space weather extremes.

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Reference

Golubenko, K., Usoskin, I., Rozanov, E., & Bard, E. (2025). New SOCOL:14C-Ex model reveals that the Late-Glacial radiocarbon spike in 12350 BC was caused by the record-strong extreme solar storm. Earth and Planetary Science Letters, 661, 119383. https://doi.org/10.1016/j.epsl.2025.119383