World’s most powerful solar storm struck Earth 14,300 years ago, scientists say

A colossal solar storm struck Earth 14,300 years ago, making it the most powerful event of its kind ever detected, according to a new study. The discovery pushes back the known limits of solar activity and raises fresh questions about the risks posed by such space weather to modern infrastructure.

The storm, which occurred around 12,350 BC during the final stages of the last Ice Age, left a distinct spike in atmospheric radiocarbon levels — an isotopic signature preserved in ancient tree rings. Until recently, scientists had lacked the tools to accurately gauge the strength of such ancient solar events. But with the help of a new model, researchers have now confirmed the true intensity of the prehistoric event.

Researchers at the University of Oulu in Finland, led by postdoctoral scientist Kseniia Golubenko and professor Ilya Usoskin, developed a climate-chemistry model to reconstruct solar particle storms under glacial conditions. Their results showed that the Ice Age event was about 18 per cent stronger than the AD 775 solar storm, long regarded as the most extreme ever recorded in tree-ring archives.

“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,” Golubenko said in a press statement.

Solar particle storms are rare eruptions that shower the Earth with high-energy particles, triggering elevated levels of cosmogenic isotopes such as radiocarbon. These spikes, known as Miyake events, serve as cosmic timestamps that allow scientists to pinpoint exact years in otherwise floating archaeological chronologies.

The team validated their model using tree-ring data from the AD 775 event and applied it to newly analysed wood samples from the French Alps dating back more than 14,000 years. This approach allowed them to map the strength, timing and atmospheric impact of the 12,350 BC event—the first such extreme event found outside the Holocene, the roughly 12,000-year period of stable climate in which human civilisation emerged.

The study, published in the journal Earth and Planetary Science Letters, involved researchers from Finland, France and Switzerland and was led by professor Edouard Bard of CEREGE, France.

Known historical solar particle storms occurred in AD 994, 663 BC, 5259 BC, and 7176 BC, among others. The infamous Carrington event of 1859 — often cited in space weather discussions — was not a particle storm and belongs to a different category of solar phenomena.

The findings offer crucial insight into the solar system’s past and future. 

Usoskin added that these radiocarbon spikes offer a powerful tool for reconstructing ancient solar activity. “Miyake events allow us to pin down exact calendar years in floating archaeological chronologies.”

As solar activity continues to rise in the current solar cycle, the research has renewed urgency. While solar storms of this magnitude are exceedingly rare, their potential impact on modern technological society could be devastating.