Researchers identify biggest ever solar storm in ancient tree rings

Following the analysis of ancient tree rings in the Southern French Alps, scientists have identified a huge spike in radiocarbon levels caused by a massive solar storm, the biggest ever identified. A solar storm of this magnitude could have potentially wiped out telecommunications and satellite systems, causing massive electricity grid blackouts, costing billions of pounds to the modern technological society.

The team, which involved researchers from the Collège de France, CEREGE, IMBE, Aix-Marseille University and the University of Leeds, measured radiocarbon levels in ancient trees preserved within the eroded banks of the Drouzet River, near Gap, in the French Alps.

Analysis of the individual tree rings identified a colossal spike in radiocarbon levels occurring precisely 14,300 years ago. The team then compared this spike with measurements of beryllium, a chemical element found in Greenland ice cores, and proposed that it was caused by a massive solar storm that would have ejected huge volumes of energetic particles into Earth's atmosphere. 

Such super solar storms are known as Miyake Events and very little is known about them as they have never been directly observed instrumentally. So far, only nine events have been identified, with the most recent confirmed occurring in 993 AD and 774 AD.

Scientists are yet to determine their exact nature - what causes such extreme storms to occur, how frequently they might occur, or if we can somehow predict them.

"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," said Edouard Bard, Professor of Climate and Ocean Evolution at the Collège de France and CEREGE, and lead author of the study.

More details are available here.