By reading the past in tree rings, an international team of researchers was able to discover that the largest solar storm ever known took place 14,300 years ago.
A solar storm occurs when the sun ejects enormous volumes of energetic particles into the Earth’s atmosphere. The largest solar storm known and observed so far was that of 1859, known as the Carrington Event. These energetic particles then led to the destruction of telegraph machines. And created a kind of glow, so much so, it is said, that in the middle of the night, it was possible to read the newspaper and certain birds began to sing, thinking it was morning. But an international scientific team involving the University of Leeds and the Collège de France has just established that there was an even more significant solar storm, 14,300 years ago.
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Their work published, Monday October 9, in a review of the British Royal Societyand spotted by our colleagues from the newspaper The world indicate that if a similar solar storm occurred today, it would destroy a large part of our communications systems, our satellites and create gigantic blackouts in the electrical grid.
Go back in time with trees
These researchers were able to go back this far in time and date this phenomenon by succeeding in reading this exceptional event in the trunks of prehistoric trees, originating from the Southern Alps. By cutting wood samples from each ring with a scalpel, they were able to go back in time and identify a carbon-14 peak, 14,300 years ago. Carbon-14 is known as a tool for dating archaeological objects over 55,000 years old; normally its quantity remains stable in the atmosphere. If additional carbon 14 is formed, underlines astrophysicist Éric Lagadec, it is because particles charged with energy have crossed the atmosphere from the sun. Knowledge of this exceptional event, more than 14,000 years old, provides new knowledge about the activity of the sun.
This is not the first time that tree trunks have allowed us to read the past. In a more traditional way, they are also useful for obtaining information on the climate of past centuries. In general, we go back less far in time but indeed the analysis of the rings in the trunks makes it possible to understand, year by year, the physiological functioning of the tree and therefore to see traces of drought, flooding, snow and even hurricanes.