Evidence of the most powerful solar storm in history has been uncovered in an unlikely place: within the rings of a tree.
This immensely powerful solar storm is thought to have been at least 10 times as powerful as the Carrington Event of 1859, which caused chaos in the rudimentary telegraph system of the time.
New research has now found that a radiocarbon spike found within ancient tree rings in the French Alps reveals the full extent of the sun's power, and the potential danger it poses to us if a storm of this scale occurs today, according to a study published in the journal Philosophical Transactions of the Royal Society A Mathematical Physical and Engineering Sciences.
"Extreme solar storms could have huge impacts on Earth," Tim Heaton, professor of applied statistics at the University of Leeds in England and co-author of the paper, said in a statement.
A team of 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 Southern French Alps.
Looking at the individual tree-ring allows researchers to reconstruct environmental and chemical changes for almost every year the tree lived. By stacking sections of many trees together, scientists can reconstruct a tree-ring record spanning many thousand years.
The researchers found a strange spike in radiocarbon within the rings of subfossilized trees dating to around 14,300 years ago. This spike was found to line up with patterns in beryllium levels in Greenland ice cores, indicating that the spike was caused by a huge solar storm.
"Radiocarbon is constantly being produced in the upper atmosphere through a chain of reactions initiated by cosmic rays," Edouard Bard, a professor of climate and ocean evolution at the Collège de France and CEREGE, and lead author of the study, said in the statement.
"Recently, scientists have found that extreme solar events including solar flares and coronal mass ejections can also create short-term bursts of energetic particles which are preserved as huge spikes in radiocarbon production occurring over the course of just a single year."
Solar storms like this one and the Carrington Event in 1859 are caused by solar flares, which are ejections of powerful X-rays from the sun.
"In general, a flare is a substantial release of energy from the sun and specifically an active region or sun spot," said Daniel Brown, an associate professor in astronomy and science communication at England's Nottingham Trent University.
"These are caused by magnetic field lines becoming more and more twisted storing energy like a rubber band, and at some stage, they snap and rearrange. That results in a massive release of electromagnetic radiation and also material from this region."
The Carrington Event, thought to be the most powerful solar storm in modern history, caused widespread impacts to infrastructure in 1859, and led to an incredibly bright aurora in the night sky.
"In that strongest ever Carrington Event there were reports of telegraph lines sparking with the voltages induced in them," Alan Woodward, a professor of computer science and space weather expert at England's University of Surrey. "If that were to happen today you can imagine just how much electronic equipment we depend upon and extrapolate how it is disruptive on earth."
A solar storm similar to the Carrington Event could lead to trillions of dollars worth of damages.
The solar storm measured in the tree rings is thought to be at least 10 times stronger than the Carrington Event, making it one of a class of extreme solar storms known as Miyake Events. Nine of these events have been identified as occurring in the last 15,000 years—the most recent of which occurred in 774 AD and 993 AD—but this new discovery may be the most powerful ever found.
This find therefore shows just how powerful the sun is capable of being, and the possibility that a powerful solar storm like that could once again hit the Earth in the future.
"Such super storms could permanently damage the transformers in our electricity grids, resulting in huge and widespread blackouts lasting months," Heaton said in the statement.
"They could also result in permanent damage to the satellites that we all rely on for navigation and telecommunication, leaving them unusable. They would also create severe radiation risks to astronauts."
Nine such extreme solar storms—known as Miyake Events—have now been identified as having occurred over the last 15,000 years studying tree-rings and ice layers records. This newly-identified 14,300-year-old storm is, however, the largest that has ever been found—roughly twice the size of the last two.
Today the National Oceanic and Atmospheric Administration’s Space Weather Prediction Center monitors solar activity and its impact on our infrastructure. Not appropriately shielded electronics are still at a high risk of interference and jamming. A similar massive event happening today could be catastrophic for our technology-based society.