Some of the world’s oldest trees are revealing a surprising warning about the sun: our star is capable of producing solar storms far more powerful than anything humans have experienced in modern times.
The discovery began in 2012, when Japanese researcher Fusa Miyake studied ancient cedar tree rings from Yakushima Island.
Trees add a new ring each year, and those rings preserve traces of the atmosphere at the time they formed.
Miyake noticed something extraordinary in a ring dating to AD 775. The amount of radioactive carbon-14 suddenly jumped far beyond normal levels. The increase was about 20 times greater than ordinary variations associated with solar activity.
At first, scientists wondered whether the result was an error or something unique to Japanese trees. But the same signal was later found in trees from Europe and North America. Ice cores also contained supporting evidence. Something powerful had affected Earth’s entire atmosphere.
Researchers eventually concluded that an extreme burst of energetic particles from the sun was the most likely explanation.
These enormous events are now known as Miyake events. Scientists have identified several of them in ancient tree rings, including an exceptionally powerful event dating to around 12,350 BC.
They appear to dwarf even the famous Carrington event of 1859, the strongest solar storm directly observed in modern history. That storm produced auroras far from the poles and caused electrical problems in telegraph systems. Yet it was apparently not powerful enough to leave an obvious carbon-14 spike in tree rings.
A Miyake event could be roughly an order of magnitude more extreme. Fortunately, such events appear to be rare, perhaps occurring roughly once every couple of thousand years.
But researchers are increasingly interested in another possibility: smaller but still extremely powerful solar storms that may happen much more frequently.
A 2026 study in Communications Earth & Environment examined high-resolution carbon-14 records from tree rings covering most of the first millennium AD. Researchers identified four possible intermediate events around AD 14, 553, 675 and 954. If confirmed, storms in this middle category might occur roughly once every 200 years.
For today’s highly connected civilization, that possibility matters.
If such an event involved a huge coronal mass ejection—a cloud of electrically charged material thrown from the sun—it could disturb Earth’s magnetic field and generate damaging electrical currents in power grids, pipelines and other infrastructure.
A powerful solar flare could cause different problems. Earth’s atmosphere would protect people on the ground from much of the radiation, but satellites would be vulnerable. GPS, radio communications and other space-based technologies could be disrupted.
Determining exactly how often these events occur remains difficult because tree rings are imperfect recorders. Carbon-14 produced high in the atmosphere takes time to reach trees, while different species and growing seasons can blur the signal.
Researchers are therefore expanding their search around the world, including ancient kauri trees from New Zealand, which could provide valuable records from the Southern Hemisphere.
The work is changing scientists’ understanding of what the sun can do. Before Miyake’s discovery, few researchers thought our star could produce particle storms of such extraordinary strength.
Ancient trees have now shown that it can. The unanswered question is when the next enormous solar storm will arrive—and whether our technology will be ready for it.
