Space Weather News for Jan. 30, 2025
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WHAT ARE ‘MIYAKE EVENTS’? So you thought the Carrington Event was bad? Researchers have found evidence in tree rings of solar storms 10 times worse. The discovery of “Miyake Events” has placed dendrochronologists at the center of space weather research.
A WARNING FROM THE TREES: How bad can a solar storm be? Just ask a tree. Unlike human records, which go back hundreds of years, trees can remember solar storms for millennia.
Nagoya University doctoral student Fusa Miyake made the discovery in 2012 while studying rings in the stump of a 1900-year-old Japanese cedar. One ring, in particular, drew her attention. Grown in the year 774–75 AD, it contained a 12% jump in carbon-14 (14C), an isotope created by cosmic radiation. The surge was 20 times greater than ordinary fluctuations in cosmic rays. Other teams confirmed the spike in wood from Germany, Russia, the United States, Finland, and New Zealand. Whatever happened, trees all over the world experienced it.
Most researchers think it was a solar storm—an extraordinary one. Often, we point to the Carrington Event of 1859 as the worst-case scenario for solar storms. The 774-75 AD storm was at least 10 times stronger; if it happened today, it would floor modern technology. Since Miyake’s initial discovery, she and others have confirmed four more examples (7176 BC, 5259 BC, 664-663 BC, 993 AD). Researchers call them “Miyake Events.”
Right: The 774-775 AD carbon-14 spike. [more]
It’s not clear that all Miyake Events are caused by the sun. Supernova explosions and gamma-ray bursts also produce carbon spikes. However, the evidence tilts toward solar storms. For each of the confirmed Miyake Events, researchers have found matching spikes of 10Be and/or 36Cl in ice cores. These isotopes are known to trace strong solar activity. Moreover, the 774-75 AD Miyake Event had eyewitnesses; historical reports of auroras in China and England suggest the sun was extremely active around that time.
Miyake Events have placed dendrochronologists (scientists who study tree rings) in the center of space weather research. After Miyake’s initial discovery in 2012, the international tree ring community began working together to look for evidence of solar superstorms. Their collaboration is called “the COSMIC initiative.” COSMIC results published in a 2018 edition of Nature confirm that Miyake Events in 774-75 AD and 993 AD were indeed global. Trees on five continents recorded carbon spikes.
“There could be additional Miyake Events throughout the Holocene” says Irina Panyushkina, a member of the COSMIC initiative from the University of Arizona’s Laboratory for Tree-Ring Research. “Finding them will be a slow and systematic process.”
Above: A global map of COSMIC tree ring and ice core measurements [more]
“An important new source for annual 14C measurements are floating tree-ring records from Europe and the Great Lakes,” says Panyushkina. “These are very old rings that could potentially capture 14C spikes as far back as 15,000 years. Eventually, I believe we will have a complete record of Miyake Events throughout that period.”
Four more candidates for Miyake Events have recently been identified (12,350 BC, 5410 BC, 1052 C, and 1279 C). The candidate in 12,350 BC, identified from tree rings the French Alps, may be more than twice the size of any other Miyake Event. Confirmation requires checking trees on many continents and finding matching spikes of 10Be and 36Cl in ice cores.
A complete survey of Miyake Events could tell us how often solar superstorms occur and how much peril the sun presents to a technological society. Stay tuned for updates from the trees.