Are We Underestimating the Threat of Solar Storms? A ‘Once-in-a-Thousand-Year’ Disaster Is Worth Considering, Scientists Say
The most powerful solar storms to strike Earth may pack a bigger punch than scientists realized, according to a new study that suggests the impacts of extreme space weather have been systematically underestimated.
Published in Nature on July 15, the research challenges a long-held assumption about geomagnetic storms: that there is an upper limit to how intense they can become. The apparent ceiling, the team found, is not a physical constraint but an artifact of where measurements are taken.
Where measurements fall short
Most solar wind measurements come from spacecraft stationed at Sun-Earth Lagrange Point 1 (L1), roughly 1.5 million kilometers (about 930,000 miles) upstream of Earth, directly between our planet and the Sun. At this distance, the strongest solar wind has already begun to weaken and dissipate before it ever reaches Earth’s vicinity. The data from L1 therefore makes it appear that Earth’s upper atmosphere stops responding beyond a certain threshold — a conclusion the new study shows is incorrect.
The team analyzed more than 1 million solar wind measurements taken by NASA spacecraft orbiting much closer to Earth, at the altitude where the solar wind directly interacts with our planet’s magnetic field. The results were clear: electrical currents in the upper atmosphere continued to intensify with stronger solar wind, with no sign of an upper limit.
“Our planet’s magnetic field does a really great job of protecting us against many space weather effects, and so they often just show up as glitches or beautiful aurora,” said Maria Walach, co-author of the study at Lancaster University. “There are, however, extreme cases.”
What this means for modern technology
A once-in-a-thousand-year solar storm could now generate geomagnetic disturbances far stronger than earlier models predicted. For a society increasingly dependent on satellites, power grids, and communications networks, the finding carries real consequences.
The Carrington Event of 1859, the strongest geomagnetic storm on record, disrupted telegraph systems worldwide and produced auroras visible as far south as the tropics. A storm of similar intensity today could disable satellite electronics, knock out GPS navigation for days, and cause widespread power grid failures. The Quebec grid collapse of 1989, triggered by a much milder storm, left millions without electricity. The Halloween storms of 2003 disrupted satellites and communications.
The May 2024 geomagnetic storm, the strongest in more than 20 years, produced spectacular auroras across much of the United States and Europe but caused only intermittent disruptions — a reminder that even moderate storms can affect modern infrastructure.
“Fortunately, these very extreme cases are rare, but this also means we have limited data to work with, and only time will tell what happens at the very extreme one-in-a-thousand-year kind of event,” Walach said.
A timely reminder
The Sun is currently near the peak of its roughly 11-year solar cycle, with sunspots, solar flares, and coronal mass ejections occurring at elevated frequency. The study does not suggest that an unprecedented storm is imminent, but it argues that scientists and policymakers may need to rethink how they estimate the severity of the rarest events — a challenge that grows more urgent as humanity’s dependence on space-based technology deepens.
Image credit: NASA/SDO