New research suggests that massive star explosions, known as supernovas, may have played a critical role in shaping Earth's ancient climate - and they could still pose a threat to our planet's atmosphere.
Scientists now believe that some of Earth’s past climate shifts and extinction events may have been triggered by radiation from nearby supernovas.
These cosmic events, which occur when massive stars collapse under their own gravity, release intense bursts of high-energy radiation capable of disrupting Earth’s atmospheric chemistry.
According to a report by Space.com, supernovas eject powerful streams of energy that, if close enough, could have dangerous consequences. “If such a blast occurred within 30 light-years, researchers warn, it could strip away Earth's atmosphere entirely.” Even explosions much farther away—like from Betelgeuse, a red supergiant star located 700 light-years from Earth—could still cause damage by disturbing climate patterns and increasing levels of harmful ultraviolet radiation reaching the surface.
Robert Brakenridge, senior researcher at the Institute of Arctic and Alpine Research, has been investigating this possibility using tree ring data. After analysing 15,000 years of growth patterns, he identified 11 spikes in radioactive carbon levels. “We have abrupt environmental changes in Earth's history,” Brakenridge explained. “We see these changes. So, what caused them?”
He believes these anomalies may be traces of cosmic radiation from distant supernovas. His model shows that the energy released could have severely damaged the ozone layer, exposing the Earth to increased ultraviolet rays. In addition, this radiation might have destroyed parts of the stratosphere rich in methane—an important greenhouse gas—potentially leading to sharp cooling and climatic shifts that could contribute to mass extinction events.
While solar flares have also been considered as possible sources of these carbon spikes, Brakenridge argues that more geological evidence, including ocean sediment and ice core data, could help confirm supernova involvement.
Understanding the link between stellar explosions and Earth’s environment could improve scientists' ability to forecast atmospheric disruptions if a nearby star—such as Betelgeuse—were to go supernova in the future.