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While many focus on the extinction of the dinosaurs as a pivotal moment in Earth’s history, an even more catastrophic event known as the “Great Dying” or the “End-Permian Extinction” predates it by millions of years. Recent research has revealed how this catastrophic event, which occurred approximately 250 million years ago, led to the extinction of over 90% of all life on Earth.
The primary trigger for this event was a series of enormous volcanic eruptions in present-day Siberia, referred to as the “Siberian flood basalts.” Astonishingly, these eruptions persisted for about one million years, reshaping the planet’s biosphere.
Michael Broadley, the lead author of the study and a postdoctoral researcher at the Centre for Petrographic and Geochemical Research in Vandœuvre-lès-Nancy, France, shed light on what made this extinction event particularly extraordinary:
“The magnitude of this extinction event is so staggering that it has led scientists to question why the Siberian Flood Basalts were particularly lethal compared to other volcanic eruptions,” Broadley noted.
Indeed, this mass extinction had a profound impact not only on larger terrestrial animals, wiping out around 70% of them, but it also decimated 96% of marine species and countless insect populations. The resulting loss of biodiversity was so severe that it took an additional 10 million years for ecosystems to recover fully.
So, what caused this devastation? Geologists suggest that the scale of the volcanic activity was so immense that it effectively obliterated the Earth’s ozone layer at that time. This conclusion was reached through an analysis of the lithosphere—the planet’s solid outer layer, which includes both the crust and the upper mantle. Prior to the eruptions, the Siberian lithosphere was rich in halogen elements like chlorine, bromine, and iodine. These substances, when inhaled, are highly toxic and often fatal. However, following the eruptions, there was a noticeable disappearance of these elements.
“Our findings indicate that the vast reserves of halogens stored in the Siberian lithosphere were released into the atmosphere during the volcanic eruptions, leading to the destruction of the ozone layer at that time and facilitating the mass extinction,” Broadley explained further.
Broadley’s investigation into this phenomenon, also known as the “Permian-Triassic extinction,” was conducted with the assistance of Lawrence (Larry) Taylor, who co-authored the study and served as the former director of the Planetary Geosciences Institute at the University of Tennessee, Knoxville. Taylor, a distinguished scientist with a career spanning 46 years, passed away in September 2017 at the age of 79.
