When the topic of extinction events is raised, a few immediate examples come to mind: the Chicxulub meteor that wiped out the dinosaurs, the Dutch-driven extinction of the dodo, or the demise of mammoths due to climate change. Yet none compare to the Permian-Triassic extinction — better known as “The Great Dying” — the single most catastrophic extinction event in Earth’s history.
An Extinction Event
A mass extinction is a biological catastrophe in which Earth’s biodiversity declines on a vast scale, with the rate of species loss far exceeding the rate of new species emerging.
It is thought that 99.999% of all life that has ever existed is now extinct. As National Geographic’s Michael Greshko notes:
“At least a handful of times in the last 500 million years, 75 to more than 90 percent of all species on Earth have disappeared in a geological blink of an eye in catastrophes we call mass extinctions.”
Life Before “The Great Dying”
The Permian world, 252 million years ago, was thriving. On land, insects buzzed and crawled, primitive dragonflies and cockroaches darted about, while large reptiles and amphibians grazed forests. Oceans teemed with fish, coral reefs flourished, and trilobites scuttled across the seafloor.
Science Alert describes the setting:
“Our planet was a very different place during the geological period referred to as the Permian. Before the Great Dying, a vast expanse of ocean dominated the surface, surrounding a single continent named Pangaea.”
Geochronologist Seth Burgess put it starkly:
“It looked like business as usual until all of a sudden, everything changed.”
Devastation of “The Great Dying”
Around 252 million years ago, the Permian-Triassic Extinction Event struck. In it, 90% of Earth’s species vanished, making it the deadliest extinction ever recorded.
- 96% of marine life perished as oceans lost up to 76% of their oxygen.
- 70% of land species were wiped out.
- Coral reefs collapsed.
- Forests withered and took nearly 10 million years to regrow.
- Trilobites, survivors for almost 300 million years across 20,000 species, disappeared entirely.
The event was not instantaneous — it unfolded over 60,000 years, grinding ecosystems down. According to researcher Dr. Hana Jurikova:
“It took several hundreds of thousands to millions of years for the ecosystem to recover from the catastrophe, which profoundly altered the course of evolution of life on Earth.”
Live Science adds that it took 14 million years for ocean reefs to return to former levels.
The event marked the transition to the Triassic Period, reshaping life’s trajectory on Earth.
Theories for Causation
The precise cause of The Great Dying remains debated, but most scientists agree multiple factors combined to devastate life.
One of the strongest theories points to the Siberian Traps volcanic eruptions, which may have lasted up to two million years. They spewed out 720,000 cubic kilometres of lava and released 14.5 trillion tonnes of carbon.
The consequences were severe:
- Global sea and land temperatures rose by several degrees.
- Oxygen depletion suffocated marine life.
- Coral reefs and coastal ecosystems collapsed.
CBS News notes that researchers discovered coronene — a rare molecule formed when fossil fuel deposits are superheated — in rocks from Italy and China, evidence of massive volcanic combustion.
Professor Uwe Brand of Brock University concluded:
“Over the course of a million years, extensive volcanic activity in what is now Siberia flowed through cracks and crevices of sedimentary rocks, searing oil and gas deposits as it moved along, producing the coronene scientists recently discovered. Carbon dioxide concentrations during that time period are estimated to be a few thousand parts per million.”
For comparison, today’s CO₂ levels, already at their highest in millions of years, stand at 415ppm.
EarthSky adds that volcanic eruptions likely ignited coal seams, releasing mercury vapour into the atmosphere, leaving a toxic fingerprint of catastrophe.
Curtis Deutsch of the University of Washington explained bluntly:
“Once you get to 3-4C of warming, that’s a significant fraction, and life in the ocean is in big trouble. It’s a very strong argument that rising temperatures and oxygen depletion were to blame.”
The consensus: a lethal cocktail of volcanic activity, climate change, oxygen loss, and toxic gases combined to nearly erase life on Earth.
Epilogue
“The Great Dying” almost ended all life, but in doing so, it cleared the evolutionary stage for what came next. Just as the later dinosaur extinction allowed mammals to flourish, the Permian event paved the way for entirely new ecosystems to rise.
Much remains unknown, but what is certain is its scale — unparalleled in Earth’s history. Another mass extinction, scientists warn, is inevitable; the only question is when.
As Curtis Deutsch warns:
“The very same things that caused the Great Dying are happening right now in our ocean today as a result of human activities — not to the same degree, but in the same direction.”
The lesson of the Permian extinction is clear: climate, carbon, and ecosystems are fragile — and when they collapse, the consequences are unimaginable.