The end-Permian mass extinction, which occurred about 252 million years ago, was the most severe extinction event in the past 540 million years, eliminating more than 90% of marine and 75% of terrestrial species. Scientists have long linked this extinction to vast volcanic eruptions in what is now Siberia. The resulting carbon dioxide emissions rapidly accelerated climate warming, resulting in widespread stagnation and the collapse of marine and terrestrial ecosystems. But what caused life on land, including plants and usually resilient insects, to suffer just as badly has remained a source of mystery.
An illustration depicting the onset of the end-Permian mass extinction. Image credit: Dawid Adam Iurino / PaleoFactory, Sapienza University of Rome / Jurikova et al, doi: 10.1038/s41561-020-00646-4.
“Climate warming alone cannot drive such devastating extinctions because, as we are seeing today, when the tropics become too hot, species migrate to the cooler, higher latitudes,” said University of Bristol’s Dr. Alexander Farnsworth.
“Our research has revealed that increased greenhouse gases don’t just make the majority of the planet warmer, they also increase weather and climate variability making it even more ‘wild’ and difficult for life to survive.”
“The Permian-Triassic catastrophe shows the problem of global warming is not just a matter of it becoming unbearably hot, but also a case of conditions swinging wildly over decades.”
“Most life failed to adapt to these conditions, but thankfully a few things survived, without which we wouldn’t be here today. It was nearly, but not quite, the end of the life on Earth,” said China University of Geosciences Professor Yadong Sun.
The scale of end-Permian warming was revealed by studying oxygen isotopes in the fossilized tooth material of tiny extinct swimming organisms called conodonts.
By studying the temperature record of conodonts from around the world, the researchers were able to show a remarkable collapse of temperature gradients in the low and mid latitudes.
“Essentially, it got too hot everywhere,” Dr. Farnsworth said.
“The changes responsible for the climate patterns identified were profound because there were much more intense and prolonged El Niño events than witnessed today.”
“Species were simply not equipped to adapt or evolve quickly enough.”
A geological field section reveals a desiccated (extreme dryness) land surface that was common all over the world 252 million years ago. Image credit: University of Bristol / China University of Geosciences.
In recent years, El Niño events have caused major changes in rainfall patterns and temperature.
For example, the weather extremes that caused the June 2024 North American heatwave when temperatures were around 15 degrees Celsius hotter than normal.
2023-2024 was also one of the hottest years on record globally due to a strong El Niño in the Pacific, which was further exacerbated by increased human-induced carbon dioxide driving catastrophic drought and fires around the world.
“Fortunately such events so far have only lasted one to two years at a time,” said University of Leeds Professor Paul Wignall.
“During the Permian-Triassic crisis, El Niño persisted for much longer resulting in a decade of widespread drought, followed by years of flooding.”
“Basically, the climate was all over the place and that makes it very hard for any species to adapt.”
The results of the climate modeling also help explain the abundant charcoal found in rock layers of that age.
“Wildfires become very common if you have a drought-prone climate,” said University of Hull Professor David Bond.
“Earth got stuck in a crisis state where the land was burning and the oceans stagnating. There was nowhere to hide.”
The researchers observed that throughout Earth’s history there have been many volcanic events similar to those in Siberia, and many caused extinctions, but none led to a crisis of the scale of the end-Permian event.
They found the extinction was so different because these mega-El Niños created positive feedback on the climate which led to incredibly warm conditions starting in the tropics and then beyond, resulting in the dieback of vegetation.
Plants are essential for removing carbon dioxide from the atmosphere, as well as the foundation of the food web, and if they die so does one of the Earth’s mechanisms to stop carbon dioxide building up in the atmosphere as a result of continued volcanism.
This also helps explain the conundrum regarding the end-Permian mass extinction whereby the extinction on land occurred tens of thousands of years before extinction in the oceans.
“Whilst the oceans were initially shielded from the temperature rises, the mega-El Nino’s caused temperatures on land to exceed most species thermal tolerances at rates so rapid that they could not adapt in time,” Dr. Sun said.
“Only species that could migrate quickly could survive, and there weren’t many plants or animals that could do that.”
“The Permo-Triassic mass extinction, although devastating, would ultimately see the rise of dinosaurs becoming the dominant species thereafter as would the end-Cretaceous mass extinction lead to the rise of mammals, and humans,” Dr. Farnsworth said.
The results were published in the journal Science.
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Yadong Sun et al. 2024. Mega El Niño instigated the end-Permian mass extinction. Science 385 (6714): 1189-1195; doi: 10.1126/science.ado2030
