The largest mass extinction in Earth’s history linked to climate chaos

A new study links the largest mass extinction, which occurred 252 million years ago during the Permian-Triassic period, to climate warming resulting in extreme weather events.

Scientists have long linked the Permian-Triassic mass extinction to massive volcanic eruptions in what is now Siberia. Large emissions of carbon dioxide rapidly accelerated climate warming, causing widespread ocean acidification, the collapse of ocean currents, and resulting in the loss of about 96 percent of all marine species. But it was not clear why terrestrial ecosystems also suffered so much, with an estimated loss of 75 percent of all land-living species.

A new study, co-authored by an international and multidisciplinary team of scientists, has shed new light on why the Permian-Triassic warming was so devastating to all forms of life in the sea and on land.

Co-author Dr. Alexander Farnsworth, senior research fellow at the University of Bristol, explains that, “climate warming alone cannot drive such devastating extinctions because, as we are seeing today, when the tropics get too hot, species migrate to colder ones. , higher latitudes.”

“Our research has found that rising greenhouse gases not only make most of the planet warmer, but also increase the variability of weather and climate, making it even more ‘wild’ and harder for life to survive.”

The rate of Permian-Triassic warming was discovered 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 exceptionally high temperatures at low and mid-latitudes, resulting in chaotic ocean circulation patterns. The large land mass formed by the supercontinent Pangaea, trapping heat, added to the rising temperatures.

“Basically, it got too hot everywhere. The changes responsible for the climate patterns identified were profound because there were far more intense and prolonged El Niño events than are seen today. Species simply weren’t equipped to adapt or evolve enough fast,” Farnsworth concludes.

In recent years, El Niño events have caused major changes in rainfall and temperature patterns. For example, the weather extremes that caused the North American heat wave of June 2024, when temperatures were about 15 degrees warmer than normal. The period between 2023-2024 was also one of the hottest on record globally due to a strong El Niño in the Pacific, which was further exacerbated by increased human-caused carbon dioxide causing drought and catastrophic fires around the world. Rising temperatures are also linked to mass die-offs of marine animals and coral bleaching.

“Thankfully, such events have so far lasted only one to two years at a time. During the Permian-Triassic crisis, El Niño continued for much longer, resulting in a decade of widespread drought, followed by years of whole floods. Basically, the climate was all over the place and that makes it very difficult for any species to adapt,” explains co-author Paul Wignall, Professor of Paleoenvironments at the University of Leeds.

“Fires become very common if you have a drought-prone climate. The Earth got stuck in a state of crisis where the land was burning and the oceans were stagnating. There was nowhere to hide,” adds co-author Professor David Bond, a palaeontologist at the University of Hull. .

The researchers noted that throughout Earth’s history there have been many volcanic events similar to those in Siberia, and many of them caused extinctions, but none led to a crisis on the scale of the Permian-Triassic event.

This extinction was so different because these Mega-El Niños created positive climate feedbacks that led to extremely warm conditions starting in the tropics and then, resulting in the fading 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 is one of Earth’s mechanisms to stop the build-up of carbon dioxide in the atmosphere as a result of ongoing volcanism. .

This hypothesis also helps explain why the extinction on land occurred tens of thousands of years before the mass extinction in the oceans.

“While the oceans were initially protected from rising temperatures, mega-El Niños caused temperatures on land to exceed the thermal tolerances of most species at such a rapid rate that they could not adapt in time. Only species that could migrate quickly could survive, and there weren’t many plants or animals that could do that,” explains co-author Professor Yadong Sun, at China University of Geosciences, Wuhan.

Extinction events on this scale, paleontologists recognize five major mass extinctions in the fossil record, are the heartbeat of Earth’s natural system that restores life and evolution along different paths.

“The Permo-Triassic mass extinction, although devastating, would eventually see the rise of dinosaurs becoming the dominant species afterwards, just as the Cretaceous mass extinction would lead to the rise of mammals and humans,” Farnsworth concludes.

Full Study”Mega El Niño triggered the end-Permian mass extinction” was published in the magazine Science.

Additional materials and interviews provided by the University of Bristol.