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Paleontologists call it the Permian-Triassic mass extinction, but it has another name: “the Great Dying”. This happened about 252 million years ago, and in the span of a few tens of thousands of years, 96% of all life in the oceans and, perhaps, about 70% of all earthly life are gone forever.
The smoking gun was an ancient volcanism in what is now Siberia, where volcanoes have disgorged enough magma and lava for about a million years to cover an area equivalent to a third or even half of the area of the United States.
But volcanism alone did not cause the extinction. The Great Dying was fueled, two separate teams of scientists report in two recent papers, by vast deposits of oil and coal that Siberian magma passed through, leading to combustion that released greenhouse gases like dioxide. of carbon and methane.
“There was a lot of petroleum, coal and carbonates formed before the underground extinction near Siberian volcanism,” said Kunio Kaiho, a geochemist at Tohoku University in Sendai, Japan, and senior author of one of the studies, published this month in Geology, which presented evidence of the burning of ancient fossil fuels by magma. “We discovered two volcanic combustion events coinciding with the extinction of land at the end of the Permian and the marine extinction.”
The results confirm that the Great Dying is one of the best examples we have in Earth’s history of what a changing climate can do for life on our planet.
Dr Kaiho and his team recovered samples of rock deposits from southern China and northern Italy that formed at the time of the extinction, and they detected spikes of a molecule called coronene. This substance, Dr Kaiho explained, is only produced when fossil fuels burn at extremely high temperatures – like those you might find in magma.
One potential problem with the coronene, says Henrik Svenson, a University of Oslo geologist who was not involved in the work, is that it only forms at temperatures above 2,100 degrees Fahrenheit, and for reach such temperatures, the fossil fuels should have been shrouded inside the magma, not just sitting next to it.
But the team’s findings are supported by a Nature Geoscience study released last month that presents chemical evidence for ocean acidification after fossil fuel combustion and greenhouse gas release.
As the planet warmed, the oceans absorbed more and more carbon dioxide. This caused the waters to acidify to the point where organisms like corals dissolved, said Hana Jurikova, a biogeochemist at the University of St. Andrews in Scotland who led the study. Dr Jurikova and his team discovered spikes of the element boron – an indicator of acidity levels – in fossil brachiopod shells found in rocks in Italy that stretch across the extinction boundary.
“For the first time, we are able to explain what caused the extinction,” said Dr Jurikova. “If you just turn up the temperature, organisms often find a way to cope. But the problem is, if you really change the temperature and the acidification, and maybe the nutrients, then your organisms won’t be able to adapt. Today, with rising sea surface temperatures, the oceans are acidifying and some shelled animals are already showing signs of their shells dissolving.
Dr Svenson believes the next step for geologists is to work on the ground in Siberia to determine if ancient magma interacted with the fossil fuel deposits, as the new studies imply.
“We just don’t know a lot of things,” Dr Svenson said.
While you might be tempted to draw an analogy between the Great Dying and current global warming, there are some significant differences. For one thing, the greenhouse gases emitted during the Permian Triassic events were far greater than anything humans produced. Additionally, volcanoes released carbon dioxide 252 million years ago at a much slower rate than humans emit today.
“The amount of carbon released into the atmosphere each year from the Siberian traps was still 14 times lower than the rate we have now,” said Dr Jurikova. “So the amount of carbon we are burning each year right now is much higher than during the Greatest Extinction. I mean, it’s amazing, right?
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