Paleontologists call it the Permian-Triassic mass extinction, but it has another name: “the great dying man.” It happened about 252 million years ago, and over the course of just tens of thousands of years, 96 percent of all life in the oceans and perhaps around 70 percent of all terrestrial life have disappeared forever.
The smoking gun was ancient volcanism in what is now Siberia, where volcanoes have spewed out enough magma and lava in about a million years to cover an amount of land equivalent to one-third or even half of the US surface .
But volcanism alone did not cause extinction. The Great Dying was fueled, as reported by two separate groups of scientists in two recent papers, by vast deposits of oil and coal through which Siberian magma exploded, leading to combustion that released greenhouse gases such as carbon dioxide and methane. .
“There was a lot of oil, coal, and carbonates formed before extinction in the subsurface near Siberian volcanism,” said Kunio Kaiho, a geochemist at Tohoku University in Sendai, Japan, and lead author of one of the studies, published this month in Geology, which presented evidence of the burning of ancient fossil fuels by magma. “We have discovered two volcanic combustion events that coincide with the Permian land extinction and marine extinction.”
The findings solidify the Great Dying as one of the best examples we have from Earth’s history of what a changing climate can do to life on our planet.
Dr. Kaiho and his team recovered samples from rock deposits in southern China and northern Italy that formed around the time of the extinction and detected peaks of a molecule called coronene. That substance, Dr. Kaiho explained, is only produced when fossil fuels burn at extremely high temperatures, such as you might find in magma.
A potential problem with coronene, says Henrik Svenson, a geologist at the University of Oslo who was not involved in the work, is that it only forms at temperatures above 2,100 degrees Fahrenheit, and to reach those temperatures, fossil fuels would have to be wrapped inside magma, not just sitting next to it.
But the team’s findings are supported by a Nature Geoscience study published last month that presents chemical evidence for ocean acidification after burning fossil fuels and releasing greenhouse gases.
As the planet warmed, the oceans absorbed more and more carbon dioxide. This caused the waters to acidify to the point that organisms such as corals would have dissolved, explained Hana Jurikova, a biogeochemist at the University of St Andrews in Scotland who led the study. Dr Jurikova and her team discovered spikes of the element boron – an indicator of acidity levels – in fossil shells found in rocks in Italy that extend beyond the extinction boundary.
“For the first time, we are able to explain what caused the extinction,” said Dr Jurikova. “If you just raise the temperature, organisms often find a way to cope. But the problem is that if you really change the temperature and the acidification, and perhaps the nutrients, then your organisms won’t be able to adapt. “Today, with rising sea surface temperatures, the oceans are changing. they are acidifying and some shelled animals are already showing signs of dissolution of their shells.
Dr Svenson thinks the next step for geologists is field work in Siberia to understand whether ancient magma interacted with fossil fuel deposits as the new studies imply.
“A lot of this we just don’t know,” said Dr. Svenson.
While you might be tempted to draw an analogy between the Great Dying and today’s warming climate, there are 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 by Siberian traps was still 14 times lower than the rate we have at the moment,’ said Dr Jurikova. “So, the amount of carbon we burn per year right now is much higher than during the largest extinction. I mean, it’s amazing, right? “