Raging wildfires, acidified oceans and soaring temperatures likely caused a mass distinction 250 million years ago killing 95 percent of the Earth's marine life and 70 percent of terrestrial species.
Charles Henderson, a professor of geoscience at the University of Calgary, led the study that pinpointed more precisely than ever exactly when—252 million years ago—and for how long—about 20,000 years—the mass extinction happened.
The time frame, Henderson says, suggests the cause was massive volcano eruptions and the resulting carbon dioxide release from a region known as the Siberian Traps. Similar carbon dioxide releases have occurred before in Earth's history, and there's no reason it couldn't happen again.
"Certainly, the current concerns over global warming are related to greenhouse gases and we have become the 'new volcano,'" Henderson told me in an email. "Our study suggests that in the case of the End Permian extinction, high levels of CO2 were persistently detrimental to life for at least 20,000 years in order to achieve this largest extinction in Earth's history."
Henderson and a team of researchers studied 23 geological sites and 1,500 species of marine fossils. In particular, the teeth of tiny eel-like creatures called conodonts that lived in the Arctic and Western Canada provided a relative time scale based on their changing shape over time. They also looked at rocks and crystals, Henderson said:
We also correlated layers by determining the stable carbon isotopic signature of the rocks and this was very important to show the rapid environmental deterioration. … the absolute dates that were essential for this study were determined by the radioactive clocks found within tiny zircon crystals (about 0.1mm) that are found in numerous volcanic ash layers interbedded with the fossiliferous layers.
They used mass spectrometry to determine stable isotopic ratios and radioactive ages. And they studied the fossil species using a computer program called CONOP9, created by Pete Sadler at the University of California at Riverside.
It's kind of a big deal study that shows greenhouse gases can and did kill the earth. But a cataclysmic event like the one in the Permian isn't the only way it could happen. Enough years of carbon emissions will do the trick.
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