Appropriately, scientists nicknamed the event the “Great Dying” (also known in science speak as the “Permian-Triassic extinction”). But despite the magnitude of the disaster, only in the past two decades did paleontologists find clues of it in the fossil record—and discover it coincided with a massive volcanic event in modern-day Siberia.
Now, a new study published Thursday in the journal Science suggests the culprit of the Great Dying—and the connection between the two events—was likely something the planet is all too familiar with today: global warming, and, as a result, high ocean temperatures and a loss of oxygen in the water.
And, it turns out, this millions-year-old event might be able to serve as a warning for our own future. The authors write that the combination of those two factors—warming water and low oxygen—“can account for more than half the magnitude of the ‘Great Dying’” in the ocean. Both factors, of course, are still at play right now.
“These extreme events are so important because they give us some view—what are the limits of climate change?” Woodward Fischer, a professor of geobiology at Caltech who reviewed the paper and was not involved with the study, tells Mother Jones. “What are the limits of environmental change? And how do those feedback on the biosphere? It’s kind of like a way of asking, ‘Well, what is possible?’”
Here’s how the authors got their result: While scientists had long guessed a warming climate played a part in the Great Dying, they hadn’t come up with a way to prove it. In order to test the theory, the team simulated ancient global warming with a model of Earth’s climate and predicted how ocean warming and oxygen loss would affect where ancient marine species could survive, based on the tolerance levels of animals alive today, including fish, crustaceans, sharks, corals, and mollusks. It wasn’t a perfect model (no model is), but it served as an approximation of how sensitive ancient species may have been to a warming climate at the time. Then, to see how the model stood up, they compared it with the fossil record.
It performed spectacularly. Not only did it match up with the fossil record, but it even predicted something that paleontologists had never noticed: that creatures living near the equator were slightly more likely to survive a major warming event than ones near the poles. Presumably, those living at the equator could travel north to cooler waters as the temperatures rose, while those at the poles were trapped. (That’s not to say the tropics are a useful refuge; the majority of species still died there.)