As the world grapples with the consequences of climate change, researchers have uncovered a significant clue in Italian limestone that helps explain a mass extinction of marine life millions of years ago during the Jurassic Period. This discovery may offer valuable insights into the impact of oxygen depletion and climate change on today’s oceans.
Michael A. Kipp, an assistant professor of earth and climate science at Duke University, co-authored a study measuring oxygen loss in oceans leading to marine species extinction 183 million years ago. “This event, and events like it, are the best analogs we have in Earth’s past for what is to come in the next decades and centuries,” he said.
During the Jurassic Period, extensive volcanic activity in what is now South Africa released approximately 20,500 gigatons of carbon dioxide (CO2) over 500,000 years, heating the oceans and causing significant oxygen depletion. The result was a mass extinction of Jurassic marine species due to suffocation from the lack of oxygen.
“It’s an analog, but not a perfect one, to predict what will happen to future oxygen loss in oceans from human-made carbon emissions, and the impact that loss will have on marine ecosystems and biodiversity,” said co-author Mariano Remirez, an assistant research professor at George Mason University.
By examining limestone sediment that carries chemicals dating back to the time of the volcanic activity, researchers were able to estimate changes in ancient ocean oxygen levels. At one point, oxygen was completely depleted in up to 8% of the ancient global seafloor, an area roughly three times the size of the United States.
Since the Industrial Revolution, human activity has released CO2 emissions equivalent to 12% of what was released during the Jurassic volcanism. However, Kipp notes that today’s rapid rate of atmospheric CO2 release is unprecedented, making it difficult to predict when another mass extinction might occur or its severity.
“We just don’t have anything this severe,” Kipp said. “We go to the most rapid CO2-emitting events we can in history, and they’re still not rapid enough to be a perfect comparison to what we’re going through today. We’re perturbing the system faster than ever before.”
“We have at least quantified the marine oxygen loss during this event, which will help constrain our predictions of what will happen in the future,” he concluded.
