Projected CO2 Emissions Similar to Those Released by Volcanoes During Mass Extinction Event 200 Million Years Ago

Pulses of volcanic eruptions during a mass extinction event 200 million years ago produced the same amount of carbon dioxide as is predicted to be emitted over the 21st century, a study has found. A single pulse, they say, would have produced enough CO2 to warm the planet by around 2 degrees Celsius, and led to ocean acidification, causing similar changes to those predicted for Earth in the near future.

The end-Triassic mass extinction event 201 million years ago wiped out around 76 percent of all terrestrial and marine species on Earth. While the cause of the extinction event is not well understood, it is thought that huge volcanic eruptions in what is now the Atlantic Ocean led to a massive increase in carbon dioxide, resulting in major climatic changes. Sea levels rose, the ocean became more acidic and global temperatures increased. This event is thought to have given the dinosaurs, which had appeared around 40 million years earlier, the boost to become Earth's dominant species.

In a study published in Nature Communications, a team of scientists led by Manfredo Capriolo, from the University of Padova, Italy, has now examined the volcanic eruptions at the Central Atlantic Magmatic Province (CAMP) to work out how much CO2 was emitted at the end of the Triassic period.

This volcanic area is huge, covering around 4.2 million square miles, and eruptions at the site lasted around a million years. CAMP is mostly composed of basalt, a type of igneous rock, that formed before the supercontinent Pangea broke up.

The team analyzed these basaltic rocks from CAMP from the end-Triassic period, looking at bubbles of gas preserved in melt inclusions—small blobs of magma that have been trapped by crystals. This allowed the team to work out how abundant CO2 was released by these volcanic eruptions.

Findings suggest that eruptions took place during "pulses," each lasting from a few centuries to a few thousand years each. "Such short and powerful eruptions may have had a severe impact on global climate by limiting the time in which negative feedback processes...can abate warming and acidification," they wrote.

They estimate that each pulse released around the same amount of CO2 as is projected to be emitted from anthropogenic sources over the 21st century. With each pulse, global temperatures would have increased by about 2 degrees Celsius, and the ocean would have got more acidic. "It is possible that just a single CAMP volcanic pulse may have severely affected the end-Triassic climate," the study said.

Concluding, the authors add: "The end-Triassic climatic and environmental changes, driven by CO2 emissions, may have been similar to those predicted for the near future."

David Bond, from the U.K.'s University of Hull, whose research focuses on environmental changes during mass extinctions and who was not involved in the latest study, commented on the findings. He told Newsweek the paper was important as it helps fill gaps in our understanding of the role of large igneous provinces (LIP), like CAMP, and mass extinctions. "Even the extinction of the non-avian dinosaurs was partly a consequence of volcanism," he said.

"There is little doubt that some LIPs cause mass extinctions. However, there are examples of huge LIPs that do not seem to have given a 'deadly kiss' to life on Earth. This paper by Capriolo and colleagues helps explain why some LIPs are deadly, while others are not. They look inside the anatomy of a killer, through a case study of the enormous CAMP."

He said the finding that an eruption pules over 500 years delivered about the same amount of CO2 as human activity in the 21st century was reasonably. "If the CAMP eruptions caused global warming, ocean acidification and extinction, then the reasoning is that human-induced climate change could too," Bond said. "For context though, it is worth bearing in mind that the Permian-Triassic extinction, the greatest of mass extinctions around 250 million years ago, is associated with a rapid warming of up to 15 degrees Celsius. Humans, like the CAMP, will not deliver that sort of warming, but as Capriolo's study shows, there are many nuances in the LIP-CO2-warming-extinction nexus that we are only just beginning to understand. Their study should send an important message to our policy makers—CO2 has driven some of the greatest extinctions in Earth history."

This article has been updated to include comments from David Bond.