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A sixth mass extinction could be in the cards, according to MIT professor

An MIT professor says increasing carbon levels in the oceans could lead to the world’s sixth mass extinction event.
Jorge Guerrero/AFP/Getty Images
An MIT professor says increasing carbon levels in the oceans could lead to the world’s sixth mass extinction event.

Increasing carbon levels in the oceans could lead to the world’s sixth mass extinction event, according to a geophysics professor at the Massachusetts Institute of Technology.

Daniel Rothman recently published a paper in the journal “Science Advances” predicting that the world’s oceans could hold enough carbon by the year 2100 to trigger a sixth mass extinction in them, the university said in a statement Wednesday.

Rothman said that if nothing is done to prevent it, “the carbon cycle would move into a realm which would be no longer stable, and would behave in a way that would be difficult to predict. In the geologic past, this type of behavior is associated with mass extinction.”

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A mass extinction is a period when a large number of species become extinct. Perhaps the most well-known mass extinction occurred 65 million years ago and led to the disappearance of the dinosaurs.

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While disruptions in the carbon cycle seem to be an indicator of mass extinctions, science has yet to come up with precisely how they are linked, Rothman said in a telephone interview Monday afternoon.

“It’s been a longstanding scientific question,” Rothman said.

Rothman said there have been five mass extinction events in the past 450 million years, each of which lined up with changes in the way carbon dioxide cycles through the biosphere.

However, there have been other significant changes in the carbon cycle over that time, too, that haven’t resulted in mass extinctions, Rothman noted.

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Increased carbon emissions have raised fears of global warming through the greenhouse effect, but Rothman is focused on a different effect of the increased emissions.

He said that if 310 gigatons of carbon dioxide are added to the oceans, it could be a crucial tipping point for the carbon cycle.

“It doesn’t mean that that amount of carbon will create a mass extinction,” Rothman emphasized. “The carbon cycle becomes an indication of how the environment is changing. We can’t say whether it is a cause or an effect, but it’s a key player.”

Predictions from the Intergovernmental Panel on Climate Change indicate that humans will add 300 to 500 gigatons of carbon to the oceans by 2100, the university said.

Increases in the amount of carbon in the air and in the oceans would not cause a mass extinction or natural disaster immediately. The process would take thousands of years. But it’s not too early to consider the long-term effects of changes in the carbon cycle, Rothman said.

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“There are an enormous amount of reasons to care about modern environmental change. Global warming is an obvious one,” Rothman said. “This particular issue, mass extinction in the ocean related to CO2 levels, has received much less attention. We need to care about the destruction of life.”

Alyssa Meyers can be reached at alyssa.meyers@globe.com. Follow her on Twitter @ameyers_.