The Next ‘Great Dying’ Is Coming for Your Seafood

Sergeant major damselfish swim around the corals off the shore of Koh Adang in the Andaman sea.

Sergeant major damselfish swim around the corals off the shore of Koh Adang in the Andaman sea.
Photo: Mladen ANTONOV / AFP (Getty Images)

Enjoy the teeming oceans… for now.

A new report in the journal Science finds that if climate change isn’t curbed, we stand to lose so much biodiversity in the world’s oceans that it will rival has massive navy die-off that occurred more than 250 million years ago. The prehistoric “Great Dying” was marked by the death of more than two-thirds of the species in the oceans at the time.

Tea researchers looked at several climate models, including one in which the world goes about business as usual instead of working to decarbonize our systems and stop global temperatures from rising. A high-emissions scenario means changes in ocean temperatures and oxygen levels—something that also occurred during the end-Permian extinction millions of years ago.

Models found that many species lose the habitats they need to survive, and the climate crisis will change migration patterns as well. The tropical oceans will lose a significant amount if existing biodiversity, and many species there will have to migrate north to survive future conditions. Polar species will probably disappear.

Study co-authors and geoscience professors at Princeton University Justin Penn and Curtis Deutsch explained that the projected extinction would happen over a period of about 200 years. Animals and eco-systems that are the most sensitive to changing oxygen levels and temperatures would die first.

“It’s not like everything is fine until 2300, and then all of a sudden hell breaks loose. It’s more like a gradual, kind of accumulated loss of species over time that by 2300,” Deutsch said.

If greenhouse gas emissions continue to accelerate, ocean extinctions from climate warming would rival the “Big Five” mass extinctions in Earth's past.

If greenhouse gas emissions continue to accelerate, ocean extinctions from climate warming would rival the “Big Five” mass extinctions in Earth’s past.
Drawing: Penn and C. Deutsch with illustrations by Yesenia Román

Malin Pinsky, an associate professor of ecology at Rutgers University, wrote an accompanying perspective article on the research. He pointed out that a worst-case scenario is horrible for both people and marine life.

“Seafood’s an important part of their diet and provides jobs for many people… it’s a really important part of our economies, our quality of life,” he told Earther. “[The ocean] provides enormous amounts of money to our national economy, and the global economy keeps people employed.”

That doesn’t mean there isn’t hope. The mass extinction event can be stopped (along with other looming climate disasters) if our systems are decarbonized. “Reversing greenhouse gas emissions trends would diminish extinction risks by more than 70%, preserving marine biodiversity accumulated over the past ~50 million years of evolutionary history,” researchers wrote in the paper.

“The 70% refers to how much of the biodiversity loss could be avoided,” Deutsch said. By limiting warming from this point on, there would still be species loss, “but it’s relatively small and wouldn’t be described as a mass extinction.”

How do we do that exactly? According to Pinsky, the answer is to actually follow through with the Paris Agreement by lowering emissions, stopping global temperatures from rising more than 1.5 degrees Celsius. “At least for me, I’ve got kids. I want them to grow up in a world full of wildlife and seafood and plenty of beautiful ecosystems like coral reefs and rainforests,” he said.

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