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The winner in climate change? It might be way down the food chain

Geobiologist Frank Corsetti looks to the past to postulate our climate future

Sea sponges
Their dependence on silica likely gave sea sponges an advantage in an age of climate change between the Triassic and Jurassic periods. (Photo/NOAA Ocean Explorer)

Global temperatures climb, acid levels in the Earth’s oceans spike and sea levels rise.

Next come the dinosaurs.

No, we’re not talking about today’s climate change phenomena. Think back — way back — to what’s called Triassic-Jurassic extinction event, some 201 million years ago. The tectonic forces that ripped Pangaea into continents caused a massive lava flow, spewing an enormous amount of carbon dioxide into the air. It marked one of the greatest swaths of species loss the Earth has ever seen.

Geobiologist Frank Corsetti of the USC Dornsife College of Letters, Arts and Sciences believes the event can help understand modern-day climate change. He’s studying layers of stone from long ago to predict global warming’s effects on our future Earth.

“These layers of rocks, they carry a story. It’s like a time machine,” he said.

It was no Jurassic Park for coral

Presenting at the recent annual meeting of the American Association for the Advancement of Science, the largest general science gathering in the world, Corsetti talked about the effects of the lava flow, known as the Central Atlantic magmatic province. While the exact causes of the extinction are still under debate, scientists estimate that more than three quarters of the world’s species disappeared.

Particularly hard hit: Coral reefs and animals that use calcium carbonate to create their shells. The ocean’s increasing acid dissolved those carapaces, just as coral reefs are declining today.

“Sponges Clean Up in the Early Jurassic” could be the headline for that era, laughs Corsetti. He’s found evidence that sea sponges with silica-based shells flourished during this time. Because weathering of the Earth’s crust pushed silicates into the seas, these sea sponges had plenty of silica in their environment to draw from.

“If you’re a sponge, you look back at the T-J boundary and say that was the best time in Earth’s history,” Corsetti said.

Think small — no, smaller

Gradually, the amount of carbon dioxide in the environment decreased, possibly consumed by the silicate weathering process.

So in an era of rising carbon dioxide levels and increasing ocean acidification today, are we poised for another sponge takeover? Corsetti doesn’t think so. Instead he points to a tinier life form — one far smaller than a sponge, and certainly much smaller than a dinosaur.

His money might be on single-celled algae called diatoms: phytoplankton that use silica to build their shells. They can form colonies and live in water or damp soils.

“Perhaps,” he said, “diatoms are the next ‘winner’ in this situation.”

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The winner in climate change? It might be way down the food chain

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