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Coral Reefs Are Fighting Back Against Global Warming

When they get stressed by the heat, coral make their own shade by releasing a chemical that helps clouds form

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Photo: Tom Nugent

Coral reefs are on the receiving end of the battering ram that is anthropogenic climate change. With their vibrant colors and exotic fish, they’re the poster child of ocean degradation, and they get a lot of attention because they’re on the front lines—their habitats are among the most sensitive to the warming waters. But new research, led by Jean-Baptiste Raina, has found that coral are fighting back: coral can release a chemical, dimethylsulphoniopropionate (DMSP), that helps them engineer their environment and stave off global warming.

When DMSP is released to the environment, bacteria living in the water convert it into a different related gas, dimethylsulphide (DMS). DMS, the scientists say, can control the local climate by spurring clouds to form. More DMS means more clouds, and more clouds means cooler ocean waters for the coral to live in.

The discovery marks the first time that an animal has been found to produce DMSP. Previously, scientists thought it was the algae living in the coral that made the gas, but the new research found that the coral itself can churn it out. And, perhaps more importantly, corals’ DMSP production goes up when the coral gets stressed.

The idea of “DMS-as-climate-regulator,” says Hannah Waters for her blog, Culturing Science, “rose to fame when it starred in one infamous Earth-as-organism idea—the Gaia hypothesis—just a few decades ago.”

The Gaia hypothesis, pitched by James Lovelock, is largely bunk, but dimethylsulphide’s effect on the temperature is not. “In order for clouds to form, water has to transition from a gas to liquid—and to do that, it needs a small particle in the air to adhere onto, known as a cloud condensation nucleus. Sulfur aerosols, which are easily formed from DMS, do the trick,” says Waters.

The discovery that corals can pump out dimethylsulponiopropionate, and hence DMS, say the researchers in their study, adds another reason to worry about their decline. Raina et al:

Considering declining trends in coral cover and predicted increases in coral mortality worldwide caused by anthropogenic stressors, the associated decline in sulphur aerosol production from coral reefs may further destabilize local climate regulation and accelerate degradation of this globally important and diverse ecosystem.

More from Smithsonian.com:

What Does “Unprecedented Climate” Mean?
Zombie Corals Can Come Back From the Dead

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About Colin Schultz
Colin Schultz

Colin Schultz is a freelance science writer and editor based in Toronto, Canada. He blogs for Smart News and contributes to the American Geophysical Union. He has a B.Sc. in physical science and philosophy, and a M.A. in journalism.

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