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Oceans, those vast expanses that cover nearly three-quarters of the planet and hold almost all its water, are in serious trouble. They’re becoming increasingly acidic, putting at risk creatures from small mollusks and gregarious black oystercatchers to hulking walruses. Today nations across the world are joining forces to tackle this devastating problem. 

The United States, Italy, France, and Spain are among those involved in the Ocean Acidification International Coordination Center. Member countries are aiming to better understand how species are being affected, and then make recommendations to adapt natural resource management accordingly. “Through this platform, all the actors in the field—scientists, decision makers, policy makers—could get the information they need,” says Michel Warnau, head of the International Atomic Energy Agency’s Radioecology Laboratory. The center helped organize a November workshop on ocean acidification’s impact on fisheries and aquaculture.

Our emissions are largely to blame for the growing acidity, which could push the oceans’ chemical balance to levels not seen for 20 million years, since the Miocene. Oceans are natural carbon sinks, absorbing the gas we’ve been pumping into the atmosphere. But all of that added carbon is changing seawater chemistry. “For a long time it was thought the oceans were capable of buffering that change,” says Libby Jewett, director of NOAA’s year-old Ocean Acidification Program and a coalition member. “The oceans are no longer able to buffer.” 

That likely spells bad news for animals all the way up the marine food web, Warnau says. Scientists expect that coral reefs and shell-forming organisms like oysters and mussels will be hardest hit because the acidic environs dissolve the calcium carbonate they use to build their hard exoskeletons. Short-term research also shows that at least one reef species, the cinnamon clownfish, can survive increased CO2 levels as long as multiple generations are exposed to higher acidification. “Will the impacts be the same in the longer term? Do the species  have some capacity to cope over time?” asks Philip L. Munday, a fish ecologist at Australia’s James Cook University. “That’s going to be the most critical question in my mind.”

Time is of the essence. If we continue at our current emissions rates, by century’s end the oceans may be 150 percent more acidic than they are today. “It’s early,” Munday says. “We’re just starting to understand the issues. Turns out, it’s much more complicated than we actually thought.” With such an enormous global problem, a global collaboration bent on churning out solutions may be our best, and perhaps only, chance to tilt the balance in favor of our oceans.

This article originally ran in the November-December issue as, "Acid Indigestion."