USC researcher experiments with changing ocean chemistry

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Molly Peterson/KPCC

In his lab, USC's Dave Hutchins is simulating possible future atmospheres and temperatures for the Earth. He says he's trying to figure out how tiny organisms that form the base of the food web will react to a more carbon-intense ocean.

Burning fossil fuels doesn't just put more carbon into the atmosphere and help warm the climate. It's also changing the chemistry of sea water. KPCC's Molly Peterson visits a University of Southern California researcher who studies the consequences of a more corrosive ocean.

Tailpipes and refineries and smokestacks as far as the eye can see in Los Angeles symbolize the way people change the planet's climate. They remind Dave Hutchins that the ocean's changing too.

Hutchins teaches marine biology at USC. He says about a third of all the carbon, or CO2, that people have pushed into earth’s atmosphere ends up in sea water – "which is a good thing for us because if the ocean hadn’t taken up that CO2 the greenhouse effect would be far more advanced than it is." He smiles.

Hutchins says that carbon is probably not so good for the ocean. "The more carbon dioxide that enters the ocean the more acidic the ocean gets."

On the pH scale, smaller numbers represent more acidity. The Monterey Bay Aquarium Research Institute estimates we've pumped 500 million tons of carbon into the world's oceans.

Dave Hutchins at USC says that carbon has already lowered the pH value for sea water. "By the end of this century we are going to have increased the amount of acid in the ocean by maybe 200 percent over natural pre-industrial levels," he says. "So we are driving the chemistry of the ocean into new territory – into areas that it has never seen."

Hutchins is one of dozens of scientists who study the ripples of that new chemistry into the marine ecosystem.

Now for an aside. I make bubbly water at home with a soda machine, and to do that, I pump carbon dioxide. That is a very unscientific, informal, high-speed version of what's happened since people started burning fossil fuels, and that makes water more acidic.

One big consequence of acid in the ocean is that it reacts with other chemicals and stunts coral's growth, and makes it harder for mollusks and clams to grow shells. Just for fun, I'm carbonating some sea water, and dropping shells into the jars. I'll post pictures of the results here.

Poking stuff to see how it reacts is one of Dave Hutchins' favorite things to do. "It’s a manipulative experiment, we call it. You change something in a controllable way and that will give you a lot of insight into how the unperturbed system works," he says.

In his lab at USC, Dave Hutchins shows me containers of water – labeled with numbers that represent years. He carefully pumps measured mixes of air into those containers – to imitate a more carbon-intense atmosphere in the future – and he monitors tiny organisms called phytoplankton to see how they do.

His lab is a more controlled environment than the open ocean. "Everything is changing for them out there right now. Not just acidity, or temperature. Not just the pH. But everything that supplies them," Hutchins says, getting more animated. "Nutrients, light, other organisms they have to compete with are shifting around, and it's important to understand how they're going to react."

Hutchins says a more corrosive ocean chemistry could shift the entire food web. At the bottom of that web, drifting plant-like organisms may feed well off chemicals that become more common.

Further up the food chain, Hutchins says, sea snails and other animals with shells may struggle – and that could spell trouble for the Pacific salmon and larger fish that eat them. He says ocean acidification is like several experiments at once, out of control, overlapping and nowhere near over.

"That CO2 is coming from us, it’s coming from China, India, deforestation in Brazil and Southeast Asia," he says. "And it’s entering the global ocean, but the impacts of that are going to make themselves felt on a local basis."

Dave Hutchins says it's alarming that he and other scientists find it so hard to predict how chemistry will change the ocean in the next hundred years. But he adds that unpredictability also gives him good reason to work harder at finding out.

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