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Climate change is really bad news if you like oysters, scallops and clams

Oysters from a farm at Tangier Island in Tangier, Va. (Photo by Jay Westcott/For The Washington Post)
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When it comes to carbon dioxide emissions, the first environmental problem that comes to mind is climate change. As humans pump more of this greenhouse gas into the air, the Earth gets warmer, and the climate changes in ways that could damage the economy, public health, infrastructure and society.

But along with climate change, these same emissions are causing another pernicious problem in our oceans. Some of the carbon dioxide we emit gets absorbed in sea water, where it turns into carbonic acid in a phenomenon called ocean acidification. As our emissions rise, the oceans will turn more and more acidic, irreparably altering aquatic ecosystems.

Ocean acidification might lack the rhetorical punch that “climate change” and “global warming” have. But as one new study shows, acidification could carry real economic and cultural risks, and we’re only beginning to understand them. Waters off the United States are home to countless oysters, clams, scallops and other shellfish that the seafood industry catches and grows for your dinner. In many of these regions — especially off the East Coast and in the Gulf of Mexico — acidification could harm these creatures enough to deal big blows to local economies and meals, researchers reported Monday in Nature Climate Change.

As humans throw off the delicate water chemistry that shelled seafood species, such as oysters, scallops and clams, are accustomed to, it’ll become harder for them to survive because they’ll struggle to build or maintain their shells.

Still, the oceans are huge, and their conditions vary. So, as is the case with climate change, it’s not easy to forecast, and thus prepare for, acidification’s impacts on the regional level.

That’s why Julia K. Ekstrom of the Natural Resources Defense Council and a number of other researchers from academia and nonprofits decided to study how well U.S. coastal areas are equipped to deal with acidification’s impact on shelled seafood. They divided waters off the United States into 23 “bioregions” — each one being an area with a certain set of characteristics, such as plants, animals and climate.

To assess how vulnerable these regions’ shelled seafood is to acidification, the researchers added the effects of a range of factors. First, they assessed the drivers of acidification and accounted for other effects that can worsen acidity locally. One example is that too many micro-organisms grow when humans pollute the water with nutrient-rich agricultural runoff; all these additional living things, digesting the nutrients and growing, end up releasing carbon dioxide into the water, boosting its acidity.

The researchers also assessed each region’s ability to respond with policy actions to soften acidification’s blow in the event that the seafood industry struggles, as well as each region’s sensitivity to acidification (how much the local economy and culture depend on shellfisheries).

Out of the 23 bioregions, the researchers found that 16 will face dangerous ocean acidification or at least one force that could amplify it. And most of these 16 regions — especially areas in the Atlantic and the Gulf of Mexico — have economies and cultures that depend heavily on shellfisheries. Moreover, many don’t seem to have the right policies, scientific information or economic alternatives to adapt.

A lot of jobs and economic activity are on the line. In the Pacific Northwest alone, acidification is already believed to have cost the seafood industry at least $110 million and affected at least 3,000 jobs. Oysters there are dying in droves as the waters turn more acidic.

The Chesapeake Bay Foundation has also noted that oyster-harvesting industries in Maryland and Virginia have lost $4 billion in the last three decades thanks to pollution and agricultural runoff, which can worsen acidification’s effects.

The more this happens, the more growers and shellfish farmers will go out of business, and the more costly it could someday become to enjoy your favorite seafood dinner. We also still don’t understand the value of other services that oysters, clams, scallops and other shellfish might provide, such as water filtration and coastal protection against storm surge; add in those factors, and even more is at stake.

But some areas, such as the Pacific Northwest and Maine, may not be as hard-hit; they seem to be ahead of the game when it comes to preparing, the researchers suggest. For example, Washington state convened a blue ribbon panel on the issue, and Maine last year created its own commission to study how acidification could impact commercially harvested aquatic species. Interestingly, in these areas, the waters’ acidity is expected to worsen sooner than in the other areas, the researchers say, because relatively chilly waters are better at absorbing carbon dioxide. Maybe the imminence of the problem has helped motivate stakeholders to move quickly to prepare.

To get better-prepared, we still need more science on ocean acidification’s impacts — this study was actually the first to look at acidification’s regional impacts in the United States. Ocean acidification has sort of swum under the public radar, and perhaps that’s a reason that research on acidification, particularly on its impacts, hasn’t gotten much attention. The researchers note that just $270,000 in U.S. funding went toward social science research on acidification in 2011 — just 0.1 percent of all acidification-related spending in that year’s budget.

In sum, there’s yet another burgeoning consequence of society’s carbon habit — and pretty soon, it may affect your seafood habit, too.