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How air imperils the sea

Rising levels of carbon dioxide make oceans more acidic, putting shellfish, corals, and more at risk.

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Scientists once thought that holding atmospheric CO2 level to 450 ppm was sufficient to ward off the worst effects of global warming. But a number of scientists and environment groups now say new research indicates that 350 ppm is the highest safe level. Even 450 ppm had been seen an ambitious target. The global CO2 level, now at 385 ppm, is growing by about 2 ppm each year.

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The ability of CO2 in the air to increase the acidity of ocean water is well-established science, “not controversial,” says Victoria Fabry, a marine biologist and visiting researcher at Scripps Institution of Oceanography at the University of California, San Diego. But the study of the effects of acidification is a relatively young field, developing “in the last decade or so,” Dr. Fabry says.

The next task for researchers is to gain a big-picture view of what is happening across a variety of species and to study how acidification might act in concert with ocean warming and other stresses on marine life, she says.

Suggestions for protecting coral reefs include treating water near reefs to keep the pH level elevated, restricting human visitors, even putting shade cloths over reefs to lower the water temperature. Such solutions would likely be practical only in very limited areas.

“It’s difficult to see how they could be scaled up to have a global impact,” she says.

A controversial remedy

Russ George calls CO2 a “chemical shock treatment” to the world’s oceans. “The tragedy is that people think the oceans might be OK if we just leave them alone,” says the entrepreneur, a former environmental project manager for the government of Canada.

It’s too late to rely on reducing the level of CO2 in the atmosphere to prevent ocean acidification, Mr. George says. Because current CO2 levels will take a century or more to fall, he says, “the amount of CO2 already emitted is a lethal dose.”

His solution is to dump iron dust into the ocean. Iron encourages the growth of algae blooms, which in turn absorb CO2. For every ton of iron added to the ocean, 100,000 tons of carbon are captured and held by algae, George says. (Algal blooms also deplete oxygen in the water, creating other problems.)

George created Planktos Corp., bought a ship, and set about conducting experiments in dumping iron dust, first near the Galapagos Islands and later near the Canary Islands. If it proved effective, his plan was to scale up the process and sell carbon credits to companies looking to offset their CO2 emissions.

Protests from environmental groups scrapped his plans. They saw it as toxic ocean dumping, he says. “It scared the living daylights out of our investors ... and we went broke.”

Iron dumping “is fairly controversial,” says marine biologist Victoria Fabry, a visiting researcher at Scripps Institution of Oceanography at the University of California, San Diego. “What you’re doing there is producing more organic matter,” she says. If the algae sink and decompose, the CO2 would be trapped. “You would hope it would sink as far as possible, so that it would be removed from the atmosphere for as long as possible,” she says.

Iron dumping also “seems to have a lot of major questions associated with the side effects and the actual risks that could be created in the ocean ecosystem as a result,” says Jacqueline Savitz, a senior scientist at Oceana, an oceans advocacy group. “They haven’t really been fully answered.”

George has reconstituted his company as Planktos Science and is looking for new investors. He says he’s hopeful he’ll get a chance to conduct his experiment. “We’re undeterred,” he says. “But it’s not going to happen unless people help.”