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Posted on 11/22/2001 1:24:02 PM PST by AdrianZ

November 20, 2001

Plan Calls for Using Oceans to Soak Up CO2; Critics Cite Perils

By KENNETH CHANG

n the continuing debate over global warming and how to fight it, some scientists and entrepreneurs advocate using the oceans as a sponge to absorb carbon dioxide from the air.

Others are saying not so fast. They argue that widespread ocean dumping of carbon dioxide could unbalance the aquatic environment.

Carbon dioxide is one of the "greenhouse gases" that trap heat. Most scientists believe that carbon dioxide from the burning of fossil fuels is a large factor in the warming temperatures of the last century and that capping those emissions is essential for limiting future warming.

Much of the extra carbon dioxide already dissolves into the oceans, where it has no effect on temperatures. Two schemes seek to augment that natural process.

One is to catch carbon dioxide from the smokestacks of power plants before it enters the atmosphere, squeeze it into liquid form and then pump it into the deep oceans.

The other is to fertilize oceans to produce blooms of algae that pull carbon dioxide out of the air. Proponents believe that as the bloom dies off, much of the algae will sink to the ocean floor, and the carbon dioxide — transformed into plant material — would be safely subtracted from the warming equation. A private company called GreenSea Venture hopes to make a business of this.

But some scientists argue that engineering nature to avoid environmental damage inevitably causes other, perhaps greater damage.

Writing in the Oct. 12 issue of Science, Dr. Brad A. Seibel of the Monterey Bay Aquarium Research Institute in Moss Landing, Calif., and Dr. Patrick J. Walsh of the University of Miami caution that carbon dioxide could harm deep-sea creatures.

Enshrouded in perpetual cold and dark, these creatures like the anglerfish live in slow motion, their metabolisms consuming energy at as little as one-thousandth the rate of those closer to the surface. The slow metabolism makes them particularly sensitive to chemical changes in their environment, the authors say.

When carbon dioxide dissolves, it turns into carbonic acid, making the water more acidic. But biologists have observed that a change of 0.3 in the pH level in the blood of some deep sea creatures can halve the amount of oxygen. "It may not kill them," Dr. Seibel said, "but they may not be able to swim as actively as they could be before. It'd be like they were out of breath."

Damage to deep-ocean ecosystems could eventually alter the mix of nutrients and chemicals that well up from the depths. "It's still not known what the links between the deep ocean and the shallow ocean are," Dr. Seibel said. "If you damage one, you hurt the other potentially."

A small-scale experiment to pump about 40 tons of liquid carbon dioxide into the waters off Hawaii has run into stiff opposition from some environmentalists and has not received final approval.

Carbon dioxide does kill, as researchers demonstrated in even smaller-scale experiments this year in Monterey Bay.

From a small submarine, the scientists, from the Monterey Bay Research Institute, squirted about five gallons of liquid carbon dioxide into each of several small plastic pools at the bottom, 12,000 feet down. They then put cages containing five sea urchins and five sea cucumbers each about a foot and a half from the carbon dioxide pools, wanting to see how they fared compared with others in cages farther away.

When they returned three weeks later, everything in the cages next to the pools was dead. The researchers found that creatures like small crustaceans living in the nearby sediment were also injured or killed. Modifying the experiment, the researchers then placed sea urchins and sea cucumbers 6 and 15 feet away from the carbon dioxide. Those animals survived without visible injury; tissue samples are being examined for cellular damage.

"It seems CO2 injection will have detrimental effects," said Dr. James P. Barry, an associate scientist at the institute involved in the experiment. "That's almost certain. The degree of damage is the question."

These cautionary notes contrast with the views of Dr. Peter G. Brewer, a senior scientist at the research institute, who supervised the bay bottom experiments and has advocated exploring the idea of injecting carbon dioxide in the ocean. Still, he said the data deserved a full airing.

"Just as putting in a sewage outfall or drilling an oil well, there's an environmental question to be asked," Dr. Brewer said, "and people should do it in an objective way."

In a second Science article on Oct. 12, three scientists — Dr. Sallie W. Chisholm of the Massachusetts Institute of Technology, Dr. Paul G. Falkowski of Rutgers University and Dr. John J. Cullen of Dalhousie University in Halifax, Nova Scotia — strongly criticize the idea of fertilizing to counter global warming.

Some parts of the oceans, primarily in the Southern Hemisphere, are full of nutrients, but sparse in sea life because of a lack of iron. Several small experiments have shown that dumping iron into these waters produces large blooms of algae.

Proponents like Dr. Michael Markels, who founded GreenSea Venture, say the proposal simply mimics a natural process, in which iron-rich dust and volcanic ash blow from land to water. "It would be minuscule in comparison to what happens naturally," Dr. Markels said.

But Dr. Chisholm contends that it is difficult to measure how much carbon sinks and that the algae blooms could suck oxygen out of the water, chasing away fish and that a profit motive would lead to reckless overfertilization.

"It's like saying: `What's so bad to adding carbon dioxide to the atmosphere? There's already CO2 in the atmosphere," she said.

The GreenSea approach has not yet received widespread support, with the Department of Energy turning down its grant proposals.

GreenSea's business plan also depends on the selling of "carbon credits" proposed under the Kyoto treaty on global warming. The Bush administration has rejected the Kyoto treaty and has also objected to the concept of carbon credits.

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