for National Geographic News
Imagine an ocean full of giant pipes that pump up cold, nutrient-rich water from deep below, encouraging surface algae to bloom and suck carbon dioxide from the atmosphere.
That's the controversial new vision of James Lovelock, the independent British scientist best known for proposing the Gaia hypothesis, and Chris Rapley, a space physicist and director of London's Science Museum.
The pair claims that such climate engineering solutions may be the only way to hold global warming at bay given its current progress. (See a global warming interactive.)
"Global warming appears to be an irreversible process, and if we don't do anything then the world will just heat up to a stable, hot state," Lovelock said. "The stakes are now so high that we have to act."
But other experts are skeptical, pointing out that the scheme could release more carbon than it absorbs while putting fragile marine life in danger. (Related: "Plan to Dump Iron in Ocean as Climate Fix Attracts Debate" [July 25, 2007].)
Lovelock and Rapley say their proposal is the oceanic equivalent of planting trees. But with more than two-thirds of Earth covered in ocean, the plan could be applied on a much grander scale.
The pair's preliminary calculations indicate that an array of between 10,000 and 100,000 pipes would be required, with each pipe around 33 feet (10 meters) wide and 330 feet (100 meters) long.
Wave energy would make the pipes bob up and down. One-way valves inside the pipes would then force water to circulate, bringing nutrient-rich water up to the surface.
"This would stimulate algal growth and help to draw down carbon dioxide," Lovelock said.
A further benefit from the increased algal blooms is that they would produce dimethyl sulfide, a chemical that helps sunlight-reflecting clouds to form, the scientists say.
The idea is outlined in this week's issue of the journal Nature.
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