Two scientists have come up with a novel way to fight global warming: enormous pipes that would pump cold, nutrient-rich water from the bottom of the ocean to the top, stimulating algae growth and absorbing carbon dioxide. James Lovelock, a reknowned scientist famous for his Gaia hypothesis, and Chris Rapley, director of London's Science Museum, are the authors of the proposal, which was outlined in their letter to the editor in the current issue of Nature. Lovelock and Rapley's vision is of anywhere from 10,000 to 100,000 pipes, 33 feet across and 330 feet long, bobbing up and down in the ocean. Valves inside the pipes would create water circulation, bringing more water to the top of the ocean. The ultimate goal would be that the water circulation would help algae grow, which would then absorb CO2 from the atmosphere. The increased algae would also produce a chemical that fosters formation of sunlight-reflecting clouds. Critics say that the circulating water system might actually introduce more CO2 into the atmosphere: the deep water rising the surface might "exhale" it before absorbing it back. It's also unknown what effects the pipes would have on marine life. Currently, Lovelock and Rapley are working on prototypes and say "we can do a small-scale trial and discover any problems, giving us opportunity to back off if need be."