Why do some scientists want to scatter tubes throughout the open ocean?

Some scientists think ocean pipes could bring down carbon dioxide levels by stimulating upwelling.
Some scientists think ocean pipes could bring down carbon dioxide levels by stimulating upwelling.
HSW 2008

­It seems like global warming gets worse by the minute as every day brings news of ice shelves melting, coral reefs dying and sea levels rising. Meanwhile, the global population is at 6.7 billion and growing, and we continue to consume with abandon [source: U.S. Census Bureau]. Despite environmentalists' best efforts, it sometimes looks as though we're not going to able to save ourselves fast enough from the looming catastrophe that is climate change.

But if we can't do it ourselves, can we get the Earth to do it for us?

That's the basic premise behind one of the latest ideas to lower atmospheric carbon dioxide. Scientists suggest that by placing giant tubes in the oceans, we can encourage the natural process of upwelling, whereby cold, nutrient-rich water rises to the ocean surface and stimulates the growth of phytoplankton, or algae. The algae in turn consume large amounts of carbon dioxide for photosynthesis, lowering atmospheric levels of the greenhouse gas. Dimethyl sulfide produced in the process could also encourage the formation of clouds to reflect the sun's rays.

The vertical tubes wouldn't require any outside energy input, and would instead rely on the natural energy of wave motion to force water up their 656-foot (200-meter) length. A flap or valve at the bottom of each tube would keep the flow of water one-way. The idea is to place the tubes, which would probably be between 10 and 33 feet (3 and 10 meters) wide, approximately 1.2 miles (2 kilometers) apart and secure them using underwater tethers and surface buoys.

­Initial estimates indicate that with 10-foot (3-meter) waves, the 10-foot diameter tubes could cool an entire 1.5-square-mile (4-square-km) area that is 98 feet (30 meters) deep by one half degree (a 5 percent decrease in temperature) in one month. The uppermost ocean layer might see reductions of a few degrees more.

Furthermore, the nutrient-rich water would increase phytoplankton by more than 26,455 pounds (12,000 kg) leading to a drawdown of 1,711 pounds (776 kg) of carbon and a 265-pound (120-kg) increase in the amount of fish [source: Atmocean].

Beyond the effects on global temperature, the cooler ocean surface could also help to alleviate hurricane intensity. Current models show that since hurricane winds draw much of their energy from warm ocean surface waters, the cooler waters created by the ocean pipes could lower those winds by up to 15 percent, resulting in a 40 percent decrease in storm damages. One company's storm track analysis lead it to hypothesize that if the tubes had been in place 10 years ago, they could have reduced the impact of 84 percent of the hurricanes that hit the U.S. [source: Atmocean].

Right now, the ocean pipes are still in their initial testing phases, but the preliminary studies do show promise. So why are some people far from convinced? Find out why on the next page.