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?

Advertisement

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.

Ocean Pipe Problems: Pipe Busters

Increased ocean acidity can contribute to coral bleaching.
Increased ocean acidity can contribute to coral bleaching.
National Geographic/Getty Images

As nice as it would be to harness the energy of the ocean to do our dirty work for us, sometimes outsourcing can cause bigger problems than the ones it's intended to solve. That could very well be the case with ocean pipes, because while enhancing the ­Earth's natural carbon cycle could theoretically help to reduce levels of the gas, it could also cause several unintended consequences.

One of the main areas of contention is whether the carbon dioxide pulled out of the atmosphere by the algae would actually stay out. The intention, of course, is for the algae to take up the CO2 and carry it to the bottom for good as the organisms die. Another option is for it to sink to the bottom as fecal matter after marine animals consume and digest the carbon-soaked algae. However, there's no guarantee either of those scenarios will happen. Often, the carbon and nutrients consumed by the algae simply go back into the ocean after the organisms die. Alternatively, marine life that eats the algae might simply release the CO2 during respiration.

Advertisement

Another area of uncertainty lies in the simple fact that, as a natural carbon sink, the ocean already stores significant levels of carbon dioxide. This means that when the pipes pump up cold water full of nutrients, they'll also be pumping up carbon dioxide that could initially contribute to global warming. Whether the final tally would be in favor of carbon release or carbon sequestration remains to be seen.

There's also uncertainty about how much CO2 the oceans are capable of holding before they reach the tipping point. While it's true that the ocean was a sink for CO2 before we got involved, tampering with its natural cycle could prove disastrous for marine life. Regardless of the water's temperature, as CO2 levels in the water rise, the ocean's acidity also rises, which endangers its inhabitants. An added consequence of higher carbon dioxide levels in the water is a decrease in the amount of calcium carbonate available for corals and shellfish to incorporate into their shells. Indeed, coral reefs have already suffered significantly due to rising CO2 levels [source: Kloeppel].

Yet another concern with the ocean pipes deals with the algae they're designed to encourage. While the pipes' proponents argue that the ocean surface is currently deprived of algae because warming waters have stalled the natural upwelling process that brings nutrients to the upper layers, detractors point out that if the algae get out of hand, they could contribute to dead zones -- areas where bacteria feed on algae and suck up all the water's oxygen. It doesn't take a scientist to know that low oxygen levels are detrimental to resident marine life.

Whether the benefits of using ocean pipes to pull CO2 ­out of the atmosphere would outweigh negative side effects has yet to be determined. Only time will tell if this global warming solution works or is just another crazy pipe dream.

To learn more about ocean pipes and other creative global warming solutions, try some of the links on the next page.

Related HowStuffWorks Articles

­More Great Link­s

Sources

  • Atmocean. "Atmocean." (July 17, 2008) h­ttp://www.atmocean.com/index.htm
  • Kloeppel, James E. "Regardless of global warming, rising CO2 levels threaten marine life." EurekAlert. Mar. 8, 2007. (July 17, 2008)http://www.eurekalert.org/pub_releases/2007-03/uoia-rog030807.php
  • McCarthy, Michael. "Pipes hung in the sea could help planet to 'heal itself'." The Independent. Sept. 27, 2007. (July 17, 2008)http://www.independent.co.uk/environment/climate-change/pipes-hung-in-the- sea-could-help-planet-to-heal-itself-403651.html
  • Ravillous, Kate. "Giant Ocean Tubes Proposed as Global Warming Fix." National Geographic News. Sept. 26, 2007. (July 17, 2008)http://news.nationalgeographic.com/news/2007/09/070926-warming-solution.html
  • Silverman, Jacob. "Should we be worried about the dead zone in the Gulf of Mexico?" HowStuffWorks. 2008. (July 17, 2008)https://science.howstuffworks.com/dead-zone.htm
  • Thompson, Andrea. "Top Scientist: Stir Up Oceans, Stop Global Warming." Live Science. Sept. 28, 2007. (July 17, 2008)http://www.foxnews.com/story/0,2933,298269,00.html
  • U.S. Census Bureau. "U.S. and World Population Clocks." July 17, 2008. (July 17, 2008)http://www.census.gov/main/www/popclock.html