One approach is to pipe liquid carbon dioxide to depths below about 3,300 feet. At some depths it would remain a liquid and dissolve. If injected very deep, it would end up on the ocean floor as ice-like chunks, the result of a chemical reaction with the water. That would keep the carbon dioxide locked up for an unknown length of time before it dissolved. The potential of the ocean to absorb the gas is immense.
Carbon dioxide changes the pH of seawater, making it more acidic.
Scientists say they don't yet know how the pH change from large-scale disposal would affect ocean life. Next year, an international team of researchers plans to dangle a steel pipeline an inch or two in diameter from a barge off the Kona coast of Hawaii. They want to see what happens when they dribble liquid carbon dioxide into the ocean about a half-mile deep. Scientists will look for an effect on ocean life, but the experiment will probably be too brief and small-scale to cause any disturbance, said Howard Herzog of the Massachusetts Institute of Technology, one of the project's planners. But that would take several centuries to 1,000 years.