There are a few ways people might potentially store more carbon dioxide in the ocean without increasing its acidity to help restore our climate. Our Technical Thursday series on how oceans capture and store carbon covered the basic principles of how the ocean functions to help remove and store carbon dioxide. Here, learn some new ideas for how it might be possible to capture and store more.
- Take advantage of the natural process of photosynthesis to capture and store more carbon dioxide. Photosynthesis is how green plants use sunlight to synthesize food from carbon dioxide and water. Restoring coastal blue carbon ecosystems, including salt marshes, mangroves and seagrasses, can increase the amount of carbon stored in coastal sediments. Cultivating seaweed on a large scale could also help. The seaweed could also be used as feed for livestock, helping to reduce the methane emissions of cattle.
- Iron fertilization is a controversial idea that involves adding trace amounts of iron to certain parts of the ocean, spurring phytoplankton growth. (Phytoplankton are microscopic marine algae). The phytoplankton would take in atmospheric carbon dioxide as they grow, with a portion expected to eventually sink to the ocean floor, resulting in permanent storage of that carbon in ocean sediments.
- Chemical approaches involve adding different types of minerals to the ocean to react with dissolved carbon dioxide. This could lower the concentration of dissolved carbon dioxide relative to the air, allowing the ocean to absorb more carbon dioxide from the air at the ocean-air boundary.
- Finally, another approach involves running electric currents through seawater. For example, one team of scientists have developed a machine that pulls seawater through a mesh that gives the water an electric charge. This triggers chemical reactions that combine dissolved carbon dioxide with calcium and magnesium in the water, creating limestone and magnesite. These materials—essentially ground-up seashells—can either be disposed of on land or released back into the ocean.
World Resources Institute, Leveraging the Ocean’s Carbon Removal Potential
Fast Company, “This carbon-capture tech removes CO2 from the ocean by making seashells”