A report released on Wednesday by the National Academies of Sciences, Engineering, and Medicine looks towards the planet’s oceans to combat climate change. The nearly 300-page document presents a variety of potential solutions ranging from seaweed farming to administering electric shocks to reduce an ocean’s acidity. Estimated research costs range from allocating $25 million to investigate artificial wave creation to spending $350 million to research electrochemical solutions.
The world’s oceans function as a massive carbon sink already, capturing about a quarter of all man-made emissions. Moving from land to sea certainly makes sense in this context. There are six solutions presented in the report along with an estimate of their risks and effectiveness. They include adding minerals to make the ocean less acidic, adding nutrients to stimulate plankton photosynthesis, and a series of plans meant to restore the ocean’s ecosystem. Scientists are doubtful that ecosystem recovery would yield meaningful benefits, however.
When reached by the Associated Press, Breakthrough Institute climate scientist Zeke Hausfather said he was the most confident in electrochemical solutions to fight ocean acidity. “[It has] the highest potential for long-term carbon removal at a scale large enough to make a meaningful impact,” Hausfather said. Though our oceans can absorb massive amounts of greenhouse gasses, it comes at a cost: All that carbon dioxide turns into carbonic acid, which threatens marine life. Neutralizing that acidity could be a game-changer. Hausfather is less certain about ocean fertilization, which would include adding nutrients like phosphorous to stimulate photosynthesis in plankton.
The plankton would absorb carbon dioxide then sink to the bottom of the ocean. Carbon degrading would eventually take place, though the timetable on that varies depending on where in the ocean the plankton ultimately land and which oceans are used. This method could come at risk to fisheries and biodiversity, as could many of the methods cited in the report. Researchers are honest in their assessments and consider not just the potential environmental risks but the many legal and regulatory hurdles that could stymie geoengineering efforts.
All techniques have multiple hurdles to overcome, ranging from feasibility to regulatory challenges. Dumping tons of iron in the ocean, for example, could have unintended consequences for marine life and fisheries, while zapping carbon dioxide out of ocean water would require large amounts of energy. These are all bleeding-edge areas of research with major outstanding questions. Among them is how permanent these approaches are. To be successful, sequestered carbon will likely need to end up in the deep sea. If it stays in the first 3,280 feet (1,000 meters) of the ocean, it will likely be put back in the atmosphere at some point, negating the benefits of sucking it up in the first place. These and other high-stakes research questions would form the backbone of any carbon dioxide removal study program.
Some environmental laws at the national and international level cover geoengineering the seas. The report notes the Paris Agreement gives implicit support to carbon dioxide removal with several mentions of carbon sinks. But other treaties, such as the Convention on Biological Diversity, have put a “de facto moratorium” on geoengineering oceans. The treaty—adopted by all United Nations members but curiously not ratified by the United States—serves as critical guidance to protect the planet. It was drafted in 1993 and, in 2010, its signatories agreed to halt geoengineering based on the lack of scientific data available, though research can still be done. That means the world has a long way to go when it comes to plumbing the depths of the seas for climate solutions.