American scientific leaders say that the ocean can be used to remove carbon from the air
The United States should launch a major research project to study how to artificially use the ocean to remove carbon dioxide from the air, saying A new report From the National Academy of Sciences, Academy of Engineering, and School of Medicine.
Scientists are increasingly inclined to believe that reducing carbon emissions may not stabilize the climate and may require technologies that actively remove carbon from the air. New report established in 2019 National Academy of Sciences Research The study found that in order to achieve the internationally agreed climate goals, by 2050, countries around the world will need to remove approximately 10 billion tons of carbon dioxide from the air each year—almost a quarter of current annual emissions—in addition to reducing emissions. The authors say that although some land-based strategies, such as storing carbon in agricultural soils or changing forest management, may now be ready for deployment, little is known about the risks, benefits, and trade-offs of ocean-based strategies. Some forward-looking methods may include large-scale cultivation of seaweed, manipulation of seawater nutrients, and even electricity in the water.
The report recommends a $125 million research program to better understand the technical challenges and potential economic and social impacts. It said that this research should start now and continue in the next 10 years.
Coast of Barbados. (Kevin Krajic/Earth Institute)
“All land-based methods have limitations, so it is important to assess the possibility of using the ocean as well,” said the co-author Romani Weber, Senior Researcher and Associate Researcher, Columbia University Sabine Center for Climate Change Law“Importantly, the report not only identifies key scientific questions that need to be answered, but also social, legal, regulatory, and policy issues.”
“Marine CO2 removal strategies have been discussed by scientists, NGOs, and entrepreneurs as potential climate response strategies,” said Scott Donney, chairman of the committee and professor of environmental sciences at the University of Virginia. “Currently, society and policy makers do not have the information needed to assess impact and weigh.”
The report explores six basic methods:
Nutritional fertilization This will involve adding nutrients such as phosphorus or nitrogen to the surface of the ocean to increase the photosynthesis of phytoplankton. Some phytoplankton will sink after death, so this will increase the transfer of carbon to the deep sea, where it can stay for a century or more. The report stated that this method will be effective and scalable, with moderate environmental risks, and in addition to environmental monitoring costs, its expansion costs are low, with moderate to high levels of confidence. The report estimates that US$290 million will be needed for research, including field experiments and tracking the resulting carbon sequestration.
Seaweed cultivation According to the report, large-scale seaweed farming, which transports carbon to the deep sea or sediments, has medium efficacy and medium-to-high durability in removing carbon dioxide from the atmosphere. But there will be medium to high environmental risks. The report estimates that US$130 million is needed for research to understand the technology for efficient large-scale farming and harvesting, the long-term fate of seaweed biomass, and environmental impact.
Ecosystem restoration The protection and restoration of coastal ecosystems and the subsequent restoration of fish, whales and other marine wildlife can help capture and sequester carbon. The authors say that it has the lowest environmental risk and high synergistic benefits among the assessment methods. The report stated that it may have low to medium efficacy. It estimates that $220 million is spent on research, including research on the impact on macroalgae, marine animals, and marine protected areas.
Increased ocean alkalinity This method chemically alters seawater to increase its alkalinity to enhance the reaction of absorbing atmospheric CO2. According to the report, people have high confidence in its efficacy. Increased ocean alkalinity brings moderate environmental risks and moderate to high scale expansion costs. The report estimates that between 125 million and 200 million US dollars will be spent on research, including field and laboratory experiments, to explore the impact on marine life.
Electrochemical process Passing electricity through the water can increase the acidity of seawater to release carbon dioxide, or increase its alkalinity to enhance its ability to retain carbon dioxide. Have high confidence in its efficacy and moderate to high confidence in its scalability. However, this method has the highest scale-up cost among all evaluation methods and has a medium to high environmental risk. The report estimates that US$350 million will be spent on research, including for demonstration projects, as well as improvement materials needed for development and evaluation.
Artificial upflow and downflow Upwelling moves the cooler, more nutritious and carbon dioxide-rich deep water to the surface, stimulating the growth of phytoplankton. Downflow transfers surface water and carbon to the deep ocean. The report stated that people’s confidence in the effectiveness and scalability of these methods is low. They bring moderate to high environmental risks, as well as the high costs and challenges of carbon accounting. The report estimates that US$25 million is required for research, such as technical preparations and limited and controlled marine experiments.
The research is supported by Marine Carbon Dioxide Removal and Storage Research Strategy Committee, Sponsored by the Climate Engineering Foundation.
Adapted from press releases from the National Academy of Sciences, Academy of Engineering, and School of Medicine.
