Removing Ocean CO2
California brown kelp, a giant marine algae (credit: NAS)
The National Academy of Sciences (NAS) evaluated potential technologies for atmospheric carbon dioxide (CO2) from the oceans can be efficiently and safely removed with targeted geo-engineering.
According to the science academy, the US needs to understand the benefits and risks of removing or sequestering CO2 by applying ocean-based interventions including the cultivation of seaweeds or manipulating seawater nutrients. The Washtington DC based organization concluded the nation should undertake targeted ocean projects to determine how several scientific and engineering methods mighjt be used to reduce CO2 impacts and climate change. Their reasoning accepts that current CO2 levels greatly exceed the ability of nature to remove the heat-trapping gas and that reducing emissions alone may not be enough to reduce impacts already occurring.
The NAS recommends a 10-year research program to evaluate the challenges of ocean CO2 removal. The effort should begin now and examine the trade-offs between ocean-based strategies and compare with other negative emissions technologies such as electric vehicles or renewable energy from wind and solar installations. The proposed research should include six specific efforts and make recommendations about:
- Nutrient fertilization: adding plant nutrients such as phosphorus or nitrogen to increase photosynthesis in ocean phytoplankton, thereby increasing their uptake of CO2;
- Artificial up-welling and down-welling: up-welling moves cooler, more nutrient CO2-rich water to the surface, stimulating phytoplankton to absorb carbon dioxide while down-welling moves surface water and carbon to the deep ocean;
- Seaweed cultivation: large-scale seaweed/kelp farming can utilize carbon dioxide and move it greater depths or into marine sediments;
- Ecosystem restoration: carbon removal and sequestration through restoration of coastal ecosystems and the recovery of marine wildlife;
- Ocean alkalinity enhancement: altering ocean water chemistry to increase its alkalinity to enhance reactions that improve absorption of CO2;
- Electrochemical processes: passing an electric current through ocean water to either increase the acidity of seawater to release CO2 and reduce ocean acidification, or increase the alkalinity of seawater to enhance its ability to retain CO2.
Each of these ocean technologies was evaluated by the Academy for its potential success, the associated costs, and any negative affects. The complete report is available here. WHB