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Riled Up is a journal of science, the environment, exploration, new technology, and related commentary.  Contributors include scientists, explorers, engineers, and others who provide perspectives and context not typically offered in general news circulation.  For interested readers, additional resources are included.

The Conservation Alliance

Assessing Ocean CO2 Removal

Assessing Ocean CO2 Removal

Marine macro-algae, California brown kelp (credit: NAS)

 

The National Academy of Sciences (NAS) has evaluated potential technologies for atmospheric carbon dioxide (CO2) to be efficiently and safely removed using targeted, ocean geo-engineering.

According to the Academy, the US needs to  understand the benefits and risks of removing or sequestering CO2 by applying ocean-based interventions like cultivating seaweed or manipulating seawater nutrients. The Washtington DC based organization concluded the nation should undertake a targeted initiative to learn how several scientific and engineering methods could be used to help reduce impacts from climate change. Their reasoning accepts that current CO2 levels greatly exceed the ability of nature to now remove the gas and that reducing emissions alone may not be enough to reduce the impacts already occurring.

The NAS recommends a 10-year research program to evaluate the challenges of ocean-based CO2 removal. The effort should begin now and examine the trade-offs between ocean-based strategies with other negative emissions technologies like electric vehicles or renewable energy. The research proposed included evaluation of six specific efforts and made recommendations on:  

  • Nutrient fertilization: adding 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 transports carbon dioxide to the deep ocean 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 take up CO2;
  • Electrochemical processes: passing an electric current through ocean water can 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 the technologies was evaluated for its potential success, cost, and negative effects. The complete NAS report is available here.

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