Geoengineering Via Ocean Alkalinity Enhancement by Adding Sodium Hydroxide: Experiment Offshore Maine Began in August 2025

     In August 2025, 65,000 liters (about 17,171 gallons) of sodium hydroxide tagged with a red dye were released into the Gulf of Maine in a geoengineering experiment. The goal of this Ocean Alkalinity Enhancement (OAE) experiment is to raise the local ocean pH to counteract growing acidity. The sodium hydroxide was added over a four-day period off the coast of Boston. A secondary effect of the sodium hydroxide release is to increase ocean uptake of CO2.

     An article in the Daily Mail explains the experiment:

“The LOC–NESS (Locking Ocean Carbon in the Northeast Shelf and Slope) project is the first large–scale experiment to test the impact of OAE in an open water setting.”

“With approval from the US Environmental Protection Agency and engagement with local fishers, scientists from the Woods Hole Oceanographic Institution poured alkaline chemicals into the ocean 50 miles (80 km) off the Massachusetts coast.”

“They then used cutting–edge technology, including autonomous gliders, long–range autonomous underwater vehicles and shipboard sensors to track the spreading chemicals.”

“Over the next few days, the scientists measured 10 tonnes of carbon entering the water as the pH increased from 7.95 to 8.3 – matching pre–industrial levels.”

     Over the next year, the sodium hydroxide released could lead to an uptake of as much as 50 tons of CO2 in the best-case scenario.

     The researchers note that this experiment involves tracking the results of the sodium hydroxide release and setting the stage for future experiments, as well as developing a basis for engineering, tracking, and monitoring experimental results. In this experiment, it was found that sodium hydroxide had no negative impacts on plankton, fish, and lobster larvae. However, the effects on adult fish were not assessed. Knowing these effects is important since this oceanic region is known for its fishing industry.

“Rachel Davitt, a PhD student from Rutgers University who helped lead the ecological assessment, says: 'Based on the biological and ecological impact data that we have collected and analysed so far, there was no significant impact of the LOC–NESS field trial on the biological community using the metrics we measured.”

     Critics say the biggest unknown of the experiment is the effects on marine wildlife. They also say that OAE does not address the root of the problem, which is the amount of CO2 being emitted to the atmosphere, describing it as a short-term fix.

     According to Gareth Cunningham, Director of Conservation and Policy at the Marine Conservation Society:

“Restoring natural habitats like seagrass and shellfish reefs offers a more sustainable solution by helping buffer acidification while improving water quality, protecting coastlines and supporting marine life – which is exactly what we're doing through our Atlantic Coast Programme here in the UK.”

     A few of the concerns about excessive ocean alkalinity enhancement include effects on species growth, metabolism, and biodiversity, and the release of trace metals.

     Below are common methods and proposals for geoengineering, their effects, and drawbacks.

 

  

  

References:

 

Controversial geoengineering project sees scientists pump 65,000 litres of chemicals into the ocean to stop global warming. Wiliam Hunter. Daily Mail. March 10, 2026. Controversial geoengineering project sees scientists pump 65,000 litres of chemicals into the ocean to stop global warming | Daily Mail Online