Woods Hole tests ocean alkalinization in Gulf of Maine

Researchers from the Woods Hole Oceanographic Institution, with U.S. government authorization, released roughly 62,000 liters (about 16,500 gallons) of diluted sodium hydroxide into the Gulf of Maine in August 2025. A rhodamine dye was added, turning the water a bright pink that was visible to drones and satellites. The experiment aimed to raise seawater pH, convert dissolved CO₂ into stable bicarbonate, and assess whether the ocean can be made a more effective carbon sink. Preliminary monitoring showed pH values rising from about 7.95 to 8.3 in targeted zones and reported no detectable negative effects on local marine fauna. The test represents one of the first large‑scale field trials of ocean alkalinization as a geo‑engineering climate‑mitigation strategy.