For four days last August, a thick slick of maroon bruised the waters of the Gulf of Maine. The scene was the result of 65,000 litres of an alkaline chemical, tagged with a red dye, that had been deliberately pumped by scientists into the ocean. The event was part of a scientific experiment that could advance a technology to combat both global heating and ocean acidification.
Ocean alkalinity enhancement (OAE) acts like natural weathering, but on human – rather than geological – timescales. Adam Subhas, lead oceanographer of the research team, stated that the ocean holds 38,000 billion tonnes of carbon, stored as dissolved bicarbonate, or baking soda. Boosting this natural alkalinity using a chemical antacid should, in theory, encourage the ocean to absorb more carbon.
Over a large surface area, and in combination with sharp emissions reductions, OAE could prevent global temperatures exceeding 2C above preindustrial levels, while locally reducing ocean acidity. Ocean acidity is now higher than at any point in the past million years and poses a dire threat to marine life and fisheries. The experiment was licensed by the US Environmental Protection Agency and overseen by scientists from the Woods Hole Oceanographic Institution.
It took place 50 miles off the coast of Massachusetts in an area commonly fished for cod, haddock and lobster. Over five days at sea, the Loc-ess project used state-of-the-art technology to trace the dispersal of 65,000 litres of sodium hydroxide, an alkaline chemical that was tagged with a red dye, from the release site. 3, which represents a return of ocean alkalinity to preindustrial levels.
The experiment showed no significant harm to creatures including plankton and fish and lobster larvae, but the team did not measure the impact on adult fish or marine mammals. The study has yet to go through peer review. Benjamin Day, senior campaigner on climate and energy justice at Friends of the Earth US, said using chemicals to solve an environmental problem seems reckless.
He added that what we’re seeing is a push to exert more precise control over natural systems, and he is profoundly concerned about the environmental impacts of OEA happening at scale, including the risk of catastrophic unforeseen consequences. Phil Renforth, expert in carbon dioxide removal (CDR) at Heriot-Watt University, noted that we are already experimenting with the climate, in uncontrolled ways, and we really need to think about this in terms of stewardship.