FFor four days last August, a thick layer of maroon bruised the waters of the Gulf of Maine. The scene, similar to a toxic red tide, was the result of 65,000 liters of an alkaline chemical, marked with a red dye, that scientists had deliberately pumped into the ocean.
As perverse as it may sound, the event was part of a scientific experiment that could advance a technology to combat both global warming and ocean acidification. Ocean Alkalinity Increase (OAE), as this approach is called, acts like natural weathering, but on human, rather than geological, time scales.
“The ocean is already incredibly alkaline. (It contains) 38 billion tons of carbon, stored as dissolved bicarbonate or sodium bicarbonate,” says Adam Subhas, lead oceanographer on the research team that announced the first results of its test at the AGU Ocean Sciences Meeting in Glasgow.
Increasing this natural alkalinity using a chemical antacid should, in theory, encourage the ocean to absorb more carbon. Over a large area, and in combination with strong emissions reductions, OAE could prevent global temperatures from exceeding 2°C above pre-industrial levels, while locally reducing ocean acidity, which is now higher than at any time in the last million years and represents a serious threat to marine life and fisheries.
Licensed by the U.S. Environmental Protection Agency and supervised by scientists at the Woods Hole Oceanographic Institution, the experiment was conducted 50 miles off the coast of Massachusetts in an area where cod, haddock and lobster are commonly fished.
Although small-scale, their study, which has yet to undergo peer review, found promising results. Over five days at sea, the Loc-ess project used cutting-edge technology, including autonomous gliders, long-range autonomous underwater vehicles and onboard sensors to track the dispersal of 65,000 liters of sodium hydroxide, an alkaline chemical marked with a red dye, from the release site.
During that period, they measured up to 10 tons of carbon entering the ocean and an increase in local pH at the deployment site from 7.95 to 8.3, representing a return of ocean alkalinity to pre-industrial levels. The experiment showed no significant damage to creatures such as plankton, fish and lobster larvae, although the team did not measure the impact on adult fish or marine mammals.
To some, using chemicals to solve an environmental problem seems reckless. “What we’re seeing is a push to exert finer control over natural systems,” says Benjamin Day, a senior climate and energy justice campaigner at Friends of the Earth US. Day says he is “deeply concerned” about the large-scale environmental impacts of the OAS, including the risk of “unforeseen catastrophic consequences.”
But, whether we like it or not, we are already experimenting with the climate, in an uncontrolled way. “We really need to think about this in management terms,” says Phil Renforth, a carbon dioxide removal (CDR) expert at Edinburgh’s Heriot-Watt University. “We are adding CO2 into the atmosphere every year. “A huge proportion of that goes into the oceans, and the real question is: can we be proactive about how we manage it?”
In practice, OAS is a lot like liming, which Greek farmers first used 2,000 years ago to neutralize the acidity of their fields. More recently, in the 1980s, Scandinavian rivers suffering from a decline in fish due to acid rain were given heavy doses of alkaline lime; Reported successes include the return of native salmon to Sweden’s Ätran River.
There are already numerous OAE startups verified to sell carbon credits through an international carbon removal registry, Isometric. These credits are being purchased by companies that intend to bill their businesses as net zero.
However, it is still unclear whether the OAS operates safely at the level required to achieve a climate benefit. Subhas’ team, which includes researchers from Woods Hole Oceanographic Institution, Rutgers University and the Environmental Defense Fund, is the first to test this in open water.
Their plan now is to model, using ocean data, how the chemical plume continues to absorb CO.2 over time. “In the best case scenario, this dispersion would lead to the absorption of about 50 tons of carbon dioxide from the atmosphere into seawater over the course of about a year,” says Subhas. In comparison, 50 tonnes of carbon is equivalent to the annual emissions of five UK citizens.
If that seems insignificant, it’s because the team, which has no commercial ambitions with OAE, started small, to demonstrate best practices in a field that is rapidly evolving. “If these experiments need to be done, we want them to be done by respected, objective, transparent research institutions that are making a real effort to engage and involve us along the way,” says Sarah Schumann, a commercial fisherman who joined the research team as an at-sea observer.
Prior to his participation, Schumann attended five of 50 meetings (conducted in person by the scientists) with fishermen, tribal leaders and stakeholders along the Massachusetts coast, to address local concerns prior to the field test.
While Schumann says local fishermen have experience collaborating with researchers and generally trust science, “there was a lot of concern that this could become a Trojan horse that would allow other players to get a foot in the door,” he says, referring to the fact that commercial operators are interested in proving that OAE is effective and therefore eligible for carbon credits.
Schumann is not alone in this concern. “We’re getting a lot of companies that are just getting ahead of this,” Day says, “and they’re being facilitated by some technology companies that were very eager to offset their emissions.”
But for OAS to become a meaningful technology, it will likely require public and private investment. The US National Oceanic and Atmospheric Administration says it could remove 1 billion to 15 billion tons of CO2 annually at a cost of up to $160 (£120) per ton.
“There are not many places on our planet where we can store carbon,” says Renforth. “We shouldn’t rule anything out until we actually have a viable solution across the space.”
