First global rules on ocean geoengineering land on a $500m industry

More than $500m (£370m) has flowed into ocean carbon removal since 2021, according to Ocean Carbon Removal Watch, a database launched by the Pulitzer Center that tracks marine carbon dioxide removal (mCDR) investments. Now, for the first time, that money operates under an international framework.

This October, after more than a decade of negotiations among scores of countries, the International Maritime Organization (IMO) adopted the first international framework officially acknowledging the three major ocean carbon removal techniques: ocean fertilisation, ocean alkalinity enhancement (OAE) and biomass sinking. The IMO adopted it in London during the annual meeting of the London Convention and Protocol, a little-known but influential treaty governing the dumping of waste at sea.

The framework urged caution. The IMO said in a statement that "further scientific research is needed before any activities beyond the research stage can be considered", while acknowledging that "marine geoengineering is attracting increasing scientific, commercial and public attention".

What does the ruling change for practitioners?

For the companies selling credits and the buyers purchasing them, the IMO framework is the first real governance anchor in a sector where jurisdiction is murky. Because the field is so new, it remains unclear how existing maritime laws apply and where their jurisdiction starts.

"This creates opportunities for bad actors to exploit gaps in the regulatory regimes," says Romany Webb, deputy director of the New York-based Sabin Center for Climate Change Law.

The signal matters commercially. "The IMO assessments are sending a strong signal to governments and industry alike that this is something that we, as a global community, prioritise," says Fatima Candace Vahlsing, vice-president for climate at Ocean Conservancy, a US-based nonprofit. "Whether you're a business or an academic or a nonprofit, everyone wants the system to work and there to be trust around the system."

Trust is exactly what credit buyers are buying. Planetary Technologies, an ocean carbon-removal firm, now generates revenue by selling carbon-removal credits worth millions of dollars to companies such as JPMorgan Chase and Shopify. Bolstered initially by small government grants, venture funds and other private capital, it has turned an experimental process into a paying business.

Inside the Halifax operation

At Tufts Cove in Nova Scotia, Canada, Planetary Technologies runs its operations five days a week. Working out of a shipping container, it adds an alkaline slurry — its proprietary formula — to a local power company's cooling water, creating an odourless milky composite that is discharged into Halifax harbour and monitored by its sensors.

The company conducts OAE: adding a chalk-like substance to seawater, which allows the water to absorb and store more atmospheric carbon than usual. The process also helps offset ocean acidification, often called the "evil twin" of the climate crisis.

"This is what Mother Nature has done naturally for a few billion years in order to rebalance the atmospheric and ocean chemistry over long timescales," says Dr Greg Rau, co-founder and senior scientist at Planetary Technologies.

Nova Scotia, known for its cod fishing history and legendary tides, is now the largest ocean alkalinity-enhancement centre in the world. It is anchored by Dalhousie University's Ocean Frontier Institute and bolstered by Canadian government grants plus partnerships with research institutions in Germany and Australia. The private companies CarbonRun and pHathom Technologies also operate there, alongside a test site run by Carbon to Sea, a non-profit scientific research programme.

Other field trials are proposed across the world — in the Gulf of Mexico, the Gulf off Saudi Arabia, Norway's rivers and the harbours of Singapore.

The science risk investors can't ignore

Proponents argue the technology relies on naturally occurring carbon cycles and will not harm marine creatures in the harbour, such as mackerel, sunfish, harbour seals and sea turtles. Some marine scientists disagree and say the field needs more research.

"If we develop a new medicine, you have steps that you're supposed to take. You don't just find a substance and just implement it," says Sam Dupont, a senior lecturer at the University of Gothenburg. "And at the moment, with [ocean carbon removal] it seems you're jumping to clinical trial immediately."

One material risk is emerging from the supply side. Scientists are realising that the base materials used for alkalinity enhancement are not created equally. Some materials, such as byproducts from mining, are considerably cheaper, but their trace metals can have an outsized impact on marine ecosystems.

"Even in very low concentrations, you can have toxic effects with trace metals," says Nina Bednaršek, a senior scientist at Slovenia's Jožef Stefan Institute, which specialises in biological risk assessment for mCDR. Bednaršek worries especially about zooplankton, the base of the marine food chain.

She is working with the Intergovernmental Panel on Climate Change (IPCC) to develop a methodology for accounting for carbon removal through OAE — a step that, like the IMO framework, would help with environmental safeguards and regulatory oversight.

"Right now, there is no price on the biology," says Bednaršek. "I think that's wrong."

Lisa Levin, professor emerita at California's Scripps Institution of Oceanography, agrees. "For ocean alkalinity enhancement, most of the research has examined consequences for ocean chemistry, which I don't consider an assessment of environmental risk," she says.

Rules or speed?

Some scientists and conservation organisations fear the private-sector market is moving too fast and risks creating technologies that damage the ocean, potentially clouding the sector before real breakthroughs arrive. Brad Ack, chief executive of Ocean Visions, a conservation organisation promoting solutions to conserve and restore the ocean, says the sector needs significant public investment to set rules and standards.

"That's largely being done by the private sector and the academic sector at this point, and that's not enough," he says. Government funding, particularly in the United States, where the sector began, has increasingly dried up.

Industry's counterargument is timing. Many involved in carbon removal argue that more legislation means more delay in scaling up — time the ocean, and the planet, don't have.

"Conservation tends to sort of have this kneejerk reaction that any time you do anything in the ocean … out of the ordinary, it's got to be bad," says Rau. "They need to understand that we're beyond that point here – we are damaging the ocean. You can put all the fences you want around a certain area of the ocean, but it's going to warm and it's going to acidify."

For credit buyers and operators, the practical takeaway is straightforward: the IMO framework legitimises the sector's three core techniques but stops short of permitting commercial deployment. The next files to watch are the IPCC's accounting methodology and how governments fill the jurisdictional gaps the IMO left open — both will determine what a tonne of ocean-removed carbon is actually worth.