A cluster of candy cane-striped smoke stacks dots the horizon of Tufts Cove in Nova Scotia, Canada. Deep in the briny depths of Halifax harbour, something huge is happening: the ocean is being engineered to remove atmospheric carbon.
“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.
Planetary Technologies is an ocean carbon-removal firm and one of a growing number of companies attempting to decrease excess atmospheric carbon – the main driver of the climate crisis – by speeding up naturally occurring carbon cycles in the ocean.
To do this, the company conducts ocean alkalinity enhancement (OAE), adding a chalk-like substance to the seawater, which allows the water to absorb and store more atmospheric carbon than usual.
This process also helps to offset ocean acidification, often called the “evil twin” of the climate crisis, which is increasing dramatically.
Because it relies on an already occurring process, proponents say these technologies will not harm the marine creatures that call this harbour home, such as mackerel, sunfish, harbour seals and sea turtles. But some marine scientists worry that adding any extra materials to an already stressed ecosystem might harm aquatic life and say that this field of marine geoengineering 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.”
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 to create an odourless milky composite, which is then discharged into Halifax harbour and monitored by their sensors.
Bolstered initially by small government grants, venture funds and other private capital, Planetary Technologies now generates revenue by selling carbon-removal credits worth millions of dollars to companies such as JPMorgan Chase and Shopify.
Ocean carbon removal is a fledgling industry but one that has seen more than $500m (£370m) invested since 2021, according to Ocean Carbon Removal Watch, a database launched by the Pulitzer Center, which tracks marine carbon dioxide removal (mCDR) investments.
After over a decade of protracted negotiations among scores of countries, this October the International Maritime Organization (IMO) adopted the first international framework that officially acknowledges the three major ocean carbon removal techniques: ocean fertilisation, ocean alkalinity enhancement and biomass sinking.
Adopted in London during the annual meeting of the London convention and protocol, a little-known but influential treaty that governs the dumping of waste at sea, the new framework urged a cautionary approach. The IMO said in a statement that “further scientific research is needed before any activities beyond the research stage can be considered”. But it acknowledged that “marine geoengineering is attracting increasing scientific, commercial and public attention”.
“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 organisation. “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.”
However, some scientists and conservation organisations fear the private-sector market is moving ahead too fast and risks creating technologies that damage the ocean and potentially cloud the sector before real breakthroughs are made.
Brad Ack, chief executive of Ocean Visions, a conservation organisation thatpromotes creative 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 this sector began, has increasingly dried up.
Nova Scotia, known for its cod fishing history and legendary tides, is now the largest ocean alkalinity-enhancement centre in the world. Anchored by Dalhousie University’s Ocean Frontier Institute and bolstered by grants from the Canadian government and partnerships with research institutions in Germany and Australia, the private companies CarbonRun and pHathom Technologies are also operating there, in addition to a test site run by Carbon to Sea, a non-profit scientific research programme.
But as the Halifax hub continues to grow, and other field trials are proposed across the world in places as varied as the Gulf of Mexico, the Gulf off Saudi Arabia, Norway’s rivers or the harbours of Singapore, the wider field continues to face questions. Since the sector is so new, it is unclear how existing maritime laws can be applied, for example, and where exactly 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.
At the same time that governance is being negotiated, 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 the trace metals in them 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, which are the base of the marine food chain.
Although there are scientists investigating the environmental impacts of alkalinity enhancement on marine life, it remains understudied globally.
Bednaršek is working with the Intergovernmental Panel on Climate Change (IPCC) to develop a methodology for accounting for carbon removal through ocean alkalinity enhancement which, similar to the recently released IMO framework, which 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 emeritus 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.
But many of those involved in the business of carbon removal argue more legislation means more delay in scaling up the industry, which is time the ocean, and the planet, do not 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 at Planetary Technologies.
“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.”
Additional reporting by Allison Gacad. This story was produced in partnership with the Pulitzer Center and with the support of an Alicia Patterson fellowship
