Several unnamed Canadian regions will be recruited this year to help expand the testing of a controversial theory - where adding tons of magnesium hydroxide to waters surrounding coastal communities will become a new effective tool in the urgent battle against global warming.

The first test, in the port of Halifax, NS, poured 278 tons of the mineral into the Atlantic Ocean waters between October and December 2023. Based on initial measurements, the pilot indicated that discharging the mineral through municipal water pipes was safe, according to Planetary Technology, the Halifax-based company behind this technology.

All early results suggest that there was no impact on any ecosystem inside the harbor, said Mike Killand, co-founder and CEO of Planetary Technologies: "So I can call it a big success."

The mineral - often used as a laxative, deodorant, and fire retardant - is sourced from a mine in China, according to the company. When mixed with water, it dissolves and changes its pH level, enhancing the natural absorption of carbon from the air.

While data from the Halifax experiment is still undergoing full analysis, Killand says the company plans further tests in other Canadian communities in 2024, although locations have not been specified.

Although the Halifax test passed without much public discussion or feedback, the same proposal has turned the usually quiet community of St Ives Bay on the southwest coast of the UK into an escalation of protests.

Su Sayer, founder and director of the Seal Research Fund in Cornwall, UK, said: "The more we learn, the more concerned we become." The area's scenic landscapes make it a tourist attraction. It is also home to more than 20 marine life conservation groups, which have started raising questions.

Sayer and others launched letter-writing campaigns and protests after learning that the Canadian company and the public were preparing for an experiment that would release almost the same amount of magnesium hydroxide used in Halifax - about 300 tons - into the bay.

Sayer said: "We were concerned about the effects on the ecosystem. We were concerned about the fact that there is no governance, at the national or international level, for this matter."

Killand said he was surprised by the reaction.

He added, "We came, I think, with a very scientific view of the world," adding that the company listened to the community. Magnesium hydroxide has not yet been tested, and the UK government commissioned a report, due to be released in the coming weeks, including independent advice on how to proceed with the company's proposals.

Sayers explained: "This was supposed to happen very quickly. When they spoke to us in January (2023)." "They said the release would happen in March 2023... but it didn’t happen yet. And I’m really glad because that now means due diligence might be properly conducted.

Enhancing ocean alkalinity

The oceans - which already hold nearly 40 trillion tons of carbon dioxide - naturally absorb carbon from the air, which contains nearly a trillion tons.

But an increasing number of companies want to boost the oceans’ ability to store carbon dioxide by mixing minerals like magnesium, Killand says carbon capture occurs as the magnesium dissolves and lasts a long time.

He said, "It lasts for 100,000 years in the ocean," which is also an urgent task, according to the company.

Killand added: "The scale of the climate crisis as we feel it now means we will need a solution that is as cheap and effective as possible."

As more companies enter the emerging carbon capture field, questions are rising about the use of waters shared by other countries along with the complex ecosystem beneath the waves.

David Santillo, marine biologist and scientist at Greenpeace based in London, UK, said: "You can’t change ocean chemistry without biological impacts."

He added, "It’s basically an open experiment with the environment." "You have no way to control things or undo things if things don’t go as planned."

In October 2023, 100 countries, part of a group called the London Convention and Protocol, discussed enhancing ocean alkalinity and other forms of marine geoengineering, and declared their intention to regulate projects that would change ocean alkalinity due to the "potential for widespread, long-term, or severe adverse effects."

But Killand says these regulations don’t necessarily apply to Planetary Technology’s work, because the organization monitors the dumping of materials into oceans from ships, not the release of chemicals through municipal water pipes, which is how magnesium is poured into the water.

As for other concerns, he says the company is proceeding cautiously and in parallel with scientists at Dalhousie University in Nova Scotia, who receive funding from the Natural Sciences and Engineering Research Council of Canada.

Killand said: "There is no way we know enough to do this at scale." "But no one is suggesting we do it. I think what we are proposing now is to do it on very small scales, learn, and move forward, move forward."

There is another concern that sparked opposition in the UK, where environmental advocates worry that companies promoting marine geoengineering are driven by commercial interests through selling carbon credits to offset pollution.

Santillo said: "This is really a company doing what the company wants to do, because it feels it has a marketable product in the end."

Planetary Technologies has already won a million-dollar award from Elon Musk-funded XPRIZE Foundation and sells what Killand calls "pre-credits" to companies like Shopify, which in turn help fund the project’s research, and he says his focus now is on transparency with the communities that will help test this approach.

He added, "This won’t work if it’s not something people can feel comfortable with at the end of the day, and people won’t feel comfortable with it unless we take their concerns seriously."