Mr Viral
A growing industry is racing to engineer a solution to global warming, using the absorbent power of the oceans which already regulate Earth’s climate by absorbing heat and carbon. Dozens of companies and academic groups are pitching the same theory: that sinking rocks, nutrients, crop waste or seaweed in the ocean could lock away climate-warming carbon dioxide for centuries or more. Nearly 50 field trials have taken place in the past four years, with start-ups raising hundreds of millions in early funds. Most companies looking offshore for climate solutions are trying to reduce or transform the carbon dioxide stored in the ocean.
Planetary Technologies launched an experiment in Halifax Harbour, Nova Scotia, using magnesium oxide and added a red dye to trace the flow. When dissolved into seawater, it transforms carbon dioxide from a gas to stable molecules that won’t interact with the atmosphere for thousands of years. “You add an alkaline or a basic mineral to the ocean and that mineral is essentially an antacid,” explains Will Burt, chief ocean scientist for the company PlanetaryTecnologies. “It neutralizes acid the same way an antacid neutralizes acid in your stomach.”
Planetary’s testing so far suggests that magnesium oxide poses minimal risks to marine ecosystems, plankton, or fish. The mineral has long been used at water treatment plants and industrial facilities to de-acidify water. Limestone, olivine, and other alkaline rocks have the same effect. Other companies are focused on growing seaweed and algae. These marine organisms act like plants do on land, absorbing carbon dioxide from the ocean just as trees do from the air. Still others view the deepest parts of the ocean as a place to store organic material that would emit greenhouse gases if left on land. But the field remains rife with debate over the consequences for the oceans if the strategies are deployed at large scale, and over the exact benefits for the climate.
David Ho is an oceanography professor at University of Hawaii, and co-founder of nonprofit [C]Worthy, which works on verifying the impact of ocean-based carbon removal. “The experiments that are being done now and the scale at which they’re being done, it’s pretty safe. The question is what happens when you scale it up to billions of tons every year? And that’s still to be determined, ” says Ho. “For this to work, carbon dioxide removal has to go from something that most people have never heard of to the largest thing that humanity has ever done in a really short time. And it’s daunting” he adds.
Critics say the efforts are moving too quickly and with too few guardrails. In North Carolina, a request to dump shiploads of olivine near the beachside town of Duck received questions that downsized the project by more than half. Fishing communities have opposed a project by the Woods Hole Oceanographic Institution based on Cape Cod, Massachusetts.
The nonprofit research group has been meeting with community members and is still waiting on a permit from the U.S. government to pour a sodium hydroxide solution into the ocean. “You don’t dump poison on your farmland. You don’t dump poison in the ocean,” says Meghan Lapp who works for the fishing company SeaFreeze Ltd. “To be doing that in the name of carbon capture to me is just irresponsible.” Another project by Planetary Technologies was halted in Cornwall, England in the spring of 2024 after stiff community resistance.
Most of the ocean start-ups are selling carbon credits — or tokens representing one metric ton of carbon dioxide removed from the air. Largely unregulated and widely debated, carbon credits have become popular this century as a way for companies to purchase offsets rather than reduce emissions themselves. The industry sold more than 340,000 marine carbon credits last year, up from 2,000 credits four years ago, according to the tracking site CDR.fyi. But that amount of carbon removal is a tiny fraction of what scientists say will be required to keep the planet habitable for centuries to come. Even if these solutions do work long term, most companies are operating on too small of a scale to influence the climate.
Expanding to meet current climate goals will take massive amounts of resources, energy and money. “There’s a challenge in the amount of energy that’s needed, the amount of stuff we need to move around, the infrastructure that’s needed. And there’s also the challenge of who’s going to pay for it because it’s going to cost trillions of dollars every year.” says Ho.
Planetary’s Burt imagines a future in which minerals are pumped out through power plants and water treatment facilities on every major coastline in the world. But that would require a large, steady volume of magnesium oxide or similar minerals, along with the energy to mine and transport them. “We can’t spend half a century digging into the details of how the solution might work, because the whole point here is to mitigate against a rapidly accelerating climate crisis. That’s why we’re here. So we have to act with safety and integrity, but we also have to act fast,” says Burt.
There’s a risk that these projects exacerbate environmental harm that isn’t detectable in small trials, and because of global water circulation, could be felt around the world. But the alternative to never trying, Ho said, is unabated climate change.
Last year marked the hottest year in Earth’s history, even as global carbon emissions are projected to reach another all-time high.
— This story was supported by funding from the Walton Family.
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