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Can Mining the Seabed Help Save the Planet?

An aerial view shows wooden pontoons equipped to dredge the seabed for deposits of tin ore off the coast of Bangka Island, Indonesia, on May 1. Willy Kurniawan/Reuters

Posted on November 9, 2021

Few other issues better illustrate the messy trade-offs involved in climate policy.

The solutions to climate change—solar panels, windmills, electric cars—seem so blissfully clean and also within reach. Yet they also require vast amounts of minerals: cobalt, manganese, copper, nickel, and rare earths. Electric cars, for instance, are made with about six times more minerals than conventional vehicles, and such staggering amounts simply aren’t available now. Not on land, anyway.

Parts of the ocean seabed, lying some 15,000 feet deep, are littered with the stuff. Black, potato-sized lumps called polymetallic nodules can be found in great volumes on the oceans’ muddy bottoms. The nodules contain large amounts of copper, manganese, nickel, and cobalt, as well as other minerals in smaller amounts. Extracting the nodules would ease the pressure for mining on land at a time when ore yields are falling and environmental and social costs are rising. If it can be done efficiently and at scale, mining the seabed could lower the cost of electric vehicles, increasing their sales and slowing emissions.

“We have a renewables transition that has to be done to combat climate change, and the window is less than 10 years to keep things under 2 degrees Celsius,” said Steve Katona, a marine biologist and ocean mining consultant. “If we don’t get the metals we need from nodules, we’ll get them from land, but that just means mines will have to be enlarged or new ones will have to be created. And a lot of the new nickel will probably come from tropical rainforests, which have much more biodiversity than the seabed.” Katona is a co-founder of the Ocean Health Index and a consultant to the Metals Company, a Vancouver-based start-up that aims to be the first to commercially extract minerals from the seabed.

Many environmentalists aren’t buying his argument. The Deep Sea Conservation Coalition, which encompasses virtually all of the leading ocean conservation organizations, has called for a 10-year moratorium on such mining until its effects are better understood. Seabed mining “would irreversibly destroy ancient deep-sea habitats, impact those who derive their livelihoods from the ocean (for example from fisheries), and risk disturbing the planet’s biggest carbon sink,” the group warned in a public call for action.

WWF has launched a no deep seabed mining initiative. “Negative effects on global fisheries would threaten the main protein source of around 1 billion people and the livelihoods of around 200 million people, many in poor coastal communities,” it reported in February. “We don’t see any pros. We see only cons,” said Arlo Hemphill, a senior oceans campaigner at Greenpeace USA. “There is no reason to start a new destructive extractive industry in the world’s oceans.”

Electric cars are made with about six times more minerals than conventional vehicles, and such staggering amounts simply aren’t available now.

How this debate plays out could have significant consequences—for the oceans and also for the planet’s overall climate. Few other issues show better the challenges of dealing with global warming and the messy trade-offs that are likely to be involved. Mining the oceans on a large scale could be highly destructive; not mining could hinder efforts to quickly ramp up the use of renewables or require even worse environmental damage on land. Predictably, billions of dollars are also at stake.

Nobody doubts the need for more minerals. The International Energy Agency predicts that between 2020 and 2040—in a scenario where the world is on track to meet the Paris Agreement’s goals—demand for copper will triple, manganese will increase 8 times, nickel 19 times, and cobalt 21 times. Mines are being opened or expanded from the Andes to the Congo, but all of that added production won’t be nearly enough. By one estimate, for instance, the global battery-electric car fleet will reach 1 billion by the middle of the century. According to a study, the battery for a single Tesla Model 3 requires 56 kilograms of nickel, 7 kg of cobalt, 6.6 kg of manganese, and 85 kg of copper. Times 1 billion, the total amount of these four metals—the main ones found in seabed nodules—is 155 million metric tons.

That increases pressure to get seabed mining underway quickly—without provoking an environmental backlash.

The United Nations-affiliated International Seabed Authority (ISA), based in Kingston, Jamaica, has already spent seven years drafting precise rules on how polymetallic nodules can be responsibly collected from the seafloor. ISA Secretary-General Michael Lodge says the rules should be finalized and ready to be approved by the 167-country assembly by 2023. “This is the first time an entirely new industry has had to bake environmental rules into its plans even before it starts,” Lodge said. “It gives environmental organizations a unique opportunity to weigh in and make sure the rules are as stringent as possible.”

One of the best potential areas to harvest mineral-rich nodules is the Clarion-Clipperton Zone, west of Mexico and south of Hawaii. At 1.7 million square miles, the overall zone is larger than India, though only a tiny fraction of that is slated to be exploited. The first areas to be mined, in the next two decades, have already been allocated by the ISA to the Pacific nations of Nauru, Kiribati, and Tonga. Those areas total about 29,000 square miles, which is almost the size of Maine.

Those may sound like large areas for industrial-scale underwater extraction—after all, mines on land tend to be in the single-digit square miles. But the targeted 29,000 square miles represent just 0.02 percent of the global seabed. The very first concession slated for exploitation by the Metals Company in partnership with Nauru, some 1,500 square miles, represents just 5 percent of that 0.02 percent.

The mining won’t involve any digging or dredging: A tracked, automated “crawler” will suck up the nodules and send them up a tube to a production ship floating 15,000 feet above, creating a plume of mud that initial tests suggest will eventually settle back on the seafloor (though how fast is being disputed), much like a truck traveling on a desert track. This year, a test by another mining company, Global Sea Mineral Resources, was successfully performed—until the crawler got stuck at the bottom of the sea.

On the ship, the nodules will be rinsed. They will then be transferred to an ore carrier ship that will deliver them to a smelter on land, likely in the United States. The muddy water left over from the rinsing process won’t be released at the surface, where it could harm marine life, but will be sent back down through a second tube ending at a midwater depth, tentatively set at 4,000 feet.

An estimated 95 percent of the mud plume will settle back on the bottom, but the last 5 percent in midwater is seen as a danger by some marine biologists and fisheries scientists. Marine life at that depth is relatively abundant, even if no fishing takes place there. Tuna, in particular, could be affected, as they prey on some of the species that swim through this zone as they migrate to and from the surface.

“If water from processing nodules has to be discharged, it should be done as close to the bottom as possible,” said Leslie Watling, a professor of marine biology at the University of Hawaii and co-author of a paper on the environmental effects of seabed mining. It may cost more, he added, “but if they can lift the nodules from the bottom at that depth, they can bloody well put the sediment back at that depth.” Gerard Barron, the Australian CEO of the Metals Company, says his company would be ready to comply. “We want the science to tell us how deep to release the midwater plume of mud,” he said. “We’re now told that the optimal level will be 1,000 meters to 1,500 meters [3,300 to 4,900 feet] below the surface. But if further scientific studies tell us that the midwater discharge should go back to the seafloor, then that’s what we’ll do.”

So far, Google, BMW, Volvo, and Samsung have pledged not to use metals from nodules until more is known about mining’s effect on the seabed.

According to research funded by the Metals Company, the smelting process will produce 80 percent less toxic waste than onshore mining for cobalt, 60 percent less waste for nickel, and about 50 percent less for copper and manganese.

The call for a moratorium hasn’t convinced all scientists. Craig Smith, a seabed ecologist at the University of Hawaii, hasn’t signed on. He notes that this kind of mining is untested and wouldn’t be under a moratorium. “The Clarion-Clipperton Zone is right in the middle of the Pacific’s Hurricane Alley,” he noted. “It makes more sense to allow one company to start mining and then have it closely monitored by independent scientists.” Neil Craik, a professor of environmental law at the University of Waterloo, near Toronto, is more sanguine. “My own sense is this is no Deepwater Horizon,” he said. “The immediate risks look more like those in shipping—manageable.”

Still, obstacles loom. The start-up costs for each mining operator are estimated at several billion dollars, and opposition from environmentalists could have a chilling effect on financing. So far, Google, BMW, Volvo, and Samsung have pledged not to use metals from nodules until more is known about mining’s effect on the seabed.

The ongoing debate over the potential benefits and downsides of seabed mining could have huge impact. On the one side of the debate are those who say the direct carbon contribution of sea mining to the atmosphere is negligible—and much lower than mining on land. And opening new mines on land at anywhere near the scale required won’t be easy. “There’s immense Nimbyism all over the world on mining,” said Saleem Ali, who heads the University of Delaware’s minerals, materials, and society program and whose research is funded by the Metals Company. “It’s more and more difficult to get permits for new mine sites.”

Other scientists, however, warn of largely untested technology and unpredictable outcomes. Smith says testing so far has consisted of sending a small replica of a mining machine—one-fifth the size of an operational one—to the ocean bottom to scoop up nodules and retrieve them, without sending them through pipes to a production ship. He worries that mining companies are minimizing accident risks.

As head of the ISA, Lodge sits at the nexus of this debate. He seems unfazed. Seabed mining “will start slowly, and the authority will take a precautionary approach,” he said. “I don’t think it’s likely that there would be more than a small number of concurrent operations in the foreseeable future.”

For its part, the Metals Company is moving full speed ahead. The firm’s partner and investor, Allseas Group, a Swiss-based subsea construction company, bought an oil drilling ship from Brazil’s Petrobras for $15 million last year. The plan is to turn the Vitoria 10000 into the world’s first subsea mining vessel. Renamed the Hidden Gem, the 748-foot vessel arrived in the Dutch port of Rotterdam in September for a makeover that will enable it to lift to the surface 3 million metric tons of nodules a year.

The ship will be operated exclusively by the Metals Company. “We expect to be in production by 2024,” Barron said, “and we expect to be the first, possibly by up to three years.”

For better or worse, the race is on.


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