Why deep-sea mining is risky for everyone

Huge reserves of metals lie deep in the ocean, but extracting them poses environmental, scientific, financial and political risks.

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In the total darkness of the Clarion-Clipperton Zone, five kilometres beneath the surface of the Pacific Ocean, the seabed is strewn with potato-sized lumps. These potatoes – polymetallic nodules, to give them their proper name – take millions of years to grow, from the gradual accumulation of manganese, nickel, copper and cobalt, but they are far from rare. They are found on the seafloor across the world, inspiring avarice and foreboding in equal measure. They hold hundreds of billions of tonnes of valuable metals, but the race to exploit these resources could create a new environmental catastrophe.

Unlike other natural resources, most of the metal and minerals on and under the seabed are not owned by any one nation, because they are not within any nation’s border.

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Instead, they are overseen by the International Seabed Authority (ISA), an autonomous body set up under the 1994 United National Convention on the Law of the Sea (UNCLOS). The ISA is mandated with organising and controlling deep-sea resources for the “common heritage of mankind”.

But since 2001, the ISA has also issued 30 exploration contracts, covering an area of 1.4 million square kilometres, to companies and national governments looking to develop these resources. The metals in the deep sea could, say adherents, power a transition to renewable energy and clean transport. But many in the scientific community reject this idea.

“It is inconceivable to think of [deep-sea mining] as green,” says Craig Smith, a professor of oceanography at the University of Hawaii, during a recent deep-sea mining webinar hosted by Oxford University. “The footprint of impact of seabed mining will likely be larger than any other industrial activity on the planet, if it goes to the full scale envisioned.”

“Land-based mining is pretty mucky stuff as well, and has certainly led to environmental catastrophes in the past,” says Ian Coles, a partner at the law firm Mayer Brown who specialises in mining. “The difference is that there's so much that's unknown right now about the environmental consequences of deep-sea mining, because it's not been done before.”

Where an economic opportunity exists, however, arguments for exploiting it will be found.

Rob Langman, a director of UK-based of consultancy MarineSpace, which is involved in marine aggregate extraction, says mining the deep sea “could have sustainability aspects in terms of providing greater consumer choice of where minerals come from. Rather than sourcing cobalt, which is used in lots of modern battery technology, from the Democratic Republic of Congo (DRC), companies or consumers could choose a different option.” DRC has the world’s largest deposits of cobalt, but tech firms are coming under increasing pressure to boycott its mines over human rights concerns, particularly related to child labour.

Others see deep-sea mining as a way to break the near-monopoly that China and Chinese companies have on the production of rare-earth metals.

The contracts also require that portions of all mining revenues are redistributed, with investment in research and the policing of regulations, while ISA’s draft regulations require that half of all seabed surveyed is left untouched.

However, Louisa Casson, a campaigner in Greenpeace’s oceans team, points out that the fact that conflict minerals are currently used does not justify any other means. What’s more, the companies that miners say will use these minerals for environmental good may not be interested in them by the time they’re available. “We haven’t heard any demand for deep-sea mining cited by battery manufacturers, by renewables companies, or by EV (electric vehicles) producers,” says Casson.

In fact, both Tesla and Panasonic have recently said they intend to develop cobalt-free batteries due to human rights concerns.

“What we really need to be encouraging”, says Casson, is “smarter production design, with less need for raw materials, and then government incentives for better reuse and recycling.”

Companies are most interested in polymetallic nodules, but these are not the only deposits for which the ISA is issuing licenses. Deep-sea vents, which some scientists suggest may have been the starting point for life on Earth, and cobalt-rich crusts in shallower seas are also rich in valuable minerals.

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To mine the polymetallic nodules, a mining head would chop up the sediment to dislodge the nodules, which would then be pumped to the surface. Anything living on or around the nodules would not survive.

Craig Smith describes the environment that has evolved around the nodules as they have formed over millions of years: more than 100 species of specialised fauna have adapted to live in the nodules themselves, while the sediment beneath is the habitat for a range of other species.

But the process would have much more widespread effects. Mining creates both a sediment plume on the ocean floor and a “dewatering” plume that is released by the vessel as it dumps everything that has been pumped up with the nodules. A single mining operation, says Smith, can create a sediment plume of 2,000 square km, interfering with the ability of species in that area to feed, mate and survive.

But Smith says the full impact of seabed mining will not be fully understood until an operation is implemented. “The footprint of disturbance from mining, especially if all the licenced mining areas under consideration are mined, is extremely large and much of the impacts will be permanent.”

But there are also reasons to think this may not happen immediately. In October, the 26th session of the ISA assembly came and went without a draft mining code being agreed. Without the code, no exploitation can occur in international waters.

Ian Coles points out that the 30 contracts issued so far are “hardly a cascade”, and calls the process for issuing permission to exploit the deep sea “sclerotic”. “The regulations that need to be finalised before any exploitation can take place have been in the hopper for many years,” he says.

This is not only a matter of environmental concern; many African countries with mining industries are concerned what a greater supply of metals would do to prices, while all countries are concerned by how costs and revenues would be shared under the ISA's financial model.

Rob Langman says deep-sea mining “will probably happen in a national jurisdiction” – closer to shore – before it happens in international waters. And, indeed, several mining licences have already been issued within national jurisdictions. The Cook Islands granted exploration licences in 2020 after agreeing a mining code, while Norway introduced a seabed mining law in 2019.

Papua New Guinea was the first country to undertake an exploitation project, but Solwara 1 was abandoned before any minerals were extracted. Its developer, Nautilus, entered administration in 2019 at a cost of $120m to the PNG government.

Such an experience might give pause to other island nations, such as Nauru, Tonga and Kiribati, which have sponsored exploration work undertaken in the Clarion-Clipperton Zone by the Canadian company DeepGreen.

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But private companies also have reason to be cautious. What investors seek more than anything is certainty of returns, something deep-sea mining, with its huge upfront costs and technical challenges, cannot provide at present. The environmental impact of deep-sea mining may also rule out many investors.

What could happen, then, is that deep-sea mining will remain controversial but mostly theoretical until a tipping point occurs. A wealthy state, such as Norway, China or the US (which is not a member of the ISA), could choose to fund exploitation, opening up the market for others. Or, perhaps, the prices of commodities found on the seafloor may rise enough to create a clear business case for companies, whatever the scientific opposition.

Then again, there is always the chance that a lack of international consensus, and a growing awareness of how the devastation of marine environments directly impinges the global economy, could prevent the large-scale exploitation of the seafloor. This has not been the story with other natural environments, from the Arctic to the Amazon. It will take great political effort if the abyss is to remain undisturbed.

Jon Whiteaker is a senior editor at Investment Monitor.

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