The UN has granted 30 licences for exploration deep under the ocean

The UN has granted 30 licences for exploration deep under the ocean

 Why mine the seabed?

Because under the global seafloor, there are more valuable minerals than in all the Earth’s continents combined. These areas have been known for decades to contain vast untapped reserves of copper, gold, and many other sought-after elements. The main prize, however, is cobalt – a key component in lithium-ion batteries that power everything from iPhones to electric cars. Cobalt is still predominantly mined in the Democratic Republic of the Congo, often by child labourers. But stung by criticism of their supply chains, mining companies – along with electrical, automotive and green businesses – are now exploring new ways of sourcing it.

Where are these minerals found?

There are two main sources under the sea. First, the “polymetallic nodules” that form on the abyssal plains of the global ocean – the vast, sediment-covered plains that lie about 3,000 to 6,000 metres down, between continental shelves and mid-ocean ridges, and cover more than half of the Earth’s surface. On these plains, billions of nodules – potato-sized rocks – have formed over millions of years, probably by precipitating dissolved elements from seawater. They contain large amounts of “critical metals” – cobalt, nickel, titanium, manganese and rareearth elements – all crucial to hi-tech industry. The second main source is the area around hydrothermal vents, the fissures on the sea floor, where massive volcanic sulphide deposits develop. These deposits are rich sources of cobalt, silver, gold, copper and zinc.

What are the origins of deep-sea mining?

In 1965, John L. Mero, the “father of ocean mining”, kick-started the business with his book The Mineral Resources of the Sea. But it gained traction thanks to an extraordinary covert operation. In 1974, a huge US ship set sail for the mid-Pacific equipped with state-of-the-art drilling technology. Its mission – so it was claimed – was to extract metals from rocks on the seabed. In reality, the $500m project was a front for the US to search for a Russian K-129 Soviet nuclear submarine, which had sunk 1,500 miles northwest of Hawaii. The mission to salvage the sub was largely a failure – part of it was raised, though nothing of much value – but it had an unintended consequence. During the course of the mission, some nodules were harvested by the ship. “We made ocean mining seem a lot more credible,” said David Sharp, a CIA veteran involved in the project.

How much has been done?

Lured by the prospect of untold riches, many of the world’s largest mining corporations have launched deep-sea operations, but to date, only about 5% of the ocean’s floor has been explored. Deep-sea mining trials have taken place near Okinawa in Japan. In 2018, ships operated by the De Beers Group extracted 1.4 million carats of diamonds from the shallow seabed off the coast of Namibia. Nautilus Minerals’ project to mine hydrothermal vents off the coast of Papua New Guinea suffered “total failure” late last year, amid local resistance and funding difficulties.

How will the mining work?

The engineering challenge is huge: it will involve building remote-controlled machines operating at depths of up to three miles below the ocean’s surface and attached to huge mining ships on the surface. The undersea collection vehicles, which would need to withstand pressure of up to 900 tonnes per square foot, would creep along the bottom, scraping through the top of the seafloor, and using vacuum hoses to suck nodules and sediment to the surface. There, ores would be extracted and stored on the ship; and the valueless tailings would be pumped back into the water.

What would be the environmental impact?

The deep sea is one of the least-understood ecosystems on the planet (see box). Critics fear that mining it could be devastating. Scraping the seabed would destroy the habitat of organisms that live there. Tonnes of sediment would be released, both during extraction and when tailings are dumped: this waste could travel tens or perhaps even hundreds of miles. There are fears that these sediment plumes, some containing toxic substances, could smother marine life. Critics also warn that the mining could disrupt carbon stores in seabed sediments. Among those who have raised the alarm is Sir David Attenborough, who has written that “the rush to mine this pristine and unexplored environment risks creating terrible impacts that cannot be reversed”.

So why would we do it?

Obviously, for the money. But there’s an environmental argument too: it may be the least damaging way of securing the minerals needed for the electric car revolution – land-based mining could prove far more harmful. Scientists from the Natural History Museum estimate that to meet electric car targets in the UK alone would require twice the current annual worldwide cobalt output. “If you want to make a fast change, you need cobalt quick, and you need a lot of it,” Laurens de Jonge, who leads the EU’s Blue Nodules deep-sea mining research project. Many experts now believe it will happen. “It is an inevitability”, said Professor David Cronan, a geochemist at Imperial College.

When and where will it happen?

No commercial mining is under way yet. International waters are regulated by the International Seabed Authority (ISA), a UN-affiliated organisation based in Jamaica. And it emerged last year that it had granted 30 licences to private companies to carry out the exploration on the seabed at depths over 200 metres. In total, the licences cover an area of 500,000 square miles (more than five times the size of the UK) in the Atlantic, Pacific and Indian Oceans. Most of the licences authorise contractors to exploit a single deepwater plain, the Clarion- Clipperton Zone in the Pacific, which extends across 1.7 million square miles between Hawaii and Mexico.