It’s 04:00, pitch black, and the bed is listing wildly.

Eyes wide open after a sharp knock on the door of his small cabin, geologist Bramley Murton from the UK’s National Oceanography Centre props himself up against the swaying walls of the research vessel Discovery. He has to welcome back on deck a rather unusual crew member – a little robot that has spent the night at the bottom of the ocean, tirelessly imaging the seafloor, searching for traces of metals. A speck in the South Atlantic, 1,400 kilometres east of Brazil, Discovery is on a mission: to find cobalt-rich mineral deposits on the seafloor, a veritable bounty that could power the electronics on which we all rely.

Murton has been braving the deep blue sea for several years now, navigating the waters where the ocean floor is thought to harbour incredible riches. We’ve been promised deep sea mining as an industry of the future since the 1970s and now, after decades of delay and controversy, it could be on the verge of taking off on a vast, commercial scale.

There have already been trials off the coast of Papua New Guinea and near Okinawa in Japan, with dredgers retrieving minerals from the murky depths. If and when deep sea mining takes off, it could be an important source of the very metals that underpin our digital world – as key components of smartphones, electric cars, aerospace hardware and communications infrastructure. The minerals that lie beneath the waves are also a crucial ingredient in the power arrays that deliver renewable energy.

How much is down there nobody knows – a mere five per cent of the ocean floor has been explored. What we do know is that we need new sources of these metals and minerals. Cobalt, for instance, is mined on land almost exclusively in the Democratic Republic of Congo, one of the poorest nations in the world, whose people have struggled through decades of civil war, violence and corruption. Other terrestrial resources are becoming harder and harder to mine, while China has been dominating the production of rare-earth minerals, prompting the West to search elsewhere.

Deep sea mining promises so much. Untold riches could be lurking down in the deep, helping to sustain our rapacious appetite for new technologies. The catch? Environmentalists warn that mining the seafloor could destroy fragile marine habitats and further accelerate humanity’s destruction of ocean ecosystems.

Further complicating the issue is our need to divest from fossil fuels. To do so, we’re going to need access to vast quantities of minerals to build the technology that will power our low-carbon future. And for that, Murton says, we have no choice but mine the seafloor. And if it has to happen, he at least wants to make sure it works out for all life on Earth.

Manganese nodules such as these contain copper, cobalt, nickel and other rare metals that are essential for the production of modern electronics. Credit: Caroline Seidel/DPA/PA Images

There are three types of seabed minerals up for grabs: polymetallic nodules (source of nickel, cobalt, copper and manganese), massive sulphides (copper, lead, zinc, gold and silver), and cobalt-rich manganese crusts (cobalt, but also some vanadium, molybdenum, platinum and tellurium, key to thin-film high efficiency photovoltaic cells). Each occurs in distinctly varied habitats, and each requires different technologies to get it above the ocean surface. And each has a different environmental impact.

To find the source of all these metals, you have to go back all the way to the Big Bang. Some of the elements that we know and crave to power our digital world are the result of nuclear reactions that make stars explode as supernovae; others are probably the debris left behind after neutron stars collide.

The holy grail of deep sea mining is usually potato-sized, black and lumpy: polymetallic nodules that take millions of years to gain just a centimetre in size; some are as small as a pea, but others grow as large as a volleyball. They have mainly been found about four to six kilometres beneath the ocean’s surface. One mineral hotspot is an area south of Hawaii and west of Mexico, known as the Clarion-Clipperton Zone (CCZ).

Spread across an abyssal plain covering more than one million square miles, these precious minerals usually just lie on the seabed, covered by a shallow layer of silt that’s five to 15 centimetres thick. The nodules are estimated to contain an average of 32 per cent metal – and could provide hundreds of millions of tonnes of copper, nickel, cobalt, manganese, iron and rare earth elements, a supply that could last us hundreds of years.

To scoop them up, companies are considering a variety of techniques such as hydraulic dredging, a sort of deep sea vacuum for tiny rocks. These nodules are the easiest to mine, and they were the first to spark the interest in deep sea mining. Their discovery led to the UN Convention on the Law of the Sea (UNCLOS) in 1982 and to the founding of the International Seabed Authority (ISA), which oversees mining claims in international waters. Even today, no one really knows or understands the ecosystem around these nodules, in a sediment that’s been undisturbed for thousands of years.

Then there are seafloor massive sulphides (SMS) – deposits that can be several hundreds of metres wide and tens of metres thick. These are formed in hydrothermal vents, colloquially known as black smokers due to their resemblance to chimneys. These structures of metal-rich sulphide precipitated from extremely hot water very rich in minerals, and exist at depths ranging from about 1,600 to 5,000m under the sea.

Usually located between continental plates, for example along the Mid-Atlantic Ridge, the Indian Ocean ridges and in the South West Pacific, they are thought to contain some 30 million tonnes of metal – mostly copper, zinc, lead, gold, and silver. Where the SMS deposits are forming is also home to a very rich unique and unusual fauna: fish, crustaceans, tubeworms, clams, slugs, anemones, shrimp – these bizarre vents are oases at the bottom of the sea.

Finally, there are cobalt-rich ferromanganese crusts of up to a quarter of a metre thick that form on rock surfaces such as seamounts from minerals precipitated from seawater over many millions of years – mostly iron and manganese. They are found one to four kilometres below the surface and are thought to be the hardest to mine.

Credit: Joshua Lambus/Solent News/REX/Shutterstock

Murton’s latest expedition took place in October, when he deployed robotic vehicles sporting new tools and sampling methods to analyse the deep sea mineral deposits. The robots helped him look at crusts of iron and manganese rich in cobalt and studied how they formed over tens of millions of years.

“Assumptions about where to expect to find these types of deposit are simplistic,” says Murton. “Our research shows that there is a sweet spot of geological conditions that must be met for a deposit to form and be preserved. Over millions of years, the geological conditions can change from those favouring formation of the deposit to those that later destroy the deposit.” So to predict resource potential, it’s crucial to first have a thorough grasp of the local geological history of the region where the deposit is formed.

Until now researchers and companies analysed crusts across the entire ocean basin – which doesn’t really help to understand why, how and where they grow – or disappear because of erosion. Cobalt-rich crusts, for example, form at seamounts that are effectively underwater volcanoes. But out of tens of thousands of underwater volcanoes, only about 50 have been explored in detail. There are areas where seamounts don’t have favourable conditions for crusts to form – and understanding how it works should give an indication whether these crusts are commonplace or rare.

A couple of years ago, Murton studied a different part of the ocean floor, in the middle of the Atlantic – and drilled, for the first time ever, into extinct hydrothermal vents, dead for thousands of years. When they were active, hot water escaping from them created deposits of massive sulphides rich in cobalt, gold, zinc and rare-earth minerals. But as the volcanic activity ceased, the vent life disappeared, sea water got in, oxidised the deposits and broke them down, flushing some of the copper away – and making them less valuable.

But what happened next made them interesting again. Beneath the surface, the deposits remain warm for thousands of years and fluids reconcentrate some of the valuable metals. On their surface, the weathered deposits form metal-rich sediments that then fall off and flow downslope a kilometre or so away, collecting into ponds and basins in the surrounding seafloor. There, they can build up thick deposits of sediments with a lot of valuable metals – something that hasn’t been recognised up until now, says Murton. Locating these dead SMS deposits and their metal-rich sediments is tricky though, because they are very small, about the size of a football pitch, and hidden by a layer of normal, chalky marine sediments.

Murton, however, was determined to find them and assess their economic value – because, he says, dead SMS deposits and their metal-rich sediments might be at least ten times more common than the active hydrothermal vents. And mining them would be less damaging to the unique lifeforms that inhabit the active hydrothermal vents.

To find the hidden deposits, the team applied electromagnetic waves and electrical currents to seabed and tried to spot changes in resistivity and inductive potential in the sediment. “By doing this, we found that the deposits are at least 80m thick under the seafloor,” says Murton. And when they started drilling, they were in for a surprise. Previously, it was assumed that such deposits were mainly expressed as seamounts above the surrounding seafloor, says Murton. Just scoop it up, and you’re good to go. That’s not what they found.

Instead, the team discovered that the majority of the resource – almost three times greater than the surface expression – lies at depths down to 200m beneath the deep seamounts. If this is true for all dead SMS deposits, it would mean that much more metal can be extracted from the same location on the seafloor than previously thought, says Murton. “This is obviously better for the environment – disturbing less for more – and it’s better for the industry, which gets a greater yield for the same investment in mineral exploration and environmental assessment.”

Credit: REX/Shutterstock

Regan Drennan cares about worms. Focussing her microscope, in an otherwise empty lab at the Natural History Museum in London, the biologist has a tiny, snowy-white, prickly worm under the lens. It’s probably new to science, she says – found recently roaming the abyssal plains of the tropical central Pacific, the Clarion-Clipperton Zone. Tucked between two fracture zones that plate tectonics have carved in the crust beneath the ocean, its waters are among the clearest on the planet, with fauna unlikely to be adapted to any high sediment concentrations.

This is the area that mineral-hungry mining companies have been eying for decades now. The murky seabed is home not only to worms and an astonishing variety of other marine life, but also to very rich mineral deposits – mainly polymetallic nodules. These nodules are estimated to hold more cobalt, nickel and manganese than the entirety of these resources on land. It’s here that a clutch of companies have already received permits to explore the area for polymetallic nodules, and there’s a queue of more contractors applying for licences.

And it's this area that Drennan is concentrating on. She’s studying the baseline biodiversity of seafloor fauna in the part of the CCZ licensed to UK Seabed Resources, a subsidiary of the US defence contractor Lockheed Martin keen to start mining here (as the US hasn’t ratified the 1982 UNCLOS, American firms themselves can’t apply to the ISA for seafloor-mining licences). “We know so little about these environments that it is almost impossible to predict how they will be impacted – we have no baseline, we can’t know how they will be impacted because we don’t fully know what is there to be impacted in the first place,” says Drennan.

In 2013, an expedition to the eastern CCZ collected 12 animal species – seven of them were new to science. The team also discovered that more than half of all the animals down there used the nodules as surfaces they could attach to. Last year, another group, led by Sergi Taboada, found a new sponge species in the eastern CCZ - and it only lives on nodules.

It’s tricky to understand the impact of mining on these ecosystems, as they are known to have an extremely slow recovery time; think generations to millenia. A recent analysis pooled all available data from various trials on the potential impact on biodiversity and found that the immediate impact of mining is rather severe – both in terms of the density and diversity of most animal groups. And it's unclear what long-term effects would be.

Still, not all deep sea mining is equal. Targeted methods like the ones Murton is researching with his precision drilling into dead vents might not impact biodiversity as much as trawling across the seafloor kicking up sediment. Large sediment plumes from mining would spread out for kilometres, smothering sponges and corals, says Drennan. The plumes would block respiratory and feeding structures and dilute suspended food particles in the water or on the top layer or sediment that many deep sea animals feed on. “The large-scale removal of polymetallic nodules, or the burial of nodules by sediment plumes would also remove the hard substrate habitat that many animals in this ecosystem require to grow or live on,” she adds.

While a single mining operation is unlikely to cause complete extinction of any species, several mining explorations is a different matter, says University of Hawaii oceanographer Craig Smith – and currently 16 permits to explore the CCZ have been granted. “If they all were mined, the total area impacted could be more than 500,000 square kilometres, or an area equivalent to the the size of France. Because abyssal ecosystems recover so slowly, even if takes centuries for all 16 claims to be mined, no mined area will have fully recovered before the last mining begins.”

But they are not mining just yet - and Drennan thinks that researchers have to be really proactive to assess and prevent the damage. “This is a unique point in history where scientists get to assess and study an ecosystem before human activity takes place, so it’s important that we use this opportunity wisely,” she says.

Credit: Joshua Lambus/Solent News/REX/Shutterstock

With a license to explore an area twice the size of Wales, UK Seabed Resources plans to investigate 133,000 square kilometres of the Pacific seafloor in the CCZ for mineral-rich polymetallic nodules. “Once the regulations are in place, commercial-scale mining is likely to start within a decade,” says managing director Chris Williams.

While Williams knows there will be some environmental impact, he thinks it will be low. “No explosives or drilling is required, as the deposits sit on the seafloor surface, and collection methods can be designed to minimise intrusion into the seabed to a few centimetres,” he says. The ore – the nodules – are chemically inert, so the toxicological risk is also very low, he argues. “The risk from environmental accidents is also minimal, as in the event of a system failure, the extracted material simply falls back to the seafloor, from where it came.”

Smith disagrees. “On local scales, mining will reduce biodiversity, very likely for millions of years,” he says. “This is because mining will directly remove manganese nodules, which harbour an obligate diverse fauna, over some 10,000 square km during the expected 15 to 20-year duration of a single mining operation.”

On the other side of the Atlantic in Canada, Toronto-based Nautilus Minerals – with its main shareholders in Russia and Oman – is getting rather impatient. Since 2010, it’s been telling investors, the media and the government of Papua New Guinea that it’s about to start commercial mining operations 30km off the island nation’s New Ireland Province. It wants to mine for gold and copper in the volcanic Solwara 1 area, 1,600m below the surface of the Bismarck Sea.

In 2012, UK-based Soil Machine Dynamics even built three huge autonomous machines for Nautilus, to collect massive sulphide deposits at active hydrothermal vents at Solwara 1. With the press and NGOs following the robots’ every move, Nautilus brought them to Papua New Guinea and in 2017 the machines underwent submerged trials. But then the company hit a snag: the owner of the shipyard in China where Nautilus’s support vessel was supposed to be built cancelled the contract due to a lack of funds – prompting its shares to fall to 7¢; a long time ago, shares traded at more than CA$4 apiece. If the company finds the funds, it hopes to start operations in around 2020.

But someone else might get there first. A Saudi Arabian firm Manafai plans to get zinc, gold and other metals from the bottom of the Red Sea. And a Belgian dredging company DEME’s subsidiary, Global Sea Mineral Resources, is getting ready to test a remotely operated underwater combine harvester dubbed Patania Two (P2) in the CCZ in early 2019. The machine will suck nodules with a special nozzle, but won’t yet send a slurry of nodules to the ship, something that will happen during real commercial operations. DEME and a German research ship funded by the EU will monitor whether the plumes of silt the mining will kick up are bigger than estimated, to assess the impact on the environment.

Also keeping a close watch on such expeditions will be the regulators. Coastal states can lease areas within their national jurisdictions (200 nautical miles) and issue a license. Beyond national jurisdictions, the International Seabed Authority (ISA), founded in 1994 and based in Kingston, Jamaica, is the intergovernmental regulator created to organise, regulate and control all mineral-related activities in the international seabed area. Composed of 168 member states, ISA-issued exploration licences are valid for 15 years and cost $500,000. So far, ISA issued 16 exploration permits for the CCZ, and globally 29.

No commercial mining can occur though until an exploitation license is granted - and so far, there are none because it can only happen once the exploitation regulations are in place. ISA has been drafting and redrafting these regulations - the so-called Mining Code - for years, but aims to finally adopt them in 2020.

While organising and controlling mining, the ISA is also responsible for ensuring the protection of the marine environment from seabed activities. “As no deep seabed mining has occurred yet anywhere in the world, current exploration activities are aimed at gathering the necessary information to enable the assessment of potential impacts on marine biodiversity,” says Michael Lodge, ISA's secretary-general. In 2012, the ISA outlined nine areas in the CCZ where no mining activities may take place.

Credit: REX/Shutterstock

But what if a company doesn’t play by the rules? The ISA is still debating how it will actually police mining activity. Ann Dom, deputy director of Seas At Risk, an NGO that campaigns for the protection of marine environments, fears the worst. “The lack in environmental expertise in the ISA and its un-transparent manner of working leads us to be deeply concerned about the quality of the regulations,” she says.

Scientists have warned repeatedly about the risk of large-scale loss of biodiversity, she adds, “which would be caused by the mining activities itself, as well as the transporting of sediments five kilometres up to the surface to ships.” The mining activities and wastewater are likely to create sometimes toxic sediment plumes that would spread over an area up to 100 km, smothering life on the seabed. Dom also points to a recent collective letter published in Nature Geoscience, where several researchers concluded that most mining-induced loss of biodiversity in the deep sea is likely to last forever on human timescales, given the very slow rates of recovery in affected ecosystems.

Another recent article in Frontiers in Marine Science concludes that the mining industry cannot deliver an outcome where there is no loss of biodiversity, mainly due to a lack of research into deep sea ecosystems and a lack of technological nous needed to minimise damage. In April 2018, several scientists called for a prohibition on mining active hydrothermal vents. And a recent report by the International Union for Nature Conservation concluded that our current understanding of the deep sea does not allow us to effectively protect marine life from mining operations.

And environmentalists don’t buy the argument that deep sea mining may well replace other unethical ways of finding the minerals supporting our unnatural world. Take the cobalt mines in Congo, which are plagued by labour abuse and have previously relied on thousands of child workers. There is no evidence that Congolese mines would close because of deep sea mining, says Dom. “One cannot solve one problem by creating another. Problems with terrestrial mining need to be resolved on land – not extended into the sea. We need to learn to use minerals in a smart and efficient manner and reduce demand. Then we won’t need to dig up the deep sea to fuel a throwaway economy in which metals are turned to waste on a large scale, at the expense of the marine environment.”

But while mining may be a bogeyman, in terms of land-based activities it has one of the smallest footprints – especially compared to agriculture, which is the human activity with the biggest impact on Earth, says James Hein, a scientist at the US Geological Survey. Given that the oceans occupy 71 per cent of the Earth’s surface, mining will indeed only impact a tiny amount of that. It's just like with trees, says Murton: if you cut one from a forest, that’s bad news for that particular tree – but it won’t necessarily have a huge impact on our understanding of the forest. But cut down the whole forest at your peril.

Ultimately, humanity may indeed have a choice: accept some lasting damage to marine life, or give up on the goal of developing the technologies and infrastructure that we need to transition from the fossil-fuel economy to a world powered by green and renewable energy. At that point, both sides of the debate can claim to be “green” and conscious of the environment. Judging who is indeed pushing the most, or least, sustainable option will be a crucial step for life above and below the waves.

By Katia Moskvitch