An underwater photograph of black potato-sized polymetallic nodules scattered on the seafloor
Black, potato-sized polymetallic nodules scattered on the seafloor are drawing prospectors for their cobalt, nickel, copper, and manganese. Credit: 2019 Southeastern U.S. Deep-sea Explora-tion/Office of Ocean Exploration and Research/NOAA

Nauru, the smallest island nation in the world, invoked a legal provision last June that started a countdown clock for deep-sea mining in international waters. The move is essentially an ultimatum to speed up the completion of deep-sea mining regulations so that commercial enterprises can begin exploiting the seabed.

In a letter to the president of the council of the International Seabed Authority (ISA), the United Nations (U.N.) body that oversees mining in international waters, Nauru president Lionel Aingimea stressed the “urgency” of finalizing regulations so that industry can move forward.

The prospect of mining in the deep sea has attracted criticism because of the damage it could inflict on marine ecosystems. Supporters, however, claim it is less harmful than terrestrial mining and necessary to supply materials for renewable technologies, such as lithium-ion batteries for electric vehicles.

Ethical questions about scientists funded by corporate dollars plague the nascent industry.

ISA has been deliberating regulations governing commercial mining of the deep seafloor, called the Mining Code, since 2014 and planned to finish them in 2020, but the COVID-19 pandemic sidelined the process. The “2-year rule” that Nauru triggered compels ISA to finalize the rules by mid-2023. If it doesn’t, ISA may accept applications for exploitation even in the absence of formal guidelines, with many questions about the long-term effects of mining likely still unresolved.

The deep sea is the largest habitat on Earth. Still, we know very little about it. ISA has issued 31 exploration contracts to companies interested in conducting baseline studies. Data from these studies have fueled basic science in the deep sea—one deep-sea mining company, UK Seabed Resources, even keeps a list of research that grew from its environmental surveys.

Until commercial exploitation permits are issued, however, mining will remain illegal in international waters.

In the meantime, public scrutiny of ISA’s governance plagues the nascent industry. Scientists and international organizations have voiced criticism about the scope of scientific oversight of ISA’s various projects and technologies, and observers have drawn attention to the ethics of scientists funded by corporate dollars.

Cobbles on the Seafloor

Deep-sea mining targets rare earth elements (REEs) and other metals and minerals thousands of meters below the ocean surface. Three types of resources have caught the eyes of prospectors.

These nodules from the Cook Islands in the South Pacific Ocean come in many shapes and sizes. Credit: USGS

The first, seafloor massive sulfide (SMS) deposits, precipitate around hydrothermal vents as they emit sulfide-rich fluids into seawater. SMS deposits are rich in copper, gold, silver, REEs, and zinc. The second resource considered for deep-sea mining is a type of rocky crust that coats seamounts. The coating, which precipitates over millions of years, is rich in iron, manganese, and cobalt and can be up to 26 centimeters thick. The third mineral resource is polymetallic nodules, sometimes called manganese nodules after their most abundant metal.

Most countries, including Nauru, are interested in mining these nodules, which don’t require drilling to collect. The dark, potato-sized mineral masses, or concretions, form slowly by the precipitation of metals from seawater and the sediment underneath. They grow several millimeters every million years and sit on the seafloor like “cobbles on a street,” said Diva Amon, a marine biologist and director of SpeSeas, a nongovernmental organization in Trinidad and Tobago.

Although the nodules appear in various places around the deep ocean, the primary target of potential mining is the Pacific’s Clarion-Clipperton Zone (CCZ), a 5,000-kilometer stretch of seafloor between Hawaii and California that extends 4,000–5,500 meters deep. The CCZ hosts trillions of mineral-rich nodules.

The Clarion-Clipperton Zone spans approximately 4,500,000 square kilometers. Credit: Horizon, CC BY 4.0

Reaching the nodules involves a three-stage process: First, a support ship lowers a remotely operated vehicle to the seafloor. Next, the vehicle—like a Roomba vacuum for seafloor mining—drives around through the soft sediments scooping up nodules. Last, a large pipe sucks the nodules to the ship above. Cobalt, copper, iron, manganese, and nickel can then be extracted from the nodules during onshore processing and refining.

A dozen European and Asian countries and several island nations have sponsored companies for exploration permits so far. The United States cannot apply for permitting through ISA because it has not ratified the treaty that presides over it, the U.N. Convention on the Law of the Sea. However, a subsidiary of the U.K. arm of the American company Lockheed Martin, UK Seabed Resources, has two permits for exploratory mining.

In early 2021, the Belgian company Global Sea Mineral Resources (GSR) and the German Federal Institute for Geosciences and Natural Resources (BGR) ran a test in the CCZ with a one fourth–scale 25-metric-ton prototype mining vehicle named Patania II. It was the first mining trial of any kind in the CCZ since the late 1970s, when commercial interest first flared for deep-sea mining during a metal market crunch.

“It was by far the most extensive suite of monitoring equipment for any trial that’s ever taken place.”

Independent scientists, funded by European public science agencies, observed the trial by placing more than a hundred sensors around the simulated mining activities. “It was by far the most extensive suite of monitoring equipment for any trial that’s ever taken place for deep-sea mining technologies,” said Massachusetts Institute of Technology’s Thomas Peacock, a physical oceanographer who attached a novel deep-sea sediment-monitoring sensor to Patania II.

As the industry gathers speed, opponents are sounding the alarm.

More than 600 scientists and policy experts from more than 44 countries have signed a petition calling for a ban on deep-sea mining “until sufficient and robust scientific information has been obtained.” And the Patania II expedition was observed by protestors on board the Greenpeace ship Rainbow Warrior III.

Separately, BMW, Google, Samsung, and Volvo signed a call from the World Wildlife Fund for a temporary ban on deep-sea mining. The companies promised to keep deep-sea minerals—which are not currently commercially available—out of their products, supply chains, and financial activities.

The Possible Toll of Mining

Opponents of deep-sea mining say that without a better understanding of its consequences, the risk of environmental damage it poses to the seafloor could be too great. Although research into the effects of mining on deep-sea ecosystems is scarce, one significant attempt to simulate the long-term effects uncovered some damning clues.

In 1989, German scientist Hjalmar Thiel led a test of deep-sea mining off the coast of Peru. The expedition, funded by West Germany’s Ministry of Science and Technology, towed an 8-meter-wide plow harrow on 78 passes through an 11-square-kilometer section of seafloor. The plow disturbed the sediment enough to bury most of the nodules—simulating their removal by mining.

Twenty-six years after a simulated mining test, scientists found long-lasting damage on the seafloor.

Twenty-six years later, scientists on the R/V Sonne visited the site for the first time in decades and found long-lasting damage, said ecologist Erik Simon-Lledó from the National Oceanography Centre in the United Kingdom.

The nodules still sat under a blanket of sediment, and the critters that usually live among the nodules hadn’t returned. “Nodules act like trees in a forest,” said Simon-Lledó. “If there are no trees, there are no squirrels.”

In other research, a group in the Netherlands and Germany simulated the deep-sea food web and showed that removing the nodules resulted in a 31% loss of links in the ecosystem’s food chains.

The deep ocean is so poorly understood that in a 30- x 30-kilometer area on the seafloor, a typical research survey might identify hundreds of species living on the nodules themselves—and likely between 70% and 90% would be new to science, Amon said. That doesn’t include the multitudes of single-celled organisms living there.

Deep-sea mining could potentially kill microbes in the seabed that sequester carbon dioxide and trigger the release of carbon dioxide stored in deep-sea sediments.

ISA has marked off 1.6 million square kilometers of sensitive areas within the CCZ from mining.

Moreover, many marine animals use sound to avoid predators or find prey, and loud noises from deep-sea mining could impair them, said oceanographer Craig R. Smith from the University of Hawai‘i.

“Just like you and I get on with our jobs every day, every species in the deep ocean has this role that it plays,” Amon said. These jobs are “all linked to services that you and I rely on,” like drawing carbon out of the atmosphere, storing heat, and supporting fisheries.

To safeguard vulnerable ecosystems, ISA excluded 1.6 million square kilometers of the CCZ from mining, singling out areas for their biodiversity and the presence of seafloor features like seamounts.

Simon-Lledó believes that the biggest open question about deep-sea mining relates to the effects of sediment kicked up during the extraction process. Mining vehicles will muck up bottom waters with fine particles as they roam around sucking up nodules, and operators will discharge sediment carried up in pipes back into the ocean.

Muddy water could clog delicate mucus filters of animals like the giant anemone Relicanthus sp. or obscure light that species like the vampire squid Vampyroteuthis infernalis and the barbeled dragon fish Idiacanthus antrostomus use to mate and hunt. The bottom waters of the CCZ are some of the clearest in the world; sediment collects on the seafloor at only a few millimeters per millennium.

Sea cucumbers, brittle stars, worms, and wispy new species related to jellyfish and coral make their home in deep-sea nodule fields. Credit: DeepCCZ expedition

In one modeling study, researchers calculated that a cloud of sediment could travel a maximum of 4–9 kilometers from a study site depending on deep-sea currents. Data from the GSR test with Patania II could provide much-needed field observations.

“There could be very grave consequences for these activities,” said Amon, who signed the petition for a moratorium on deep-sea mining. Amon worked on baseline surveys for UK Seabed Resources between 2013 and 2016. “I think we as scientists have a responsibility to connect the dots between our research and informing policymakers, decisionmakers, and, ultimately, humankind,” she said.

“I have mixed feelings about the moratorium,” said Smith, who has also worked with UK Seabed Resources in the past. Smith has not signed the petition and worries that the moratorium doesn’t detail specific research goals for tackling mining impacts or the resources needed to achieve those goals. Because research into the deep sea and mining effects is often funded by private companies and governments keen on mining, he believes research could plummet if a moratorium is enacted.

One scientist was reportedly at risk of losing his funding after commenting negatively about deep-sea mining.

Simon-Lledó, who did not sign the petition, thinks that scientists must only inform others. “As researchers, we have the obligation to provide clear, unbiased information so that an open debate can be held on whether deep-sea mining should go ahead or not.” Simon-Lledó’s employer, the National Oceanography Centre, has received funds from industry partners, including deep-sea mining companies.

More than half of deep-sea biologists have worked with mining companies or governments for research, biological oceanographer Lisa Levin from the Scripps Institution of Oceanography told Mongabay in 2021. Financial support sometimes comes with nondisclosure agreements and can raise ethical questions about scientific independence. Jeff Drazen, an oceanographer at the University of Hawai‘i, was reportedly at risk of losing his funding after commenting negatively about deep-sea mining, according to the Wall Street Journal. Drazen declined to comment on the matter for this article.

Two of the leading mining companies are taking different approaches when talking publicly about potential environmental harm.

GSR managing director Kris van Nijen told Reuters last year that “GSR will only apply for a mining contract if the science shows that, from an environmental and social perspective, deep seabed minerals have advantages over the alternative—which is to rely solely on new and current mines on land.”

Chief executive officer of The Metals Company, Gerard Barron, on the other hand, has called the abyssal plain a “lifeless desert” where the effect of mining would be minimal.

Prospecting Mining’s Potential

Mining companies say the solution to global warming can be found on the seafloor.

Although major mining companies have different takes on the possible environmental damage of mining, they promote a shared vision of the industry as an answer to climate change: “The biggest risk to the ocean right now is global warming,” van Nijen told Time. Barron calls the nodules “a battery in a rock” and “the easiest way to solve climate change.”

Unlike most land-based ores, nodules on the seafloor contain several valuable minerals in one package and produce better yields overall. Rich with cobalt and nickel, nodules could supply metals for batteries used to power today’s electric vehicles and energy technologies.

A widely cited study by the World Bank and the International Energy Agency estimated that global demand for cobalt will increase by more than 450% by 2050 if the world adopts green technology to cut fossil fuels and limit warming to 2°C. Demand will shoot up by more than 50% for nickel over the same time frame and by 100% for copper.

Mineral economist Ian Lange from the Colorado School of Mines said that the World Bank’s analysis involves simplified projections, however, because it assumes that technologies like batteries won’t change over time. Battery technologies are evolving to use cheaper metals in place of cobalt, for instance.

However accurate these estimates turn out to be, supporters of deep-sea mining claim that these operations will be more environmentally responsible than those on land.

“I am confident we will be able to show that extracting polymetallic nodules will have a lower impact on the environment than will be the case with the opening of new mines on land or the expansion of existing ones,” Chris Williams, managing director of UK Seabed Resources, told the Guardian.

Several groups of researchers are now trying to test that claim.

Two dozen experts in sea- and land-based mining have joined together to begin comparing the two types of operations using common metrics, like biodiversity loss and toxicology. The group was convened in 2020 by the New York–based biologic science nonprofit Cold Spring Harbor Laboratory.

“What’s driving us is just the discourse about the idea of deep-sea mining going ahead based on assumptions that may not be supportable,” said Verena Tunnicliffe, a deep-sea biologist at the University of Victoria who co-organized the group. Tunnicliffe said she has never been supported by industry funds, but some members of the group have worked with mining companies.

Although the research is ongoing, comparing the two operations is complicated because of the lack of data from the deep sea, she said. “There are people in the group that are beginning to feel that it’s just not possible to do a credible job.”

Separately, energy and environmental researcher Saleem H. Ali from the University of Delaware has collaborated with industry and ocean health experts to investigate mining on land versus at sea. When it comes to the carbon footprint, the amount of waste generated, and the social impacts, deep-sea mining is a better option than terrestrial mining, said Ali.

“The carbon footprint of deep-sea mining is far less than terrestrial mining,” Ali said. “In the case of nickel, it’s about 80%. For cobalt, it’s still about 30% less.” The Metals Company’s head of strategy and business development also participated in the research.

Murky Waters

Nauru’s 2-year ultimatum gives experts very little time to answer outstanding questions about the safety and benefits of deep-sea mining. When the countdown reaches zero in mid-2023, ISA is supposed to be prepared to properly evaluate permit requests, including having a framework for environmental impact surveys.

Pradeep Arjan Singh, a doctoral candidate at the University of Bremen, said that the Mining Code has a long list of unresolved issues and principal among them is the question of sharing income. Per the U.N. Convention on the Law of the Sea, the international seabed and its mineral resources are the “common heritage of mankind.”

Under one interpretation, all member parties of ISA (167 countries plus the European Union) stand to get some cut of the profits from seabed exploitation. This is uncharted ground for international negotiations, however. Although fishing and whaling treaties have divvied up global ocean resources, they’ve never required shared revenue like this before. (Simultaneous discussions are underway about whether marine genetic resources, or marine biodiversity, qualify as the heritage of humankind.)

“The consequences of the council not being able to meet the deadline are something that we need to speak about.

ISA’s council, which is responsible for finalizing the Mining Code, has declined to meet virtually and instead postponed all discussions until members can meet in person.

“It’s quite a crucial question on how the council is actually going to do all that with what’s left of these 2 years,” said Singh, who guessed that negotiations on the text of the Mining Code wouldn’t resume until later this year. “We’re losing time.”

Singh said he hopes that members of ISA consider restarting the clock or circumventing the countdown deadline, given the disruption of the pandemic saying, “the consequences of the council not being able to meet the deadline are something that we need to speak about.”

Author Information

Jenessa Duncombe (@jrdscience), Staff Writer

Citation: Duncombe, J. (2022), The 2-year countdown to deep-sea mining, Eos, 103, https://doi.org/10.1029/2022EO220040. Published on 24 January 2022.
Text © 2022. The authors. CC BY-NC-ND 3.0
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