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Oceans of minerals

In Jules Verne’s 19th century novel, a submarine travels 20,000 leagues under the oceans, and its crew members are engaged in a range of adventures. Contrary to many perceptions, the 20,000 leagues in question was a measurement of distance rather than depth.

Today, a hot-button environmental issue is deep-sea mining, a type of marine mineral recovery that has morphed over the past few decades from science fiction into a viable industry ready to begin operations, using a very different type of underwater craft to the one imagined by Verne.

Although the primary driver behind the push for this mining is the shift toward a mineral-hungry clean energy economy, deep-sea mining is opposed by environmental groups and many marine scientists, who see significant ecological damage from deep-sea mining as a real risk, especially when so little is understood about life in the ocean depths.

Terrestrial mining is associated with a number of issues, including profligate water usage, toxic chemicals, biodiversity loss, deforestation, copious energy usage and human rights abuses such as the widespread use of child labour for cobalt mining in the Democratic Republic of Congo. Such issues are sometimes raised in order to argue that deep-sea mining is comparatively more ethical, but in reality it is unlikely to become an either/or proposition.

On the ocean floor

Three different types of deep-sea mining are being investigated:

  • Polymetallic nodules are mineral-rich potato-sized lumps that occur in vast quantities on the ocean floor. They are found on abyssal plains, of which the largest is the Clarion–Clipperton Zone (CCZ) in the Pacific Ocean between Hawaii and Mexico. Found at a depth of 3.5 to 6 kilometres, these nodules are rich in manganese, iron, nickel, cobalt, copper, zinc, lead, gold, silver and rare earths among others. Most of the industry’s focus is on these nodules, and some exploratory non-commercial mining is taking place.
  • Hydrothermal vents are places on the ocean floor where heated seawater passes through fissures in the earth’s crust, is exposed to liquid magma and recirculates back to the ocean in a heated state via what look like smoking chimneys. These vents occur at up to 5 kilometres depth, along tectonic plate boundaries. Huge mineral deposits are formed in their vicinity that are rich in copper, gold, lead, zinc and silver.
  • Cobalt-rich crusts are at depths of 600 metres to 7 kilometres, on the sides of seamounts, and are rich in cobalt, titanium, tellurium, nickel, manganese, platinum and some rare earth elements.

Kilometres beneath the ocean surface, the environment is unfamiliar and inhospitable. It is pitch black, and the extreme pressure makes it impossible using current technology for a human to survive. Nodule harvesting usually involves unmanned and robotic harvesting machines similar to bulldozers that are normally driven along the ocean floor. Nodules are pumped up to a ship on the surface, where they are separated from unwanted material, which is dumped. A final part of the chain involves onshore metal refineries.

Environmental concerns

Nodule fields are rich in marine biodiversity, and some animals depend on the nodules themselves for survival. One study by the UK’s Natural History Museum identified more than 5000 species in the CCZ, with 90 per cent unknown to science. This information was compiled by going through scientific studies and databases. Hydrothermal vents in particular are biodiversity hotspots, which has raised questions about the damage that mining would likely cause. The scaly-foot snail that lives near hydrothermal vents on the ocean floor east of Madagascar is the first animal to be declared endangered as a result of the prospect of mining in the deep oceans.

Disturbance of the seabed is liable to generate raised plumes of silt and sand, and these could include toxins such as mercury. There has been some speculation about how far the plumes are likely to travel from their point of origin. A 2022 study in the journal Scientific Advances tracked a “pre-prototype” small collector vehicle and found that the plumes remained within two metres elevation above the ocean floor. Other tests in the central Pacific found sediment spreading outward horizontally up to 300 metres from the mining site, with very dilute concentrations towards the edge of this range. Marine life that comes in contact with the plumes could be harmed, especially filter feeders such as mussels.

Industry messaging has promoted the notion of minimising environmental harm by techniques such as digging down into the ocean bed no more than a few centimetres. One company called Impossible Metals is going one step further, hypothesising relatively large autonomous craft that would float above the ocean floor, each with hundreds of robotic arms that can spot, reach down and pick up a nodule. These would have the ability to identify whether each nodule contains marine life, and if it is found, avoid picking the nodule up. However, for now these collectors are still at an early stage of development.

A likely bigger threat than the plumes stirred up on the ocean floor is the potential damage caused by sediment discharged into the ocean from ships at the surface. These “dewatering plumes” have been likened to underwater dust storms and could be carried up to 1000 kilometres or more by the ocean currents before settling. Scientists recommend that discharging at the bottom of the ocean would be a far better outcome. A 2023 leaked video showed sediment being released into the water by a ship owned by Canadian deep-sea miner The Metals Company (TMC). This was an accidental release that occurred during a test.

Water is an extremely good conductor of sound, and a 2022 study in the journal Science found that one deep-sea mining activity could raise noise levels up to 500 kilometres away. Effects of sound on the deep ocean ecosystem are very little known. Light from underwater harvesting vehicles could also cause harm, such as retina damage, to some organisms adapted to very low light levels.

Activists and critical voices

Environment groups are unified in calling for either a ban or a moratorium on the practice. These include:

  • Greenpeace, including Greenpeace Aotearoa.
  • World Wildlife Fund.
  • Deep Sea Mining Campaign. This focused group is pursuing a corporate divestment strategy and a parallel insurance-targeting strategy. Because deep-sea mining carries risks that are very hard to quantify, it is a natural area for the insurance giants to avoid.
  • Pacific Blue Line.
  • MiningWatch Canada, a group that is paying particular attention to the activities of TMC.

Additionally, 765 marine scientists and policy experts from 44 countries have backed a statement calling for a pause on deep-sea mining until the extent of the associated environmental risks are known, in order for damage to be minimised. David Attenborough has been a high-profile voice against deep-sea mining, calling for a “precautionary pause”. The Pope has also expressed concern, without going into specifics.

The missing regulatory framework

In international waters, this issue is overseen by the International Seabed Authority (ISA), an independent UN-affiliated body. Formed in 1994, it is headquartered in Jamaica, and has 167 member states plus the EU. Until recently, it received little attention, but in the last couple of years it has come under the international spotlight.

Mining companies’ projects in international waters require sponsoring governments. In 2021, Nauru triggered a requirement for a mining code to be created by July 9, 2023. From that date, commercial mining applications can be accepted, although under ISA rules no commercial mining can take place until 2026 at the earliest.

The ISA is in a conflicted position, where it receives a US$500,000 payment for each exploration licence while also being the regulator. It has been accused of having a pro-mining bias and being too closely aligned with the miners. Countries have on occasion criticised the ISA for not requiring sufficiently thorough environmental assessments. ISA secretary-general Michael Lodge once appeared in a promotional video for TMC, when it was known as DeepGreen Metals.

Outside international waters, the remaining territory consists of national exclusive economic zones (EEZs) that extend 200 nautical miles (370 kilometres) from the coasts, plus outlying islands. Here countries have free rein to decide what happens, and they can apply to extend their EEZs for strategic purposes.

Support and opposition

Among international proponents, the most attention has been given to Nauru, a tiny island in the western Pacific, most well known in Australia for its role in immigration detention. Its proposed project involves a subsidiary of TMC called Nauru Ocean Resources. Nauru’s plans are opposed by seven Pacific Island nations.

The Cook Islands, also in the Pacific, have the world’s fourth-largest supply of polymetallic nodules, and in 2022 the country’s Seabed Minerals Authority granted three exploration licences for nodules within its own economic zone. Concerns have been raised because the country’s waters are an important breeding ground for humpback whales.

An increasing number of countries, from diverse parts of the world, are opposed to deep-sea mining, and support either a ban or a moratorium. Both Australia and New Zealand take a similar position to one another, opposing deep-sea mining in international waters unless strong environmental regulations are in place. However, both have resisted activist calls to support an unconditional moratorium. New Zealand has drawn up a regulatory framework for deep-sea mining within its own EEZ. In Australia, this form of mining has been permanently banned in Northern Territory waters.

The consumer end

Minerals yielded by deep-sea mining, especially the polymetallic nodules, are frequently those used in electronics, and the fast-growing renewable energy sector. In its report The Role of Critical Minerals in Clean Energy Transitions, the International Energy Agency (IEA) highlighted future exponential growth in mineral demand to serve the renewables revolution. Under its “sustainable development scenario” it predicted a 19- to 42-fold increase in production for lithium, graphite, cobalt and nickel between 2020 and 2040. The IEA also warned of a “looming mismatch” between demand and future supply.

Unsurprisingly, the deep-sea mineral industry is pushing the message of future supply shortages as a PR strategy. An association with green technology may help soften up public opinion against contentious deep-sea practices, with the implication that the only alternative may be a fossil-fuelled climate disaster. In the clean energy sector, the electric car industry is among the fastest-growing sources of mineral demand, and it is hard to predict whether deep-sea mining will eventually be necessary in order to ensure its continued growth at present rates.

The link between electric cars and seabed minerals is most clear in Norway, world leader for EV market share, where more than 90 per cent of new car sales are plug-in electric. To its north, Norway is eyeing a 329,000 square kilometre area of the Norwegian Sea, roughly the size of Germany, for minerals including rare earths.

A number of companies have publicly come out against deep-sea minerals by joining a sign-on statement from the group Deep Sea Conservation Coalition and committing to exclude them from their supply chains. These corporations include Samsung, Google, Philips, battery makers Freyr and Northvolt, and among the car companies, Volvo, Volkswagen, Scania and BMW.

Curbing demand

When extrapolating the future, it is possible to overlook some less-obvious alternatives, and while they fall short of being stand-alone solutions, they may each be able to tweak demand in a downward direction.

Recycling is an important element, despite its structural inability to keep up with exponentially growing materials demand. A significant issue is the limited proportion of metals being recovered from e-waste. At present, the recovery of lithium is uncommon, and a technological breakthrough is needed to make it cost-effective. Encouragingly, e-waste recycling, applying to every electrical item with a power cord, is mandatory in Victoria. Defunct solar panels can be recycled in Australia via a company called Reclaim PV, on a pay-to-recycle basis.

A future dominated by EVs is still a car-dominated world. Europe is showing the way by designing cities for the benefit of active transport such pedestrians and cyclists. Designing EVs to last longer would help, and ideally the falling cost of batteries will encourage the purchase of a replacement battery for a 10-year-old car rather than a replacement car. More radical is the degrowth-oriented idea suggested by Martin Brueckner from Murdoch University of sharing EVs as an alternative to ownership.

In the meantime, concerned people can follow developments, get involved with the various activist groups, sign petitions and write letters. However, with exceptions such as industrial-sized battery storage facilities, ultimately consumerism, driven by economic growth, is either driving the push for deep-sea mining or providing cover for it to take place.


The Metals Company (TMC) metals.co.

Impossible Metals impossiblemetals.com.

Deep Sea Mining Campaign dsm-campaign.org.

Pacific Blue Line pacificblueline.org.

Article Featured in WellBeing 207 

Martin Oliver

Martin Oliver

Martin Oliver writes for several Australian holistic publications including WellBeing on a range of topics, including environmental issues. He believes that the world is going through a major transition and he is keen to help birth a peaceful, cooperative and sustainable reality.

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