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Deep-sea mining: Climate action with environmental costs

January 10, 2024

Norway looks set to be the first country to allow the mining of rare earths and metals from its ocean floor. How will it work, and what are the risks?

Jelly fish in the ocean
Marine life such as jellyfish are threatened by deep-sea miningImage: Kim Jens Bauer/PantherMedia/IMAGO

In the mid-19th century, science fiction author Jules Verne wrote of precious metals lying thousands of meters underwater.  

"In the depths of the ocean, there are mines of zinc, iron, silver and gold that would be quite easy to exploit," stated Captain Nemo in Verne's classic adventure tale, "20,000 Leagues Under the Sea."

The author was right about the potential raw materials. He was wrong, however, to assume that the minerals could be easily exploited.

Currently, there is no internationally agreed code for mining under the ocean, and the prospect of doing so has attracted huge pushback from campaigners and even corporations due to the massive environmental impact. 

Despite this, Norway made the decision this week to open up 280,000 square kilometers of its national waters — an area greater than the size of the UK — for companies to apply to mine the valuable resources on the ocean floor. The move takes the country closer to being the first to make commercial deep-sea mining happen.

In November last year, over 100 EU MEPs wrote a letter to the Norwegian parliament urging them to reject the proposal due to the environmental risks deep sea mining poses, including to marine biodiversity.  

"The deep sea is a trove of biodiversity, rich in living resources used in medicines and critical in regulating the climate and providing spawning and feeding grounds for fish," said Diva Amon, a Caribbean marine biologist and adviser to the Benioff Ocean Initiative at the University of California. "The planet would not be the same without it."

Cross-section of a polymetalic deep sea nodule rich in Manganese and Cobalt that is targeted for mining
Polymetalic deep-sea nodules rich in valuable metals like manganese and cobalt, seen here in a cross section, are targeted for miningImage: Nature Picture Library/IMAGO

Demand rising fast for metals powering energy transition

Whether copper or nickel for batteries, cobalt for electric cars or manganese for steel production, rare earth minerals and metals are fundamental to the renewable energy technologies driving the world's energy transition. 

But while demand is rising fast, the resources are also becoming scarcer globally. 

According to estimates, in just three years the world will need twice as much lithium and 70% more cobalt. 

And this is despite the slow progress of the energy transition. According to the International Energy Agency, if climate goals were properly pursued through the massive expansion of renewable energy, about five times as much lithium and four times as much cobalt would be needed by 2030.

The projected production volumes for these raw materials fall far short of demand. To close this gap, some countries and companies now want to mine the resources in the deep sea. 

Seabed holds valuable manganese nodules

So-called polymetallic nodules, also known as manganese nodules, are driving the rush to mine seabeds. These potato-sized lumps contain high proportions of nickel, copper, manganese, rare earths and other valuable metals. 

The best-studied area is currently the seabed at between 3,500 and 5,500 meters [between 11,500 feet and 18,000 feet] in the Clarion-Clipperton Zone in the eastern Pacific Ocean near the US state of Hawaii. Spanning thousands of kilometers, the area contains more nickel, manganese and cobalt than any known area on land. 

Can deep-sea mining of manganese nodules be eco-friendly?

The basin in the central Indian Ocean and the seabed off the Cook Islands, Kiribati atolls and French Polynesia in the South Pacific are also of interest for potential extraction.

"The nodules' composition happens to be remarkably well-aligned with the needs of electric vehicle makers," said Gerard Barron, CEO of The Metals Company. "Carmakers will need a great deal more of these metals in order to make battery cathodes and electrical connectors for an electric vehicle fleet of around a billion cars and trucks by mid-century." 

The Canada-based company specializes in the medium and long-term exploitation of mineral resources in the Clarion-Clipperton Zone. 

Although manganese nodules are not yet being mined anywhere in the world, that could soon change as they practically lie directly on the seabed and can be easily extracted without breaking up rock layers or eroding the seabed.  

Automated mining endangers marine life 

Seabed mining is made easy when a huge vacuum can simply travel over the ocean floor to suck up the nodules — which are then brought to the surface with a hose. 

But the living part of the seabed is destroyed along with the nodules, said Matthias Haeckel, a scientist at the Helmholtz Center for Ocean Research in Kiel, Germany. 

"That means all organisms, bacteria and higher organisms that live in and on the sediment and on the nodules are completely sucked in," he said. 

These organisms also require manganese nodules to survive, meaning they "won't come back for millions of years," said Sabine Gollner, senior scientist at the Royal Netherlands Institute for Sea Research. 

Rapid regeneration is impossible because it can take a million years for a nodule to grow a few millimeters.

Deep-sea mining — blessing or curse?

Scientists and opponents of deep-sea mining also fear that the clouds of sediment from the suction could cause enormous damage to ecosystems within a radius of several hundred kilometers.

Potential victims would include plants, creatures in the middle water depths and microorganisms whose respiratory tracts could be blocked by the sediment.

Striking a better environmental balance

The Metals Company aims to mine the nodules in the Clarion-Clipperton Zone and makes no secret of the possible damage to marine biodiversity. 

However, the company has argued that deep-sea mining could be less damaging to the environment than extraction on land, pointing out that it would emit 80% less greenhouse gas emissions.

The company claims deep-sea mining would barely impact carbon reservoirs such as forests and soils, would not displace people, would use less fresh water and release fewer toxins.

The Metals Company has also claimed that deep-sea mining would be largely automated, avoiding the exploitation of cobalt miners, including children, in Congo, where most of the world's cobalt is mined today.

A deep-sea mining vessel moored in the ocean
This drilling vessel owned by The Metals Company is the first to be equipped for deep-sea mining Image: Jochen Tack/picture alliance

Are regulations on the horizon?

Possible exploitation of deep-sea deposits is regulated by the International Seabed Authority, which was established under the UN Convention on the Law of the Sea. It has awarded 31 exploration contracts so far worldwide, but none for commercial mining activities - although it did decide last year that companies could apply to mine the ocean floor. 

These permits allow companies to explore the resources and potential for future extraction, but also require them to collect data for environmental analysis.  

 The Jamaica-based authority has been working on rules on whether, how and where deep-sea mining could be possible. The hope is that it will finalize a code at a meeting later this year so deep-sea mining applications can be adjudicated around robust rules that protect the environment.  

The Pacific island state of Nauru has been collaborating with The Metals Company to accelerate the development of a code so applications can be decided. But other island nations have called for a moratorium on deep-sea mining

"Deep-sea mining would go beyond harming the seabed and have a wider impact on fish populations, marine mammals and the essential function of the deep-sea ecosystems in regulating the climate," Vanuatu's representative, Sylvain Kalsakau, said during the negotiations.

For marine biologist Gollner, there is still a lack of sufficient data to support environmentally friendly underwater mining. "Based on the current data situation, deep-sea mining cannot be managed in a way that would not be harmful to the environment," she said.

She has called for a moratorium based on the data, saying "now would be too early."

Corporations including BMW, Volkswagen, Google, Philips and Samsung SDI have joined a call for a moratorium launched by the wildlife conservation organization WWF, pledging not to use raw materials from the deep seabed or finance deep-sea mining for the time being.

"It's great to see how the deep ocean has inspired support from people and voices across the world," said marine biologist Amon. "Hopefully this momentum for a pause will only keep growing."

This article was originally published in German on April 4, 2023. It was updated on January 10, 2024 to include the announcement that Norway will open its ocean floor to exploration. Stuart Braun contributed to reporting.