Deep-sea mining to source metals including nickel, manganese, cobalt and copper could result in one of the largest impacts of any industrial activity on our planet. There is widespread concern about the potential threats to the ecosystems and habitats of the deep if mining is allowed to go ahead. Increasingly urgent questions are being asked about whether deep-sea mining is necessary, desirable, or economically viable.
Deep-sea mining is still in the experimental stage and its possible impacts on the deep ocean remain largely unknown. But existing information and observations from exploratory deep-sea mining are leading scientists to warn that biodiversity loss would be inevitable, extensive, and most likely irreversible. Deep-sea mining would also disturb our planet’s largest carbon sink during the global climate emergency.
There is currently no evidence that the marine environment can be effectively protected from the harmful effects of deep-sea mining. Allowing this destructive new industry to go ahead is therefore inconsistent with the international community’s environmental protection obligations under the United Nations Convention on the Law of the Sea (UNCLOS).
Three types of deep-sea mining are currently envisaged. On the abyssal plains, deep-sea mining targeting polymetallic nodules would involve strip-mining the seabed. Depending on the method employed, this process would remove or disturb the top 6-20 centimeters of the seafloor sediment, leading to the potential extinction of species living on or within it. The nodules themselves support complex ecosystems that would be entirely lost, causing species to go extinct. Each mining operation would effectively devastate 8,000–9,000 square kilometers of deep ocean seabed over a 30-year license period.
Similarly, stripping seamounts of their outer layer of crusts – to extract cobalt and other metals – would destroy critical deep-sea habitat and all life that depends on it, such as deep-sea sponge and cold-water coral ecosystems that can take thousands of years to grow.
Finally, mining hydrothermal vents would destroy habitats and kill the organisms that live there before we have had the chance to study the biodiversity of these unique and fragile ecosystems.
Beyond the immediate direct impacts on mined ecosystems, there would also likely be wider consequences:
- As collector vehicles mine the seafloor, sediments would be resuspended, creating plumes which could disperse over tens to hundreds of kilometers beyond mining sites. These sediment plumes would smother suspension feeders such as cold-water corals and sponges on the seafloor adjacent to mining areas – however, the full potential extent of impacts is unknown as there is limited scientific data on the effect of plumes on individual species and ecosystems.
- The discharge of wastewaters containing seawater, sediment and mine tailings (or mining “fines”) back into the ocean would form mid-water plumes that could travel hundreds of kilometers. These plumes would cloud the water column, would affect filter-feeding organisms, and could introduce toxic concentrations of metals to marine food webs.
- Noise, light pollution and sediment plumes could seriously impact species – including whales – that use sound, echolocation or bioluminescence to communicate, find prey and escape predators.
- Marine sediments are a huge and globally important carbon store, with much of this carbon locked away in the deep sea where it can remain for millenia. Deep-sea mining could disrupt the natural processes that transport carbon from the surface to the seafloor, and disturb carbon-rich sediments, impacting the deep sea’s role in ocean carbon cycling and storage.
Deep-sea mining is also expensive. Although it may one day be profitable to individual companies (all currently registered in the Global North), questions are being raised about deep-sea mining’s wider economic benefits and to whom they would accrue. The International Seabed Authority (ISA) is required under UNCLOS to ensure that the exploration and exploitation of international areas of the ocean “be carried out for the benefit of (hu)mankind as a whole.” That means the ISA should only license mining in areas of the seabed beyond national jurisdiction if it will benefit humankind. However, recent calculations suggest that the annual royalties that would be collected by the ISA for each mining license would only amount to a few hundred thousand US dollars for each ISA Member State. Much of the wealth would go into the pockets of mining companies. Deep-sea mining is a risky business. Some analysts are warning that it is also a bad investment based on dubious economics. Papua New Guinea lost over US$ 100 million of its investment in deep-sea mining in its national waters. The government of Papua New Guinea is now concerned about the environmental implications of deep-sea mining, and in 2019 it called for a moratorium on deep-sea mining in its own waters.
Due to the risk of irreversible ecosystem loss and the destruction of invaluable carbon storage, in June 2022 the UN Environment Programme’s Finance Initiative (UNEP-FI) published a briefing paper stating that the financing of deep-sea mining activities is not consistent with the Sustainable Blue Economy Finance Principles. Mounting concerns about the environmental and financial risks associated with deep-sea mining have led to a growing number of businesses, banks and financial institutions to opt out of investing in the industry, and instead joining the call for a moratorium.
Deep-sea mining poses a threat to communities who rely on a healthy ocean, not only for their livelihoods and immediate survival, but also due to a deep spiritual and cultural connection. Indigenous Peoples across the Pacific Ocean, for example, sustain a different relationship with the natural world from that of the West and see the deep sea as a sacred place for creation. The deep sea illustrates and explains the histories and cultures of those before us. The potential destruction of tangible and intangible cultural heritage by deep-sea mining continues an ongoing legacy of colonialism, through cultural erasure and the continuous drive for profit from imperial powers.
To find out more about the governments and other stakeholders calling for a moratorium, click here.