According to the International Energy Agency (IEA), a transition to net-zero globally by 2050 would require six times more mineral inputs by 2040 compared to today. Polymetallic nodules on the deep-seafloor, rich in critical metals like manganese and cobalt - essential for green technologies like electric car batteries - have been touted as a potential lifeline to meet this surging demand.
Yet, despite the promise of these nodules, no commercial deep-sea mining operations have commenced.
Regulatory uncertainty remains the primary obstacle, because no comprehensive international framework yet exists to govern the practice beyond national jurisdictions. Environmental concerns have further complicated progress, having prompted 32 countries and the European union to support a deep-sea mining moratorium.
This article examines the evolving legal framework behind deep-sea mining, with a focus on the International Seabed Authority’s (ISA) upcoming mining code regulating mineral resource exploitation outside of national jurisdictions, targeted for release in mid-2025.
The Current Regulatory Landscape
At present, deep-sea mining is regulated primarily by the United Nations Convention on the Law of the Sea (UNCLOS). Article 56 of UNCLOS grants countries the right to exploit resources within their own exclusive economic zones (EEZs), which extend up to 200 nautical miles from their coastlines. However, these activities must adhere to environmental obligations also outlined in UNCLOS, including article 192, which mandates the protection and preservation of the marine environment, and article 194, which obligates efforts being taken to prevent, reduce and control pollution of the marine environment.
Beyond national jurisdictions lies “The Area”, deemed the “common heritage of mankind” in article 136 of UNCLOS. The ISA is the body in charge of regulating activities within this zone for the 170 UNCLOS signatories. While the ISA has issued 31 exploratory licenses for deep-sea mining so far, no exploitation licenses have been issued.
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In 2021, the island nation of Nauru invoked the two-year rule, a clause in UNCLOS requiring the ISA to finalise a legally binding mining code for The Area within two years. However, the mining code was not completed within this timeframe. This raised concerns that Nauru Ocean Resources Inc. (NORI), a Nauru-sponsored subsidiary of The Metals Company, might apply for an exploitation license without finalised legislation.
In response, the ISA asserted that “commercial exploitation of mineral resources in The Area should not be carried out in the absence” of regulations. A new target of July 2025 was set for the release of the mining code.
The Mining Code: Striking the Right Balance
Proponents of deep-sea mining claim that it could reduce the environmental impact of terrestrial mining and shift the burden away from areas inhabited by humans. Land-based mining operations often lead to habitat destruction, pollution and significant carbon emissions. Deep-sea mining may reduce the need for some land-based mines, particularly those involved in the exploitation of metals found in polymetallic nodules such as manganese, cobalt, nickel and copper, leading to less environmental destruction on land attributable to mining. It may also be a more ethical alternative - unlike some terrestrial mining operations, which can rely on extensive human labour under unsafe conditions, deep-sea mining mainly utilises machinery.
Moreover, the metals extracted from polymetallic nodules are critical components of electric car batteries and other green technologies, positioning deep-sea mining as a potential catalyst for the global energy transition away from fossil fuels. With this point in mind, several countries advocating for the practice to begin - including Nauru, Kiribati and Tonga - who all sponsor subsidiaries of Canadian-based prospective deep-sea mining firm The Metals Company (TMC) – highlight their unique vulnerabilities to climate change.
These small island nations face disproportionate threats from rising sea levels compared to countries at higher elevations, despite having contributed minimally to historic global greenhouse gas emissions. Proponents of deep-sea mining argue that allowing these countries to benefit from mineral resource exploitation in The Area could provide them with a reparatory economic boom, some of which could be spent on climate change mitigation measures, while simultaneously accelerating the global shift away from the fossil fuels that threaten their very survival.
However, significant controversy also surrounds the environmental implications of deep-sea mining.
Critics warn that mining machinery may aerate and disturb sea floor sediments, dispersing plumes of suspended particles across large areas of the ocean, harming filter-feeding and photosynthesising species. These disruptions would likely cascade through the food chain, ultimately affecting humans. In addition, noises caused by mining machinery could interfere with some marine species, disturbing their communications and having other unpredictable effects on their behaviour and migratory patterns. Given the fragility of marine ecosystems, their slow recovery rates and the fraught potential for unintended consequences associated with marine processes we don’t yet understand, the environmental costs of mining in these areas would likely outweigh those associated with terrestrial operations.
That being said, proponents of the practice may argue that technological advancements in mining machinery and innovative environmental safeguards could over time minimise its environmental impact. In addition, some may view the critical metals within polymetallic nodules as so vital for the green transition that any environmental costs of deep-sea mining are a necessary burden for the planet to bear in order to secure its long-term health.
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A strong counter-argument to this point of view is that the impact of deep-sea mining may extend to increasing the level of the very climate change that it seeks to alleviate. Vast quantities of carbon trapped in deep-sea sediments would likely be released by the mining process, which could further exacerbate climate change and ocean acidification, according to a report by conservation group Fauna & Flora.
A recent study has further fuelled the debate by suggesting that polymetallic nodules may facilitate “dark oxygen” production via seawater electrolysis, which could play a significant role in the biogeochemical cycles of the deep oceans and hence be important for preserving deep-marine wildlife and consequently organisms at higher trophic levels. This discovery challenges the previous assumption that deep marine ecosystems rely on oxygen originally derived from photosynthesis in photic waters, demonstrating the exigency for more research into the potentially substantial ecological role played by these nodules.
In essence, the consequences of deep-sea mining remain poorly understood, and as such, there is fervent opposition to it from large numbers within the scientific community. To date, over 900 marine science and policy experts have signed an open letter calling for a pause in its development.
With all these competing perspectives in mind, the ISA’s mining code must address several critical considerations:
The trade-off between economic and environmental factors
While deep-sea mining could deliver large economic benefits to developing nations and sectors reliant on critical metals such as those required for the Green Transition, it also has the potential to cause irreversible harm to the marine environment and ecosystems. The mining code could provision for this by mandating environmental impact assessments (EIAs) and ongoing monitoring requirements for mining operations, or by introducing a moratorium system where mining activities are paused if pre-defined ecological thresholds are breached.
The “common heritage of mankind”
The principle of “common heritage of mankind” outlined in UNCLOS calls for the equitable sharing of benefits derived from The Area’s resources. This must be addressed by the ISA’s mining code in order to prevent the selfish exploitation or monopolisation of The Area’s resources by powerful nations and corporations. For example, it could introduce a royalty system where profits from deep-sea mining are redistributed globally, especially to nations most affected by climate change. A transparent fund managed by an independent body could be set up to avoid corruption and favouritism.
Provision of punishments for non-compliance
If countries and corporations breach the rules set out by the mining code, they must be penalised. Enforcement mechanisms would ensure that regulated parties adhere to these rules. These could include measures such as hefty fines, mining suspensions, license revocations and loss of voting rights in the ISA for a period of time which depends on the severity of the breach.
Facilitation of international dispute resolution
A specialised tribunal set up under the ISA could resolve disputes over compliance and impose penalties on those involved in malpractice. Affected parties, such as sponsoring states or environmental groups, could then file claims against non-compliant entities and submit formal complaints. Over time, the tribunal’s decisions would establish legal precedents for future cases, gradually creating a body of law specific to deep-sea mining. These precedents could then be used to clarify ambiguous sections of the mining code and refine enforcement mechanisms.
What’s next for deep-sea mining?
In August 2024, the former secretary general of the ISA, Michael Lodge, was voted out of his position owing to concerns over his appearance in a promotional video by The Metals Company and his alleged lack of impartiality. His replacement, Leticia Carvalho, has a more precautionary approach to deep-sea mining, emphasising the need for environmental protection. In an interview, she stated: “the ISA is to deliver deep-sea mining — it is there for it — but in doing so, it has to deliver it on the promise not to harm the environment”.
This stance is reflected in the ISA’s most recent draft exploitation regulations, which currently govern applications for mining exploitation licences in the absence of finalised regulations. The draft mandates that applicants submit a “plan of work” demonstrating “effective protection of the Marine Environment, including biological diversity and ecological integrity”. It also requires states to provide an Environmental Impact Statement (EIS) to the ISA as part of the process for obtaining an exploitation license, and outlines the financial obligations of contractors, including fees and contributions to the ISA’s Enterprise, which is designed to promote the participation of developing states in mining activities by providing them with access to technology, expertise and financial resources. These provisions in the draft exploitation regulations may offer reassurance to environmental advocates concerned about the potential for deep-sea mining to cause irreversible damage to the ocean’s fragile ecosystems.
The ISA aims to release the finalised mining code that will govern deep-sea resource exploitation in international waters in July 2025. While some observers have suggested this will not be possible in such a short timeframe - especially considering many unsolved issues were raised during the last meeting in July 2024 - when the finalised mining code is released, it will have lasting implications in the development of the emerging deep-sea mining industry.
The Metals Company, who have already invested hundreds of millions of dollars into deep-sea mining, will be waiting in great anticipation.
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