Deep-Sea Mining and the ISA

Nodules, Crusts, and Sulphides: Three Deep-Sea Mineral Systems

Before examining the governance debate, it is worth clarifying what mineral systems are at stake. Deep-sea mining encompasses three distinct resource types. Polymetallic nodules—the focus of most CCZ interest—form on sediment surfaces in the abyssal Pacific and Indian Oceans. Polymetallic sulphides precipitate from hydrothermal vent fluids at mid-ocean ridges, forming chimney and mound structures rich in copper, zinc, gold, and silver in waters typically 1,500–3,500 m deep. Cobalt-rich ferromanganese crusts form on the flanks of seamounts and ridges at 800–2,500 m depths. Each system hosts distinct biological communities; each presents different engineering challenges; and each is governed by the same regulatory body—the International Seabed Authority (ISA)—under the framework of the United Nations Convention on the Law of the Sea (UNCLOS), which designates the deep seabed beyond national jurisdiction as the 'common heritage of mankind' [1].

The CCZ polymetallic nodule field dominates commercial attention for straightforward reasons of scale and concentration. The ISA's environmental management plan for the CCZ, published in 2014, described an area of approximately 6 million km² with an estimated 21 billion dry tonnes of nodules at economic grades—a figure that, at current projections for EV battery demand, would supply enough nickel and cobalt to manufacture billions of battery packs [2]. Nine designated Areas of Particular Environmental Interest (APEIs) within the CCZ management plan were established to function as biodiversity refugia, protecting representative habitats from mining impacts, though scientists have debated whether the initial APEI network adequately captures the full spatial range of CCZ biodiversity [2].

What Lives Down There: Amon et al. 2016 and the Abyssal Menagerie

The early framing of deep-sea mining—that the abyssal plain is an ecological desert, too cold and dark and barren to support meaningful biodiversity—was decisively challenged by decades of biological exploration. A landmark 2016 paper by Diva Amon and colleagues in Scientific Reports presented the first rigorous trawl-and-ROV survey of megafaunal communities in the eastern CCZ [3]. Using ROV image analysis and physical sampling across multiple sites within a licensed exploration contract area, the team documented extraordinary abundance and taxonomic richness: holothurians, polychaete worms, xenophyophores (the world's largest single-celled organisms), isopods, ophiuroids, sponges, and numerous taxa that proved entirely new to science upon morphological and genetic analysis.

Critically, Amon et al. found that nodule density was the strongest predictor of megafaunal abundance and diversity: the nodule surface itself is a biological substrate, colonised by organisms that have nowhere else to live [3]. Xenophyophores—giant protists up to 20 cm across—anchor to nodule surfaces; sponges and stalked crinoids attach to nodule edges; diverse invertebrate communities shelter in the nodule interstitial spaces. Remove the nodules and you remove not only the mineral resource but the physical architecture of the ecosystem. On geological timescales of nodule formation, ecological recovery is essentially impossible—experimental disturbance tracks from the 1970s–1980s DISCOL and IOM BIE experiments in the CCZ show that megafaunal communities remain severely depleted and community-composition altered more than 25 years after even limited physical disturbance.

Van Dover and the Biodiversity Loss Calculus

The scientific case against deep-sea mining—or at minimum, for extreme caution—was synthesised most influentially by Cindy Lee Van Dover (Duke University) and 14 co-authors in a 2017 Nature Geoscience perspective, 'Biodiversity loss from deep-sea mining' [4]. The paper's argument was measured but unambiguous: regardless of which specific area is mined, biodiversity loss will occur and will be irreversible on any timescale relevant to human civilisation. The reasoning rests on three pillars. First, the low connectivity of abyssal populations means local extinction may be permanent rather than temporary—larvae cannot simply recolonise from adjacent patches at thousands of kilometres distance. Second, the sediment plumes generated by nodule collection equipment spread at neutrally buoyant depths for hundreds of kilometres, smothering filter-feeding organisms across areas far larger than the immediate mining footprint. Third, the extreme sensitivity of abyssal organisms to physical disturbance, water-chemistry changes, and light makes mitigation through operational adjustments insufficient to prevent significant biodiversity impact.

Van Dover's earlier work on hydrothermal vent systems added a parallel dimension to the concern [5]. Polymetallic sulphide deposits at active vents support ecosystems of extraordinary endemism—tube worms, vent shrimp, chemosynthetic bacteria—found nowhere else on Earth. The 2018 Marine Policy paper by Van Dover and colleagues provided the scientific rationale and international legal framework for protecting active vent systems outright, arguing that the unique nature of vent biodiversity creates an obligation under UNCLOS's 'common heritage of mankind' principle to prevent mining until vent ecosystems are adequately characterised and protected [5].

The ISA: Structure, Mandate, and the Mining Code

The International Seabed Authority, established in 1994 under UNCLOS and headquartered in Kingston, Jamaica, is simultaneously the regulatory body overseeing deep-sea mining and the entity responsible for ensuring environmental protection of the Area—a dual mandate that critics argue creates a structural conflict of interest. The ISA operates through three principal organs: the Assembly (all 172 member states), the Council (36 elected members), and the Secretariat. Decisions on exploitation regulations are taken in the Council, where commercial-interest actors can delay or weaken environmental standards [6].

As of 2024, the ISA has issued 31 contracts for exploration in the Area, covering polymetallic nodules, sulphides, and cobalt-rich crusts, with contractors including state-sponsored entities from China, Russia, South Korea, France, Germany, India, and private companies from Canada, Belgium, and Nauru. The Mining Code—the exploitation regulations that would authorise commercial nodule extraction—remains under negotiation. No exploitation contracts have yet been approved; the ISA remains at the exploration phase for all contractors [1].

The Two-Year Rule and the 2024 Moratorium Debate

The regulatory timeline was dramatically accelerated in 2021 when the Pacific island nation of Nauru, acting on behalf of its sponsored contractor (The Metals Company's Nauru Ocean Resources Inc.), formally invoked the two-year rule under UNCLOS Annex III, Article 5(1). This provision obliges the ISA Council to complete exploitation regulations within two years of such notification, or else be compelled to consider applications under existing (incomplete) regulations. The deadline fell in July 2023 and was not met—exploitation regulations remain unfinished—but the trigger created enormous political pressure and crystallised the governance debate.

In response, a growing bloc of states has called for a precautionary pause or moratorium on ISA exploitation approvals until environmental standards are established, independent oversight mechanisms are created, and scientific baselines are adequate. A detailed legal analysis published in 2024 in Ocean Development and International Law concluded that a pause is legally feasible under UNCLOS and consistent with the precautionary approach mandated in the ISA's own environmental regulations [7]. The same year, a review of ISA governance dynamics in npj Ocean Sustainability documented structural tensions between resource-extracting states and conservation-oriented states, noting that procedural blocking by commercial-interest actors had repeatedly delayed the adoption of stronger environmental clauses in draft exploitation regulations [6].

By the first half of the ISA's 29th annual session in March 2024, the moratorium coalition had expanded to include Chile, Costa Rica, Fiji, France, Germany, New Zealand, Panama, Palau, and the Federated States of Micronesia, among others [8]. France's position was particularly significant: as the sponsoring state of the French Research Institute for Exploitation of the Sea (Ifremer) exploration contractor, France's pivot to supporting a pause marked one of the starkest examples of a commercial-interest state reconsidering its position on environmental grounds.

The Strategic Minerals Dilemma: Batteries vs. Biodiversity

Proponents of deep-sea mining frequently invoke the clean-energy transition as a moral trump card: the cobalt, nickel, and manganese in CCZ nodules are essential for lithium-ion batteries; terrestrial mining of these metals in the DRC, Philippines, and Indonesia is associated with documented human rights abuses, child labour, and severe ecosystem destruction; therefore, mining an apparently unpopulated abyssal plain is the lesser evil. The argument deserves serious engagement—it is not transparently cynical—but it contains several empirically contestable claims.

First, 'apparently unpopulated' is no longer a defensible characterisation of CCZ abyssal communities in light of the evidence accumulated since Amon et al. (2016) [3]. Second, the comparison with terrestrial mining ignores the spatial scale asymmetry: a single CCZ mining lease block covers approximately 75,000 km²—larger than many nation-states—and the ecological footprint of sediment plumes extends far beyond the immediate collection track. Third, battery chemistry is evolving rapidly toward lithium-iron-phosphate (LFP) and sodium-ion formulations that reduce or eliminate cobalt dependence; the demand projections underpinning CCZ economic viability were built on battery technology assumptions that may not hold a decade from now.

None of this resolves the dilemma. Terrestrial alternatives have their own ecological and social costs. The question is not whether mining has costs, but whether the governance framework for deep-sea mining is adequate to manage those costs transparently, equitably, and with genuine protection for a commons that belongs, under international law, to all humanity and to future generations. Scientists like Van Dover, Amon, and their collaborators have provided the empirical foundation for that assessment [3,4,5]. What the ISA, its member states, and the watching world do with that foundation remains, as of 2024, an open and urgent question.

What Responsible Governance Would Look Like

There is growing academic and legal consensus on what a credible governance framework for deep-sea mining would require. Independent environmental impact assessment, conducted by scientists with no contractual relationship to the applicant. Real-time monitoring and telemetry from mining equipment with immediate shut-down authority vested in ISA inspectors. Regional environmental management plans updated as new scientific data arrive, with APEI boundaries subject to revision based on connectivity and biogeographic evidence. A benefit-sharing mechanism that ensures developing nations—particularly the Pacific island states whose exclusive economic zones adjoin the CCZ—receive meaningful economic returns and genuine decision-making power, not merely consultation rights. And a precautionary moratorium mechanism that can be invoked by a qualified majority of the Assembly when scientific evidence of unacceptable risk reaches a defined threshold [7].

None of these features is currently embedded in ISA regulations. The Mining Code negotiations, still ongoing, will determine whether they ever are. For those who believe the deep sea—the largest habitable environment on Earth, the least understood, and the most vulnerable to permanent alteration—deserves governance commensurate with its ecological importance, the next several ISA sessions may be among the most consequential environmental governance events of the decade.