Deep-sea mining for rare earth elements and other critical minerals has rapidly moved from a speculative possibility to a tangible policy option at the forefront of contemporary debates on energy transitions, industrial strategy, and environmental stewardship. The deep ocean, long considered one of the last great global commons, is increasingly reframed as a potential source of metals indispensable to low-carbon technologies, digital infrastructure, and advanced defence systems. This shift raises a fundamental question: can the pursuit of supply security for critical minerals be reconciled with the precautionary protection of largely unexplored marine ecosystems?
Critical minerals such as cobalt, nickel, manganese, copper and REEs underpin batteries, permanent magnets, power electronics and a wide range of civilian and military applications. Forecasts for net-zero pathways anticipate substantial increases in demand for several of these materials by 2040 driven by electric vehicles, renewable power, grid storage and data-centre expansion. At present, extraction and processing are geographically concentrated: China dominates the rare earth value chain and holds major positions in refining several other critical minerals, while a small group of nation-states controls most established cobalt and nickel production. This has transformed critical minerals into instruments of statecraft, prompting consuming states to treat diversification of supply as an issue of national security rather than merely commercial choice.
Against this backdrop, deep-sea deposits appear as an alluring alternative. Three principal mineral systems attract interest: polymetallic nodules scattered over abyssal plains; cobalt-rich ferromanganese crusts on seamounts; and polymetallic sulphides at or near active and inactive hydrothermal vents. Nodules, in particular, contain significant quantities of manganese, nickel, copper and cobalt, while crusts are enriched in cobalt and may host elevated concentrations of certain REEs and other high-value trace metals. Scientific surveys and resource assessments suggest that the metal content of these deposits, especially in regions such as the Clarion-Clipperton Zone, could rival or exceed known terrestrial reserves for some commodities, at least in gross geological terms. Proponents argue that tapping these resources would reduce dependence on politically fragile land-based operations, alleviate bottlenecks in critical mineral supply, and potentially avoid some social harms associated with terrestrial mining like displacement of communities and direct worker exposure to hazardous conditions.
However, deep-sea mining is emerging not only as a technical or economic issue but also as a profound ecological and normative challenge. The ecosystems targeted for future operations are characterised by extreme conditions, slow biological processes, and high levels of endemism; many species associated with nodules, crusts and vent fields have only recently been described, and scientific knowledge of their functional roles remains limited. Experimental disturbances in nodule provinces indicate that physical removal of nodules and associated sediments can leave detectable ecological scars for decades, with incomplete or highly uneven recovery of benthic communities even after 40 years. Sediment plumes generated by collector vehicles and return-water discharges risk transporting fine particles and adsorbed metals far beyond mining sites, with uncertain but plausibly extensive impacts on filter-feeding organisms and pelagic food webs. In addition, the deep ocean contributes to long-term carbon storage and global biogeochemical cycles, raising concerns that large-scale industrial disruption could have system-level feedbacks that are currently poorly constrained.
Institutionally, governance of mineral activities beyond national jurisdiction is anchored in the International Seabed Authority, which administers the “Area” and its resources designated as the “common heritage of mankind” under the United Nations Convention on the Law of the Sea. The ISA has issued numerous exploration contracts to state-sponsored enterprises and private consortia but is yet to finalise a comprehensive exploitation code establishing binding environmental standards, monitoring requirements and benefit-sharing mechanisms. Negotiations over this “mining code” have exposed deep divisions between states and stakeholder coalitions: some coastal and industrialised countries favour an accelerated move to commercial production, while others, supported by scientific and civil-society networks, advocate a moratorium or precautionary pause until baseline data and robust safeguards are in place. Small Island Developing States in the Pacific, many of which sponsor contractors or lie adjacent to prospective mining zones, are themselves divided between development aspirations and fears of long-term damage to fisheries, cultural relationships with the ocean and climate resilience. A particularly salient theme in recent scholarly work is whether deep-sea mining is necessary to meet projected mineral demand, especially for rare earths. Studies of REE-rich muds and ocean-floor sediments indicate that the deep ocean does contain potentially significant REE resources, often associated with iron–manganese (hydro)oxides and apatite phases. Yet critical assessments underline that most current seabed mining interests focus on base metals in polymetallic nodules and cobalt-rich crusts, with rare earths typically appearing as by-products rather than primary targets. Moreover, global geological surveys suggest that terrestrial reserves of both REEs and the base metals now targeted remain substantial relative to plausible demand trajectories, even under rapid decarbonisation scenarios.
Scholars arguing against a rush to the seabed contend that expanding conventional mining in conjunction with process improvements, material substitution, more efficient product design and systematic recycling could accommodate growth in demand without opening a new extractive frontier. From a normative perspective, the deep-sea mining debate crystallises wider tensions within sustainable development. One vision prioritises rapid deployment of low-carbon technologies backed by diversified mineral supply chains and framed as a necessary trade-off to avoid the far greater risks of unmitigated climate change. Another emphasises planetary boundaries and the intrinsic value of poorly understood ecosystems, arguing that decarbonisation strategies should not replicate historical patterns of frontier exploitation and environmental sacrifice zones. A more critical strand asks distributional questions: who bears ecological risk, who captures rents from common heritage resources, and how governance structures can prevent the enclosure of deep-sea commons by a narrow set of corporate and state actors.
In this light, the question of deep-sea rare earths is less about absolute scarcity than about choices among competing pathways to sustainability. Energy transitions undoubtedly require metals; they do not, however, predetermine that societies must industrialise the ocean floor. Evidence to date suggests that a combination of prudent terrestrial resource management, circular-economy strategies and technological innovation could substantially reduce the ostensible imperative for rapid seabed exploitation, particularly in relation to REEs. Whether the international community chooses to pursue deep-sea mining will reveal much about prevailing priorities: security of supply vs ecological integrity, short-term flexibility vs long-term uncertainty, and narrow national interests vs the collective responsibilities implied by the notion of common heritage.
Upasna Mishra is a PhD Research Scholar and SYLFF Fellow, School of International Relations and Strategic Studies, Jadavpur University