Frequently Asked Questions

While there may be technically enough metal-bearing deposits on land to meet future demand (1), those resources can only be extracted at increasingly high economic, social, and environmental cost. We believe that polymetallic nodules could contribute to supplying metal resources and alleviate some of the pressures on fragile terrestrial ecosystems.

Access to—and development of—land-based deposits is getting harder. Falling grades mean that to get the high quality of metals needed for renewable technology, companies are forced to dig deeper and wider, creating more harm and spending more capital. Nickel, cobalt, and manganese deposits are naturally located in some of the planet’s most biodiverse places, including Indonesia, the Democratic Republic of Congo (DRC), and South Africa. Additionally, many terrestrial mining supply chains experience issues with labor rights and violations, such as child labor in cobalt mining in the DRC(2)(3). Of all mined commodities, nickel is the most vulnerable (4).

Since 2021, almost 100% of the growth in the supply of nickel has come from nickel laterites beneath the rainforests of Indonesia, and this growth is expected to continue. The rapid growth in the production of rainforest nickel has resulted in widespread deforestation in these unique ecosystems, and contamination of local community water supplies by harmful carcinogens resulting from waste generated during nickel laterite processing.

Producing these metals from polymetallic nodules could reduce most of the Environmental, Social, and Corporate Governance (ESG) costs of conventional metal production. One nodule contains high grades of four key metals, meaning that four times less ore needs to be processed to obtain the same amount of metal. And with few impurities, the entirety of a nodule’s mass can be used. We have already demonstrated that we can process nodules into metal products with near-zero solid waste and zero tailings. Because nodules sit unattached on top of the seafloor, they will not require drilling or blasting for retrieval.

We recognize that it is unlikely that deep-sea mining will completely replace terrestrial mining. But in the face of increasing demand for metals, we feel it is important to supplement metals supplies in a way that inflicts the least impact on the planet and people. This means giving fragile rainforest ecosystems a break, and increasing the supply of high-quality metals which can be recycled and reused to slowly build up a stock of metal that lessens the need for virgin ores gradually over time.

<sub>1. Demand side: International Energy Agency (IEA) (2025). Global Critical Minerals Outlook 2025. [Online Report] IEA.; Supply side: U.S. Geological Survey (USGS) (n.d.). USGS Mineral Commodity Summaries [Online Reports]. Drawn from USGS supply-side data for nickel, cobalt, copper and manganese
2. Faber, B., Krause, B., & Sánchez de la Sierra, R. (2017). Artisanal Mining, Livelihoods, and Child Labor in the Cobalt Supply Chain of the Democratic Republic of Congo. UC Berkeley: Center for Effective Global Action. Retrieved from escholarship.org/uc/item/17m9g4wm.
3. Kelly, A. (2019, December). Apple and Google named in US lawsuit over Congolese child cobalt mining deaths. The Guardian.
4. Verisk Maplecroft (2021, October). Mining operations face growing biodiversity risks. Retrieved from https://www.maplecroft.com/insights/analysis/2021/mining-operations-face-growing-biodiversity-risks/.</sub>

The drive to decarbonise and transition away from fossil fuels is increasing demand for mined metal. We should both reduce our consumption and recycle metal, but over the next 30 years, the impact of these measures on demand for mined metal will be marginal. The amount of spent electric vehicle (EV) batteries that are expected to reach the end of their first life is forecast to surge after 2030, but with mineral demand growing rapidly, the International Energy Agency predicts that recycled quantities of copper, lithium, nickel and cobalt from spent batteries would only reduce primary supply requirements by around 10% ⁽¹⁾. In other words, we can’t recycle what we don’t have. As long as the transition’s projected needs exceed existing stocks, we’ll need to increase the amount of existing metals before closing the loop. 

The global light passenger vehicle fleet — currently ~ 1.2 billion cars — is projected to increase to 2 billion by mid-century⁽²⁾. Demand-side reductions, such as carpooling or shared ownership, and incentivizing public transit can help reduce this projection but likely won’t negate the need to electrify the existing internal combustion engine (ICE) fleet. A conventional ICE car, on average, contains five times less selected metal mass than that required to build an EV. Even if we recycled every existing gas and diesel car, and dramatically increased ride sharing and robotic car access, we would still need a significant new injection of virgin metals to transition from ICE cars to EVs. 

We believe product redesign and circular-economy solutions should be pursued now and phased in so that they can be leveraged as growth tapers off. To achieve this, we plan to contribute to a circular battery metals supply chain to dramatically reduce—and eventually eliminate—the need to take any more metals from the planet. While this will take several decades, we expect it could be possible by the latter half of the 21st century.

<sub>1. Demand side: World Bank. (2020, April). The Mineral Intensity of the Clean Energy Transition; supply side: U.S. Geological Survey. USGS.gov | Science for a changing world. (n.d.). usgs.gov.
2. Future of Auto Market Runs on Batteries. Morgan Stanley. (2017). morganstanley.com/ideas/electric-cars-sales-growth.</sub>

The biggest threat to the oceans is climate change. We believe the top priority for the entire planet—including the oceans—should be achieving net-zero emissions.

Staying dependent on fossil fuels will continue to contribute to a host of environmental and climate issues—ocean acidification, oil spills, toxic byproducts, and resource wars among them. Shifting away from carbon-based energy requires a huge amount of energy generation and storage capacity. Whether for solar panels, wind turbines, or geothermal or nuclear power generation, the bulk of these technologies will be made of yet-to-be-sourced metals that need to be sourced with the lowest impact possible.

High-grade and easy-to-access metals have already been extracted on land. What remain are of low grade, and their extraction comes with ever-increasing economic and environmental costs: miners must dig harder and deeper for every tonne of rock they remove, discarding as much as 99% of this mined material as waste or toxic tailings in the process. These mined ores are increasingly sourced from highly biodiverse and unique ecosystems, particularly in the case of nickel which is largely found beneath equatorial rainforests. These forests sequester carbon for the entire planet, land and oceans combined.

Peer-reviewed lifecycle impact assessments show that the nodule resource provides a rare opportunity to reduce the associated climate impacts by up to 90% compared to equivalent ores on land (1). Multiple lifecycle assessments by independent organizations show that metal products from TMC’s first nodule project would result in fewer greenhouse gas emissions than almost every key production route for nickel, cobalt, copper and manganese (2).

<sub>1. Paulikas, D., Katona, S., Ilves, E. and Ali, S.H. (2020). Life cycle climate change impacts of producing battery metals from land ores versus deep-sea polymetallic nodules. Journal of Cleaner Production, 275, p.123822. doi:https://doi.org/10.1016/j.jclepro.2020.123822.
2. Since 2019, TMC has commissioned and published several industry-specific LCAs. As TMC’s project has progressed, it has also commissioned and published multiple lifecycle assessments using the latest data on how we expect to collect and process our nodules. Learn more here at metals.co/lifecycle</sub>

There are three distinct types of deep-sea resources, each of which are found in differing ecosystems and vary in their impacts.

1. Cobalt crusts precipitate on the flanks of submarine volcanoes (or “seamounts”) as metallic layers that form an integral part of the seafloor and require cutting hard rock to separate the ore from the substrate. At depths of between 800–2,500 meters, the local ecosystem enjoys an abundant food supply, thanks to the upwelling of nutrient-rich water, which enables a proliferation of life—including large predators such as tuna and sharks—between 10 to 100 times greater than is found on the abyssal plain.
2. Seafloor massive sulfides are tall, chimney-like structures that form around hydrothermal vents spewing forth metal-enriched waters from the seafloor. Similar to cobalt crusts, these formations are an integral part of the seafloor and require hard-rock cutting to separate the ore from the substrate. At depths of between 1,000–4,000 meters, bacteria, which exploit chemical compounds from the vents, supply this ecosystem with an abundance of food, supporting biomass levels 100 times greater than those on the abyssal plain.
3. By contrast, polymetallic nodules lie unattached atop the abyssal seafloor and can be collected using water jets directed at the nodules in parallel with the seafloor—without any digging or drilling. At depths of between 4,000–6,000 meters, the abyssal seafloor in the Clarion Clipperton Zone is a stable environment characterized by near-freezing temperatures, extreme pressures and little food, making it one of the least productive areas of the ocean with one of the lowest biomass levels of any planetary ecosystem.

The ocean is the planet’s largest carbon sink, but most of this carbon is stored in the water column, not in seafloor sediments.

As organic carbon sinks from more productive surface waters, it is consumed and recycled by marine organisms, fixing the majority of this carbon in the water column. Less than 5% of total marine carbon is ultimately stored in sediments, with only a small fraction reaching abyssal depths of 4–6km where nodules are found (1).

This lack of food means the abyssal plains host very little life, which is dominated by microbes. The potential impacts of nodule collection operations on the ability of these microbes to sequester carbon in abyssal sediments were addressed directly in 2020 and found to be “trivial” (2).

While collector vehicles operating on the abyssal seafloor will mobilize the top few centimeters of sediment, between 95–98% of this sediment is separated from nodules and redeposited directly at the seafloor, where it settles within 1–2 km and rises only a few meters (3). As a result, no known pathway exists for disturbed sediment to rise naturally over 4km through the water column to the surface. The only potential pathway for sediment to reach the surface is through the riser system. However, data from the 2022 test mining campaign show that the 2–5% of sediment that escapes separation at the seafloor and rises along with nodules and seawater to the surface results in negligible carbon emissions.

Contrary to the claim that nodule collection could make climate change worse, peer-reviewed research comparing the lifecycle climate change impacts of sourcing nickel, cobalt, copper and manganese for 1 billion electric vehicles from the nodule resource versus land-based ores shows that nodules would reduce the associated climate change impacts by 90% (4).

<sub>1. Friedlingstein, P. (2023). Global Carbon Budget 2023. Earth System Science Data, 15(12), pp.5301–5369. doi:https://doi.org/10.5194/essd-15-5301-2023.
2. Orcutt, B.N., Bradley, J.A., Brazelton, W.J., Estes, E.R., Goordial, J.M., Huber, J.A., Jones, R.M., Mahmoudi, N., Marlow, J.J., Murdock, S. and Pachiadaki, M. (2020), Impacts of deep-sea mining on microbial ecosystem services. Limnol Oceanogr, 65: 1489-1510. https://doi.org/10.1002/lno.11403
3. Webber, A., Bento, J., Marsh, L., Downes, P., O’Malley, B., Ingels, J. and Clarke, M. (2025). Benthic plume generation from a production-scale model of polymetallic nodule collection. Data presented at Underwater Minerals Conference 2025.
4. Paulikas, D., Katona, S., Ilves, E. and Ali, S.H. (2020). Life cycle climate change impacts of producing battery metals from land ores versus deep-sea polymetallic nodules. Journal of Cleaner Production, 275, p.123822. doi:https://doi.org/10.1016/j.jclepro.2020.123822.</sub>

While understanding and witnessing the environmental and social damages of land-based metal production is one thing, reducing them is another (1). The theoretical potential for reducing harm on land is severely constrained: We can’t change the fact that the grades of remaining ores are low and falling, nor can we change the fact that if the rock contains only 0.5% of target metal, the other 99.5% will become a waste stream. We also can’t change the fact that remaining metal deposits are located in places with high biodiversity, often on Indigenous land.

The lifecycle Environmental, Social, and Corporate Governance (ESG) footprint for land-based production can be improved, but in most cases, it will be worse than that of nodule-derived metals. This is because the starting point for the nodule resource is fundamentally different: rich concentrations of four metals in a single rock; an entirely usable rock mass; a common and extreme environment with limited life; and no threat to Indigenous land.

Additionally, the Clarion Clipperton Zone is physically remote, but will not be “out of sight, out of mind.” Adaptive Management Systems (AMS) have been recognized as a key enabler of effective environmental management for deep-sea nodule collection, and provide a structured, iterative process of robust decision-making in the face of uncertainty, with an aim to reduce this uncertainty over time via active system monitoring. The Metals Company’s adaptive management system, a mix of deep-sea ecological data, marine sensors, and cloud-based A.I., will create a digital twin of our operating environment. This system will enable us to monitor what’s happening in near real time and give eyes and ears into our offshore operations to the regulator and stakeholders. This information, combined with expert analysis, will enable us to adapt, pause, and change our operations to stay within expected ecological thresholds and inform all stakeholders of our impacts at any point, from anywhere in the world.

_{1. Paulikas et al. (2020). Life cycle climate change impacts of producing battery metals from land ores versus deep-sea polymetallic nodules. Journal of Cleaner Production, 275. (doi.org/10.1016/j.jclepro.2020.123822.)}

Metal extraction—whether on land or from the deep sea—will impact ecosystems, but the extent and types of impacts are worth considering, and each source will come with a unique set of trade-offs.

Billions of tons of metal will be extracted from the planet over the next 30 years to meet energy-transition- driven demand alone. The abyssal seafloor carries 300 to 1,500 times less life (1) and stores 15 times less carbon than ecosystems on land (2). If we source critical metals from seafloor nodules, we could slow down the destruction of more biodiverse ecosystems, such as rainforests, which play a vital role in the earth’s climate cycle. Covering roughly 70% of global seafloor, the abyssal plain is the most common habitat on the planet. Even at scale, the nodule collection industry will likely impact only 0.4% (3) of the available abyssal habitat, a far smaller proportion than results from mining in rarer, more biodiverse rainforests which represent a very small percentage of available habitat on Earth. As a precautionary measure, more area within the Clarion Clipperton Zone has already been set aside for conservation than is currently under exploration (4).

<sub>1. Terrestrial biomass estimates from Houghton, R. A., and S. J. Goetz (2008), New satellites help quantify carbon sources and sinks, Eos Trans. AGU, 89(43), 417–418, doi:10.1029/2008EO430001; oceanic biomass estimates generated by GPT-4 with prompts to review peer-reviewed literature including on Bar-On YM, Phillips R, Milo R. The biomass distribution on Earth. Proc Natl Acad Sci U S A. 2018 Jun 19;115(25):6506-6511. doi: 10.1073/pnas.1711842115.
2. Paulikas et al. (2020, April). Where Should Metals for the Green Transition Come From? Deep Green. Retrieved from deep.green/white-paper.
3. Estimate assumes a highly improbable scenario where 50% of the 1.68 million km² of nodule exploration areas globally (international waters + EEZs) are exploited over a 30-year period, starting on the same day.
4. Report of the Chair of the Legal and Technical Commission on the work of the Commission at its twenty-sixth session: Decision of the Council of the International Seabed Authority relating to the review of the environmental management plan for the Clarion-Clipperton Zone, 10 December 2021, ISBA/26/C/58</sub>

Given the aggressive scale-up of demand for metals, shortages are likely to persist for some time as metal producers make the large investments required to scale up supply. As metal supplies grow over time, metal producers will start competing on price and sustainability.

At this point we expect that recycled metal will start displacing new metal supply from land-based sources due to its much better sustainability profile—even if it comes with a higher price tag. This scenario is supported by the fact that many jurisdictions around the world are making recycling of electric vehicle batteries a regulatory requirement. If done right, recycled metal is the only truly sustainable source of metal.

Metals derived from nodules will likely coexist with recycled metal for a few decades due to their lower production cost and lower ESG footprint, but will gradually be phased out as the world builds up sufficient stocks to enable a fully recycled metals commons.

We recognize that the introduction of commercial deep-sea mining would not completely replace land mining, even though the environmental benefits of doing so in the long run are clear (see “Why do we need deep-sea mining?”). What polymetallic nodules promise in the near term is an opportunity to supplement depleting terrestrial reserves to meet surging demand, and to give fragile land-based ecosystems a break and a chance to recover from the damaging and intensive mining currently occurring in places such as Indonesia and Congo. In the longer term, as the nodule industry scales – and as its financial and ESG advantages over land mining become clear – competitive pressure will be placed on terrestrial mining, with those projects at the higher end of the cost curve likely becoming too uneconomical to continue.

A good analogy is with power production. If a nuclear power plant or a wind farm is opened that may not mean that, say, a coal plant will be shut down. But that is not an argument against introducing more sustainable modes of power production. Over time, introducing more sustainable and cost-effective methods of power production has been shown to reduce countries’ dependence on fossil fuels such as coal, and while this has not been an automatic substitution, it has been a clear step in the right direction. The same principle is true with sourcing critical metals: it is better to introduce more sustainable mining practices now to meet soaring demand and put pressure on costly terrestrial mining projects, than delay the green transition and cause even worse damage to the climate.

While recycling practices for bulk metals are already well established, this is not yet the case for many energy-transition metals. Emerging waste streams from clean energy technologies (e.g., batteries and wind turbines) can change this picture. The amount of spent electric vehicle (EV) batteries reaching the end of their first life is expected to surge after 2030, at a time when mineral demand is set to still be growing rapidly. That’s why we’re studying how to best work with partners to recycle and redeploy the EV battery materials that we plan to source from polymetallic nodules.

While current metal recycling practices fall short and cannot immediately eliminate the need for continued investment in new supplies, it is possible that by 2040 recycled quantities of copper, lithium, nickel, and cobalt from spent batteries could reduce combined primary supply requirements for these minerals by around 10%, according to the International Energy Agency. By developing a closed-loop system of rental and redeployment partnerships around these critical metals as the EV market grows, we can ensure that the proportion of recycled battery metals continues to grow alongside it. Learn more here.

 

No ecosystem is immune to the impacts of industrial society, including the deepest parts of the (1) ocean. In its upper layers (0–2,000 meters), the ocean continues to warm unabated. It’s likely that this surface warming impacts the deep sea. The ocean is also continuing to acidify as it (2) absorbs more carbon from the atmosphere. With this in mind, the immediate priority should be reducing atmospheric carbon emissions to ease pressure on our oceans.

The question is not whether metals are needed. Meeting demand for clean energy, infrastructure, and growing populations will require a rapid and substantial increase in metal supply. Given that primary resource extraction – whether on land or at sea – will result in some level of impact, the question should be: how can we meet this booming demand while reducing the impact footprint as far as possible.

Today, the mining industry accounts for roughly 11% of global emissions and is the single largest producer of solid waste on our planet—producing over 100 times more waste than all our cities combined [3]. Conventional sources of supply on land will only deepen the degradation of our planet’s oceans and biodiverse ecosystems, increasing atmospheric carbon emissions and generating exponential growth in waste and tailings that must be stored on land or, at times, disposed of in the ocean.

An alternative approach is to prioritise resource extraction from environments that are far more abundant and support comparatively lower levels of biodiversity. The abyssal seafloor is one such environment: it is one of the largest habitats on Earth and hosts an order of magnitude fewer known species than many land- based systems. For example, the Clarion-Clipperton Zone is estimated to contain thousands of species, compared to the hundreds of thousands found in tropical rainforest regions such as Indonesia. Even at scale, the nodule collection industry would likely impact only 0.4% of the global abyssal plain. In this context, polymetallic nodules are considered by some to be a potential source of critical metals that could reduce pressure on more biodiverse and spatially limited terrestrial ecosystems.

<sub>1. Bindoff, N.L. et al. (2019). Changing Ocean, Marine Ecosystems, and Dependent Communities. IPCC Special Report on the Ocean and Cryosphere in a Changing Climate. Retrieved from ipcc.ch/srocc/chapter/chapter-5.
2. Ibid.
3. Market Glass, Inc. (2026). Mining Waste Management Market Size & Forecast to 2030. [online] Researchandmarkets.com. Retrieved from: https://www.researchandmarkets.com/report/mining- waste-management? utm_source=BW&utm_medium=PressRelease&utm_code=mgbcqw&utm_campaign=1432221+Glob al+Mining+Waste+Management+Market+Estimated+at+189.8+Billion+Tons+in+2020+Amid+COVI D-19+-+Industry+Analysis+and+Forecast+to+2027&utm_exec=joca220prd [Accessed 30 Mar. 2026].</sub>

To be clear, no deep-sea mining takes place today. The only activity currently underway is deep-sea research focused on baselining marine environments and characterizing the impacts of proposed operations. A moratorium on research will only lead to less research, and possibly a less informed approach to sourcing this critical resource.

Contractors such as The Metals Company are commissioning the majority of current deep-sea research. Many independently produced papers and reports have already been authored by researchers using TMC datasets, with dozens published in peer-reviewed journals. As researchers continue unlocking insights from our deep-sea dataset, we expect hundreds more to be published in the coming years. All researchers who participated in this program contractually maintain their academic freedom. More on this can be found on our Research page.

All mining has impacts, but where and how we mine matters. Land-based mining has already driven significant biodiversity loss, often in some of the most fragile ecosystems on Earth. Even in countries with strict environmental regulations, biodiversity-related impact studies usually focus on visible, above-ground species, overlooking the estimated 99% of microbial and 80% of worm species that live underground (1). As mining expands into tropical rainforests and other biodiversity hotspots, extinction risks are expected to rise—nickel production in Indonesia, the world’s largest producer, is of particular concern, and the metal has been described as the commodity most susceptible to biodiversity risks.

By contrast, nodule collection would take place at depths of 4–6 kilometers on the abyssal plains—the most abundant and one of the least biodiverse habitats on the planet. The abyssal plains cover about 60% of the Earth’s surface (2) and contain relatively low levels of biodiversity compared to terrestrial ecosystems. The Clarion Clipperton Zone (CCZ)—the region of greatest interest for nodule collection—is estimated to host 6,000–8,000 species, far fewer than terrestrial ecosystems, which range from hundreds of thousands to several million when all taxa (including microbes) are considered (3). As a food-limited ecosystem, the abyssal plain in the CCZ is dominated by microbes and small invertebrates spread across vast areas. Because life is so sparsely distributed and mining would affect less than 0.4% of the global abyssal plain (4) even in the most ambitious industry- growth scenario, the likelihood of driving species to extinction is very low.

Our operations will not strip mine the seafloor. They will create a mosaic of mined and untouched zones, with large reserve areas left intact as genetic reservoirs to support recolonization. Studies show that most invertebrates live in the top few centimeters of the sediment—not on the nodules themselves—and that recolonization begins quickly. Pioneer species such as foraminifera are among the first to return, rebuilding the sedimentary habitat that supports other life, while xenophyophores—giant, single-celled organisms—return to provide hard-substrate habitat for species reliant on the nodules themselves (5).

With careful design, ongoing research, and adaptive management, we believe the risk of species extinction from nodule collection is extremely low—especially compared with the biodiversity loss caused as terrestrial mining expands into less abundant and more biodiverse ecosystems on land.

<sub>1. Guardian News and Media. (2020, December 4). Global soils underpin life but future looks “bleak,” warns UN report. The Guardian. theguardian.com/environment/2020/dec/04/global-soils-underpin-life-but-future-looks-bleak-warns-un-report.
2. Paulikas et al. (2020, April). Where Should Metals for the Green Transition Come From? Deep Green. Retrieved from https://deep.green/white-paper.
3. Estimates for how described and total species break down by biome generated using Open AI’s GPT-4 based on review of sources that included peer-reviewed literature, WWF’s Global Ecoregions, IUCN Red List, scientific literature, GBIF, field guides, and conservation organizations.
4. Estimate assumes a highly improbable scenario where 50% of the 1.68 million km² of nodule exploration areas globally (international waters + EEZs) are exploited over a 30-year period, starting on the same day.
5. Simon-Lledó, E., Bett, B.J., Huvenne, V.A.I., Schoening, T., Benoist, N.M.A. and Jones, D.O.B. (2019), Ecology of a polymetallic nodule occurrence gradient: Implications for deep-sea mining. Limnol Oceanogr, 64: 1883-1894. https://doi.org/10.1002/lno.11157</sub>

Collecting deep-sea polymetallic nodules does not involve strip mining. Strip mining is the removal of vegetation, soil, and rock (also known as “overburden”) above a layer or seam of minerals, followed by the removal of the exposed mineral. During this process, the entire surface ecosystem is removed before excavation is used for softer rocks, and drilling and blasting is used to break up and remove the subsurface hard rock.

By contrast, polymetallic nodules are loose rocks sitting exposed on top of the seafloor, with 95% of nodule mass contained in the top 3-5 centimeters of sediment. There is no overburden to remove. Our modern collector vehicle uses advanced Coandă nozzles that direct jets of seawater across the nodules to gently lift them inside the machine. While 3-5 centimeters of soft mud under the nodules will travel inside the vehicle, test mining data show that our collector separates and redeposits 95–98% of this entrained sediment back at the seafloor (1). By perfectly spacing and individually articulating the nozzles to maintain an optimal height above the seafloor, the process minimizes sediment intake and seafloor impacts, and involves no strip mining, drilling or blasting of the seafloor (2).

Though concerns have been raised as to the potential scale of this industry, nodule collection is expected to impact a relatively small area of seafloor. In the unlikely scenario that half of all exploration areas in the Clarion Clipperton Zone moved into production, nodule collection would impact 40,000 square kilometers of abyssal seafloor per year for 30 years (3). This is less than 1% of the estimated 4,900,000 square kilometers of seafloor impacted every year by trawling, largely in much shallower and more (4) productive waters.

<sub>1. TMC Environmental Impact Assessment.
2. E. Baker, Y. Beaudoin (Eds.), Deep Sea Minerals: manganese Nodules, a physical, biological, environmental, and technical review, Secretariat of the Paci c Community, 1B (2013)
3. Estimate assumes a highly improbable scenario where 50% of the 1.68 million km² of nodule exploration areas globally (international waters + EEZs) are exploited over a 30-year period, starting on the same day.
4. Sala, E., Mayorga, J., Bradley, D. et al. (2021). Protecting the global ocean for biodiversity, food and climate. Nature 592, 397–402. doi.org/10.1038/s41586-021-03371-z.</sub>

Nodule collection operations generate two distinct plumes: a seafloor plume, which accounts for over 95% of total entrained sediment, is produced as collector vehicles disturb and resuspend sediments. A mid-water plume, formed mostly of seawater along with the small remaining fraction of entrained sediment not separated at the seafloor, is discharged from the riser outlet, carrying fine sediments into the mid-water column. For more on midwater plumes, see the following section.

Laboratory experiments, in-field monitoring of test mining, and simulated disturbances conducted by U.S. agency NOAA (1) first demonstrated that disturbed abyssal sediments generate a turbidity current that behaves as a dense, gravity-driven sediment flow, propagating along the seafloor under its own weight. In- field test mining campaigns later confirmed this behavior.

Based on their monitoring of a 2021 contractor mining trial, researchers at MIT determined that 92–98% of the resuspended sediment remained within two meters of the seafloor (2), and that the majority of this sediment dispersed in a turbidity current whose width was set quickly and remained stable even as it dispersed outwards (3). Data from TMC’s own mining tests corroborate these results, indicating that more than 91% of mobilized sediment settled within 1–2km of the collector tracks (4)(5).

Commercial-scale modeling conducted by DHI using TMC’s test mining and post-test-mining recovery data indicates that the vast majority of sediment settles within the direct collector tracks (6). After 18 months of continuous operation for our first project, sediment blanketing thick enough to cause lasting ecological effects would be confined to within 1km of the collector tracks. While there was concern that the plume could expand indefinitely, the model indicates that the plume reaches its maximum extent within a few days of the start of commercial operations and dissipates just as rapidly once operations cease.

Together, this evidence demonstrates that seafloor sediments settle quickly and remain near the bottom, with no pathway for carbon-poor sediment particles to rise from depths of 4km—eliminating the risk that nodule collection could contribute to greenhouse gas emissions.

<sub>1. Trueblood, Dwight D., and Erdogan Ozturgut. “The Benthic Impact Experiment: A Study of the Ecological Impacts of Deep Seabed Mining On Abyssal Benthic Communities.” Paper presented at the The Seventh International Offshore and Polar Engineering Conference, Honolulu, Hawaii, USA, May 1997.
2. Carlos Muñoz-Royo et al. (2022) An in situ study of abyssal turbidity-current sediment plumes generated by a deep seabed polymetallic nodule mining preprototype collector vehicle.Sci. Adv.8,eabn1219.
3. Raphael Ouillon, Carlos Muñoz-Royo, Souha El Mousadik, Thomas Peacock, A near field study of sediment plumes for a pre-prototype nodule collector trial in the abyssal Pacific Ocean, Deep Sea Research Part I: Oceanographic Research Papers, Volume 225, 2025, 104595, ISSN 0967-0637, https://doi.org/10.1016/j.dsr.2025.104595.
4. O’Malley, B.J., Schwing, P.T., Chernoch, S.K. et al. Thorium-234 as a tracer for deep-sea mining sediment plume deposition. Nat Commun 16, 10633 (2025).
5. Webber, A., Bento, J., Marsh, l., Downes, P., O’Malley, B., Ingels, J., and Clarke, M. Benthic plume generation from a production-scale model of polymetallic nodule collection. Unpublished presentation. Paper presented at the Underwater Minerals Conference in St. Petersburg, Florida, USA, November 2025.
6. Ibid.</sub>

Since at least 2020, concerns have been raised that sediment and seawater used to transport nodules to the surface could have significant impacts on pelagic communities when returned into the water column. However, these concerns have often failed to account for technological advancements in limiting the amount of sediment entering the vehicle in the first place.

During our 2022 mining test, our collector proved highly efficient at separating nodules from sediment, with 95–98% of sediment ejected behind the vehicle and the remaining 2–5% entering into the riser along with nodules and seawater. To assess the potential impacts of returning this fraction into the mid-water, we monitored the behaviour of the midwater plume using a Remotely Operated Vehicle and CTD sensors positioned at varying distances from the discharge outlet. By measuring areas inside and outside the plume, we were able to fully discern its extent. The plume formed a thin, stable “pancake” layer of about 150 meters thick that exhibited minimal vertical movement and diluted to background concentrations within two to four days.

These data were used to validate a multiphase plume model built with high-resolution computational fluid dynamics—the industry gold standard. A key finding of the model is that the rate at which the plume dilutes over larger distances is heavily influenced by turbulent mixing near the discharge outlet. During commercial operations, sediment concentrations returned to background levels within several kilometers. Dissolved metals were also found to dilute rapidly within 1.5km of the discharge outlet (1).

Based upon this model, the volume of water where sediment concentrations are significantly elevated over background levels is constrained to a small body of water close to the discharge outlet. Given the scale of the plume in relation to the vastness of the Pacific Ocean it is released into, the impacts are not expected to be significant.

_{1. Clarke, M., Bento, J., Marsh, L., Downes, P., Webber, A., and Udochi, S. Key findings of midwater plume modelling for commercial-scale polymetallic nodule collection operations in NORI-D. Paper presented at the Underwater Minerals Conference in St. Petersburg, Florida, USA, November 2025.}

Given the reliance of Pacific communities on domestic fishing industries, there was some understandable concern that dissolved metals released into the midwater column could bioaccumulate in fish tissues.

Fishing activity does take place across the Clarion Clipperton Zone. However, on account of its sheer remoteness, fishing activity recorded in areas currently under exploration represents less than 2% of total fishing hours on the high seas globally (1) and there is minimal overlap between seafloor fishing activities and areas considered for nodule collection, so direct interactions are expected to be rare and manageable (2).

Most fish live and breed in the top few hundred meters of the ocean, though some may dive to depths of up to 1,000 meters. This was confirmed on our NORI-D exploration area where independent scientists (3) and TMC (4) reported that pelagic biomass fell sharply from 1,000 meters onwards. To minimize vertical overlap with these more productive waters above, independent scientists advised that we discharge our return water at 2,000 meters—a standard expected to be adopted by all other contractors.

At such depths, dissolved metals contained in the midwater plume dilute rapidly, and our test mining data show that concentrations become indistinguishable from background within 1.5 kilometers of the point of discharge. Further, researchers at Australian universities and the national science agency, CSIRO, have assessed the potential bioavailability of dissolved metals for various species, finding that nodule collection is unlikely to result in the uptake of dissolved metals into fish tissues (5). Pelagic organisms at these depths are also no stranger to periodic spikes in dissolved metal concentrations with temporal fluctuations due to hydrothermal activity reported for the nearby East Pacific Rise.

<sub>1. International Seabed Authority. Technical Study 33: Potential Interactions between Fishing and Mineral Resource-Related Activities in Areas beyond National Jurisdiction: A Spatial Analysis. International Seabed Authority, 14 July 2023.
2. Earth Sciences New Zealand (formerly NIWA). Assessment of the Potential Impacts of Deep Seabed Mining on Pacific Island Fisheries. Earth Sciences New Zealand, Nov. 2016.
3. Drazen, J. C., Ferron, S., White, A., Popp, B., & Hatta, M. (2023a). Final Report: Characterization of the water column environment in relation to the testing of a prototype deep-sea mining vehicle in the eastern CCZ. Unpublished report submitted to TMC. University of Hawaii at Manoa.
4. TMC Environmental Impact Assessment. Campaign 8 data.
5. Pethybridge H, Fulton EA, Parr JM, Dunston PK, Rowden AA, Dambacher JM. 2025. Modelling ecological impacts of metal bioaccumulation from mid-water plume discharges. CSIRO Marine Laboratories, Hobart.</sub>

Our operations will generate some noise and light at the surface and seafloor. To understand and minimize potential impacts, our research team has collected several years of background acoustic data from in-field moorings and monitored both noise and light during test mining.

The main noise source from nodule collection is the surface production vessel, powered by diesel engines and dynamic positioning thrusters. Acoustic monitoring during our 2022 test showed that sound levels exceeding thresholds known to alter marine mammal behavior—based on U.S. agency NOAA’s standards—were confined to within a few kilometers of the vessel, a range comparable to other marine industries (1). Unlike many military and commercial operations, our vessels will not use sonar.

While whales and other cetaceans may migrate through our Clarion-Clipperton Zone (CCZ) contract areas, the region’s low surface productivity (2) makes it unlikely to serve as a major feeding or breeding ground. Nodule-collection operations may be audible to some marine species and could temporarily interfere with communication or navigation over short distances, though this same noise may also alert them to avoid contact. Several methods can be used to avoid or minimize noise impacts, including through noise abatement systems, trained marine mammal observers to minimize interaction with our activities, and microphones to monitor subsea vocalizations in real time (3).

Light emissions are similarly limited. The collector vehicle uses lights to illuminate its working area for visual monitoring, and the production vessel is the only surface light source. During test mining, the collector’s light footprint extended only tens of meters from the vehicle, while surface light from the ship penetrated no more than a few hundred meters into the upper water column.

<sub>1. TMC Environmental Impact Assessment.
2. Paulikas et al. (2020). Life cycle climate change impacts of producing battery metals from land ores versus deep-sea polymetallic nodules. Journal of Cleaner Production, 275. doi.org/10.1016/j.jclepro.2020.123822.
3. Polymetallic Nodule Research Alliance (2025). Will deep-sea mineral extraction affect cetaceans in the ocean?</sub>

We believe our exploration activities can be a primary driver of research and discovery when it comes to marine genetic resources. The Metals Company has already compiled an extensive library containing more than 20,000 preserved biological samples collected at 7-kilometre intervals. Sample collection and preservation is an integral part of our exploration program and we expect to collect many more samples as we explore new parts of our contract areas. We’re actively seeking academic partnerships to understand the genetic resource potential of this ever-expanding library.

In addition, a larger area in the Clarion Clipperton Zone has already been set aside for conservation than is currently under exploration. Contractors will also set aside further zones within their exploration areas and leave large areas untouched due to lower nodule abundances or where gradients are too steep for collectors to traverse, resulting in a mosaic of disturbed and untouched areas. These areas will remain protected from any future nodule collection operations and will be available for continued research on marine genetic resources, new genes, antibiotics and pharmaceuticals. Thanks to post-disturbance recovery studies, we also know that the abyssal ecosystem exhibits signs of recovery shortly after mining, increasing the likelihood that the genetic resources they contain will continue to be available for further scientific discovery.

More than four decades of international research—by government agencies and independent institutions— has shown that deep-sea ecosystems do recover from disturbance, typically over timescales ranging from a few years to several decades.

Since the 1970s, scientists have carried out 11 seafloor disturbance and test-mining studies, revisiting sites over 26 years to measure recovery. Reviews of these studies show that mobile and pelagic fauna generally recover within one year (1), while microbial communities—representing up to 60% of the affected biomass —are expected to recover within about 50 years (2).

The most recent of these studies, assessing a 1979 test using an Archimedes-screw-drive collector that disturbed up to 80 cm of sediment, demonstrated full recovery for sediment-dwelling macrofauna and microscopic foraminifera in both the track and heavily-sedimented areas (3), as well as re-colonization of the areas within the collector tracks by xenophyophores—giant, single-celled organisms that are known to promote biodiversity by providing hard-substrate habitat—suggesting the return of ecosystem complexity. Researchers also found no detectable, or even slightly positive, biological effects from sediment plumes.

Our own studies show that decades of technological innovation have resulted in a far smaller collector footprint which can accelerate ecosystem recovery. One year after our 2022 mining test, scientists observed that foraminifera directly within the collector tracks had recovered to 30% of pre-disturbance density and 50% of diversity, while microbes—which were expected to recover within 50 years based on assessments of earlier trials using legacy technologies—showed no significant change in either the tracks or areas influenced by sediment plumes. Changes in community composition—meaning changes in what species were present and in what proportion—were confined to millimeter-level sedimentation within 100 meters of the mined area (4). At greater distances, no measurable effects were detected. As reported in a 2025 review by independent academics comparing the impacts of 1970s trials to those of our own, integrating modern data and technological progress will be essential for the production of more realistic deep-sea mining impact assessments (5).

Long-term monitoring will continue to determine recovery timelines for species that require hard substrates such as nodules. However, revisits to the sites of trials conducted in the 1970s and today reported the presence of megafauna on left-behind nodules suggesting that intentionally not collecting a portion of the nodules—as all contractors intend to do—can support re-colonization of substrate-reliant organisms.

<sub>1. Jones, D. O., Kaiser, S., Sweetman, A. K., Smith, C. R., Menot, L., Vink, A.,Clark, M. R. (2017). Biological responses to disturbance from simulated deep-sea polymetallic nodule mining. PLoS ONE, 12(2), e0171750. doi:10.1371/journal.pone.0171750.
2. Vonnahme, T. R., Molari, M., Janssen, F., Wenzhofer, F., Haeckel, M., Titschack, J., & Boetius, A. (2010). Effects of a deep-sea mining experiment on seafloor microbial communities and functions after 26 years. Science Advances, 6(18). doi:10.1126/sciadv.aaz5922.
3. Jones, D.O.B., Arias, M.B., Van Audenhaege, L. et al. (2025) Long-term impact and biological recovery in a deep-sea mining track. Nature 642, 112–118. https://doi.org/10.1038/s41586-025-08921-3
4. TMC Environmental Impact Assessment
5. Ingels, J., Leduc, D., Ullmann, A. et al. Assessing mining impacts in the deep sea. Nat Ecol Evol 10, 172–174 (2026). https://doi.org/10.1038/s41559-025-02965-4</sub>

 

The Metals Company is committed to a transparent, scientific process and will continue to publish research based on its datasets while commissioning independent, peer-reviewed and reproducible research using these same data, before any commercial mining takes place. Dozens of peer-reviewed papers assessing the ecosystem and potential impacts of deep-sea mining have already been published, and we will continue to share this information with stakeholders prior to and following the commencement of commercial operations.

We commission research so that the international community can come to a fair, science-based conclusion on the effects of polymetallic nodule collection. The blind peer review process means that no outside group, including The Metals Company, can influence the research or publication process. No commercial collection can or will take place until rigorous, multiyear Environmental and Social Impact Assessments are conducted, vetted, reviewed and evaluated by the regulator. We invite curious readers to consult the various third-party LCAs we have commissioned for additional insights into the advantages of the nodule resource over its terrestrial equivalents.