Metal mining on land versus the ocean in the context of the current Biodiversity Crisis

Opening the ocean frontier will neither halt nor reduce terrestrial mining for nickel and cobalt. Extraction will continue on land, with associated biodiversity loss¹⁵. Rather than reducing environmental pressures on land, seabed mining would open an additional realm of ecosystem degradation. Likely ecosystem outcomes are well iterated (e.g., ref. ¹¹), but a chronic lack of knowledge of deep-sea biodiversity and ecosystem functions, such as their role in modulating global nutrient and carbon cycles, limits predictions of broader mining impacts¹⁶.

Information is inadequate to compare impacts on ecosystem integrity from land versus seabed mining– the biomes are too disparate¹⁷. No comprehensive and systematic data exist for the impacts of nickel or cobalt mining, and predictions for seabed mining are poorly constrained estimates¹⁷. One crude measure is habitat loss: nodule mining will have a spatial impact orders of magnitude greater than all active terrestrial mines combined, including secondary disturbances from the infrastructure and mining activities. The estimated direct habitat loss in nodule extraction is 508,000 km² of seafloor for initial contracts¹⁸. These operations will likely affect adjacent (seafloor and water column) habitats further extending ecosystem damage¹⁹. In contrast, the total current global land area directly affected by ~6000 mines active from 2000 to 2017 is 57,277 km², of which nickel and cobalt mines encompass about 3430 km^2 20. It is unlikely that environmental outcomes will be better in the large tracts of poorly accessible seabed. Our history of exploitation before understanding the environmental consequences is long and alarmingly duplicative (e.g., fisheries collapse, aquifer drawdown, etc.).

Environmental impact assessment is typically underpinned by the application of the mitigation hierarchy. This principle, supported by reliable data and evidence, can reduce environmental impacts through a tiered approach of avoidance, minimization, restoration, and offsetting – but strict adherence is necessary. Mining is a destructive activity that removes and/or dislocates the substratum underlying the ecosystem. Impacts on biodiversity can be avoided and minimized through careful project design and, where needed, strict no-go zones. Regulators must ensure that miners proceed only after all reasonable options to avoid impacts are exhausted. Attempts to restore complex ecosystems following severe disturbance have low success on land where only a few mines have met international restoration standards²¹. While restoration, and the less ambitious rehabilitation, are difficult, a focus on biodiversity revitalization is critical. Monitoring and biodiversity assessment require several decades following mine closure²². The terrestrial mining industry and its regulators must prioritize research demonstrating that recovery goals are achievable and resilient, especially considering the changing climate. Offsetting strategies commonly rely upon the protection of threatened like-for-like habitats and/or upon restoration of degraded land to achieve a condition similar to the disturbed ecosystem. In the latter case, a net biodiversity loss occurs initially until overall benefits and gains are achieved²³. Moreover, governance mechanisms must ensure those benefits persist once the mine closes or the mining company changes hands. Clear successes of offsets in mining are hard to demonstrate^23,24.

In contrast, the applicability of the mitigation hierarchy to seabed mining is fundamentally compromised. First, data and models are inadequate to support the ‘avoid’ principle and ensure that mining does not impact sensitive ecosystems. Second, ecological restoration in the deep sea is an impossible goal as unique, ancient substratum and habitat features cannot be replaced. Third, valid offset opportunities do not exist for the deep ocean as “out-of-kind” offsets will not achieve No-Net-Loss²⁵. Thus, only minimization remains. A self-reporting system at the ISA is unlikely to achieve environmental management excellence²⁶. Given access challenges to mine sites thousands of meters underwater and far out to sea, there will be a strong reliance on self-monitoring by miners. There is no report of developments of full-time monitoring tools capable of communicating in near real-time over such immense seabed areas. When environmental harm is detected, lengthy response times and a dearth of biodiversity-based protocols would limit successful mitigation, even if technologically possible.

Before advancing deep-sea exploitation, much can be learned from past terrestrial mining, especially for reforming mining regimes. Recurrent ecological disasters highlight limited capabilities to model or mitigate the biodiversity impacts of mining on most terrestrial and freshwater ecosystems. A poor record of satisfactory terrestrial mine closures around the world portends the path ahead for the deep sea²⁷. If such is the state of our knowledge and practice despite long recognizing the impacts of terrestrial mining, there is little basis to expect better outcomes when mining the remote seabed. The status quo of poor biodiversity outcomes from terrestrial mining cannot continue. However, it also cannot be the justification for seabed mining as a more environmentally “sustainable” source of needed metals. It is a pivotal moment now for miners, regulators and scientists to reflect on past successes and failures to safeguard biodiversity on land. Here, healthier ecosystems can build upon the foundations of terrestrial biodiversity protection and recovery, including better water, waste, and tailings management.

Most terrestrial industry and regulatory agencies have a large gap to close between current practices and actions to reduce biodiversity loss. An obligatory and strong code of practice applied consistently across jurisdictions in land-based producer countries, that features rigorous ecosystem assessment, monitoring, and protection would narrow that gap. Economic returns from metal extraction might diminish, but consumer and investor focus on sustainability can drive the market in favor of better environmental practices. Sustained services from intact ecosystem integrity will benefit humans. Scrupulous and enduring oversight by regulators will minimize biodiversity impact, including avoidance of mining where conservation values are high. A key area for improvement lies in the planning and execution of post-closure activities that mediate ecosystem harm from mining. Initial financial guarantees that reflect true costs for mine and tailings site remediation and rehabilitation are necessary. Impact monitoring and reporting during mining can help the miner mitigate problems before they become costly. Comprehensive closure plans, regularly updated, will also maintain awareness and ongoing solutions. Requirements for long-term monitoring with necessary interventions will ensure better biodiversity outcomes and a better public profile.

It is clear we know what should be done for terrestrial mining. Why it does not happen in practice is less clear. We lack internationally agreed and legally binding standards for the environmental management of mining. Regimes vary greatly among jurisdictions usually featuring voluntary or industry-led guidelines and standards; such protocols are often ineffective with few requirements for monitoring and adaptation, and lack third-party verification. A multilateral focus on the mining sector may bring about harmonized standards with better environmental outcomes. The Initiative for Responsible Mining Assurance (IRMA) Standard provides requirements for both existing and new mines that include guidelines to maintain biodiversity and ecosystem services²⁸. Investors, manufacturers, and consumers should urge the industry to join such initiatives with the intent to meet these standards – ultimately, the consumer pays the price for biodiversity declines. Finally, States must take the lead to reform and implement national laws in a way that respects their international commitments to the biodiversity crisis. Relevant action includes strengthening mining laws in producer countries but also encompasses ocean governance and sustainable consumption sectors globally.

A double win is possible: (i) implement a precautionary pause on the commencement of deep seabed mining²⁹ while increasing research efforts to understand the ecosystem costs and (ii) improve mining practices and regulations that affect the terrestrial environment. We, the global community, cannot afford, in ignorance, to advance activities that damage ecosystems of the deep ocean, while continuing to erode land-based counterparts. Solutions to address nickel and cobalt supply include increased efficiency and sustainability in metal extraction from mines, re-mining of tailings, novel technologies in battery chemistry, and expanded recycling and urban mining. Improved public transport and consumer awareness of (or surcharge on) the costs to biodiversity can reduce electric vehicle demand. Ultimately, policy must involve a careful accounting of the full costs to the planet, its biodiversity, and its people when enabling mine development. The history of terrestrial mining sets a very low bar for environmental outcomes; it is little wonder that proponents of seabed mining use it as a measure for claims that they can do better. Yet, this new, complex form of mining is bound to follow a similar, if not worse, path toward poor environmental outcomes.