Researchers around the world are racing to get a fuller picture of the ecological impacts of mining the deep seabeds of the Pacific Ocean for valuable minerals. What’s been done and what do we know so far?
Deep sea mining involves removing potato-sized “nodules” from the bottom of the ocean floor. These nodules are full of metals, like cobalt and nickel, which are essential for electric vehicle batteries and other green technologies.
The SMC asked experts to provide background information on the research behind the ecological impact of deep sea mining.
Professor James J. Bell, Professor of Marine Biology, Victoria University of Wellington, comments:
1. There’s been a recent wave of research on deep sea mining. Has there been a particular long-term study or research initiative that’s been especially helpful to inform our understanding of its ecological impact? For example, what have we learned, or are we still learning, from the DISCOL project?
“Aside from the physical impacts of habitat removal, one of the key areas of research has been understanding the effects of plumes generated by mining activities. There is much debate about how far these plumes may travel and what impacts they may have on marine organisms.
“Recent studies have shown that plumes generated from simulated mining activities can travel several kilometres from the mining site, forming dense clouds of sediment in the water that eventually settle back onto the seafloor. For example, a recent study by the multi-institutional European project MiningImpact in the Clarion-Clipperton Zone (CCZ)—a nodule-rich area between Hawaii and Mexico—found that plumes could travel up to 4 km from mining sites. Even more concerning was the high level of sediment deposition over the seabed within 100 meters of the mining site, where essentially all nodules and associated organisms were killed.
“This study has also been monitoring the recovery of these areas over several years, but little recovery has been observed. These findings highlight concerns about the long-term impacts of deep-sea mining, as we have limited long-term data to predict what recovery might look like. However, the DIS-turbance and re-COL-onization (DISCOL) experiment, conducted in 1989, may offer some insights. This study initially monitored the impacts of a simulated seabed disturbance for only a few years, but when researchers returned 26 years later, the scars from the mining were still evident—underscoring the potential long-term impacts of deep-sea mining.”
2. Why is this kind of research so difficult?
“Deep-sea environments are, by their very nature, extremely difficult to access. This is partly why we know far less about them compared to most other marine ecosystems—and even less about how they will be impacted by mining activities. Accessing these deep-water environments is very expensive and requires manned submersibles, Remotely Operated Vehicles (ROVs), or Autonomous Underwater Vehicles (AUVs). Operating these machines generally requires large vessels and extensive support systems, which means there are few studies directly examining the impacts of deep-sea mining.
“In addition, it is very difficult to bring many deep-sea organisms to the surface. They are adapted to the high pressures of deep water and may not function properly at surface pressures unless kept in a pressurized chamber. This makes laboratory studies on plume impacts particularly challenging.”
3. What upcoming data or research projects are researchers especially excited to hear about in the near future? What questions does the research community hope they will answer?
“I think one of the key areas of research is the ability to predict the nature and behaviour of the plumes generated by these mining activities. With sufficient data for a particular area, it should be possible to predict with some accuracy where the plume will move and where sediment will be deposited. More informed decisions could then be made about the potential impacts.
“While there are several studies demonstrating the negative effects of plumes and sediment more generally, there is limited data on recovery times, which could be very long given the typically stable nature of deep-water communities. Unfortunately, this data is very difficult to obtain, as it takes time!
“However, just this month, further research funding has been allocated in Norway to continue with MiningImpact3. This is an international research project focusing on polymetallic nodule fields in the Pacific and seafloor massive sulfides in the Atlantic. The third phase examines the long-term effects of test mining conducted in 2021. As studies like these continue, we will gain greater insight not only into the impacts of deep-sea mining but also into recovery times.”
Conflict of interest statement: “I receive funding from Department of Conservation, George Mason Charitable Trust, Royal Society of New Zealand Marsden Fund, Greater Wellington regional council, and Environment Southland.”
Dr Stuart Minchin, Director-General, The Pacific Community (SPC), comments:
“SPC’s work on deep sea minerals is grounded in scientific research, data collection, and capacity building. Our primary role is to support our member countries by providing technical and scientific advice to inform their decision-making processes. Through capacity-building initiatives and technical assistance, SPC helps ensure that countries have the tools needed to develop policies and governance frameworks that align with best scientific practices and international standards. Our commitment to environmental protection and sustainability is fundamental, as we provide data to support the responsible management of marine ecosystems. By fostering science-based discussions, SPC respects the sovereignty of each member country in determining its approach to deep sea minerals.
“The International Tribunal for the Law of the Sea’s Advisory Opinion of 1 February 2011 highlighted that the precautionary approach is an integral part of the general obligation of due diligence. This means that in the face of scientific uncertainty, states should take appropriate measures to assess and mitigate potential environmental risks. SPC contributes to this process by providing member countries with scientific data and technical expertise to support risk assessment and informed decision-making in line with international best practices.”
“A foundational aspect of marine resource governance is the clear delineation of maritime zones. Understanding the outer limits of a state’s maritime space provides legal clarity for governance, resource management, and enforcement. This is particularly relevant in light of climate change-related sea level rise. Domestication of the 2021 PIF Maritime Zones Declaration into national law and the finalisation of outstanding maritime boundaries remain key priorities for many Pacific Island countries.”
“For more than a decade, SPC has contributed to deep sea minerals research and governance support. Under the SPC-EU DSM Project (2010-2016), SPC developed regional frameworks and guidelines, assisted Pacific Island countries in strengthening national DSM policies and legislation, conducted stakeholder consultations, and carried out cost-benefit analyses. SPC has also provided technical and legal advisory support, conducted training workshops, and fostered partnerships with regional and international organisations. SPC recognises that some areas of deep-sea mineral research and governance require specialised expertise beyond our current capacity. In such cases, we collaborate with our regional and international partners to access the necessary scientific and technical support. This ensures that the advice provided to our member countries is informed by the best available knowledge and global best practices. These efforts are part of our broader mission to provide member states with the best available scientific and technical information on marine resources.”
Conflict of interest statement: “Dr. Stuart Minchin is the Director-General of The Pacific Community (SPC). The work on DSM is embedded within SPC’s Geoscience, Energy and Maritime (GEM) Division. The GEM Division, guided by the SPC Strategic Plan 2022-2031 and the GEM Division Business Plan 2023-2027, focuses on providing scientific and technical support to SPC member countries. Dr. Minchin’s role involves overseeing the strategic direction and ensuring that the work aligns with SPC’s mandate and values. SPC remains committed to transparency, good governance, and the scientific integrity of its work.”