Opinion: The extent of the unknown: Understanding the risks and exploring the alternatives to Deep-Seabed Mining
By Marguerite Culot – Biodiversity Expert at Caisse des Dépôts Group and Co-chair of the FfB Foundation Target Setting working group
The ocean is the largest ecosystem on Earth: It covers 71% of Earth’s surface and comprises 90% of the biosphere. It provides food security for over 3 billion people, enables the transportation of over 80% of global goods, and hosts sea cables carrying 98% of international Internet traffic. The OECD describes it as a powerful driver of global growth, with the Blue Economy expected to triple in value by 2050. It is also the planet’s largest carbon sink, generating 50% of the oxygen we need, absorbing 30% of all carbon dioxide emissions, and capturing 90% of the excess heat generated by these emissions. As such, it is a vital buffer against the impacts of climate change.
However, the ocean’s health and economy are at risk from deep-seabed mining (DSM), an activity that could cause widespread, irreversible damage to sensitive and largely unexplored ecosystems. This op-ed presents a financial institution’s perspective on the significant risks associated with DSM and the alternative strategies that merit further exploration.
Understanding risks – what is at stake with Deep-Seabed Mining (DSM)?
Deep-seabed minerals are found in ecosystems inhabited by diverse and fragile marine species. DSM could severely disrupt the vast array of ecosystems, habitats, and species that exist in a delicate balance in the deep ocean. Moreover, the debris generated by deep-sea drilling could harm habitats of marine species for hundreds of metres. Yet what is most concerning is the sheer extent of our knowledge gaps. Scientists do not know how the disturbances in the deep-sea could affect biological processes along the entire column of water.
To date, only 0.001% of the deep seabed has been explored. New species are still being discovered, and groundbreaking findings – such as deep-sea organisms producing “dark oxygen” – hold the potential to reshape our understanding of life on Earth.
Interfering with deep-sea processes could trigger cascading effects, including disruption of the marine food web and degradation of the ocean’s carbon storage capacity. Complex physical processes essential for the maintenance of life on Earth are underpinned by healthy, functioning deep-sea ecosystems. In addition to environmental risks, the social impacts of DSM could be significant. The deep seabed is a heritage of mankind, and its benefits should be equitably shared. Impacts cross jurisdictional and ecological boundaries, and a misstep could have serious risks for us all.
The One Ocean Science Congress 2025 has published recommendations in parallel to UNOC 2025. These include: “Pause harmful seabed uses and expand deep-sea knowledge for sustainability”. This highlights the urgent need to prioritise scientific research before proceeding.
Exploring alternatives: Do we need deep-seabed minerals?
Despite claims that DSM is essential for securing critical minerals required for the economic transition to meet climate change goals, current evidence does not support this. Instead, we may be missing the right strategies and policies for the energy and digital transitions. Should we accept running into the wall by scraping the abyssal depths?
Scientists often note that we know more about the moon than about the ocean. It is irresponsible to advance an activity with such potentially catastrophic consequences without first exhausting safer, more sustainable alternatives.
The Energy Transitions Commission (2023) found that circular economy strategies could fully close projected supply gaps for copper and nickel, and significantly narrow them for lithium, cobalt, and neodymium by 2030. These strategies include recycling and “urban mining” of minerals from used electronics, batteries, and industrial waste—methods that not only reduce demand for virgin materials but also help solve the growing problem of electronic waste.
In addition, policy shifts promoting energy efficiency and behavioural changes could moderate resource demand. Land-based mining can be made more sustainable through technological improvements and better governance. Emerging innovations such as sodium-ion batteries also offer viable pathways to reduce reliance on rare deep-sea minerals.
Strengthening marine protections is essential. Governments must uphold commitments under the Global Biodiversity Framework and the UN High Seas Treaty to safeguard marine ecosystems.
Next steps: applying the precautionary principle
The current work of the International Seabed Authority (ISA) on developing rules, regulations, and procedures (RRPs) for DSM will be key to ensuring the best possible social and environmental practices if the activity becomes effective in the future. However, an entire sustainability framework needs to be developed – a process that took decades for terrestrial mining. Effective oversight of DSM will be even more difficult due to the remoteness and complexity of the deep-sea environment.
From an economic standpoint, DSM is far from viable. In 2024, Planet Tracker estimated that the industry would deliver an average return on invested capital of -2%, meaning it would fail to cover its own capital costs. This further undermines the rationale for fast-tracking DSM.
In that context, financial institutions are expressing concern about rushing into an activity that could lead to significant policy, regulatory, and reputational risks. A growing number are developing policies and actions regarding DSM. As an example, the Caisse des Dépôts Group adopted a Nature Policy in May 2025 which commits its financial institutions (the Asset Owner of the Caisse des Dépôts, CNP Assurances, LBP, LBPAM) to exclude financing or investing in DSM pure players as well as financing DSM projects.
The extent of the unknown surrounding DSM means that there is a crucial need to comprehensively understand the scale of the risks posed by this activity. For governments to issue DSM permits without further investigation would be in direct contradiction to the precautionary principle.
In conclusion, to avoid long-term damage to our world, we must approach untapped industries like DSM with caution. Our efforts should focus on supporting the transition of global systems into a future where we co-exist in harmony with the ocean. Embracing the large-scale risks that DSM poses to the Earth’s systems cannot be considered possible until its alternatives are fully explored.
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Further information:
FfB Global Financial Institutions Statement to Governments on Deep Seabed Mining (DSM), open to signature until 1 July 2025.