Last month, I led a team in the thrilling discovery of a deep-sea octopus nursery on underwater mountains, only the fourth such location known in the world. It was incredible to witness octopuses being born, their tiny pink tentacles springing to life. Worryingly, any day now, the International Seabed Authority (ISA) could green-light mining for metals and rare-earth elements in habitats such as these.
Between 10 and 21 July, ISA’s council met in Kingston, Jamaica, to hash out a code of rules for deep-sea mining in international waters. Interest in exploiting the deep sea is exploding thanks to its deposits of cobalt, nickel, rare-earth elements and other metals that are used in key green-energy technologies such as electric-vehicle batteries, solar panels and wind-turbine magnets. ISA, an intergovernmental body tasked by the United Nations with regulating deep-sea mining while ensuring the protection of the marine environment, missed a 9 July deadline to finish the code. Now, commercial mining applications could be submitted to ISA even though the code is not complete, which raises many legal issues that its council is rushing to try to resolve.
Deep-sea mining could soon be approved — how bad is it?
The code would be a legally binding document defining: how environmental-impact assessments must be done; the thresholds for harm to the marine environment; how inspection, monitoring and enforcement would occur; and how the benefits of mining would be shared equally between countries.
In my view, it is impossible to effectively protect, monitor for harm or restore these ecosystems without a basic understanding of their biology. Some of the sought-after minerals are found in lumps called nodules that form on the sea floor over millions of years. Mining them currently requires scraping large tracts of sea bed, which is destructive and indiscriminate.
For the two weeks of the ISA meeting, I fielded hundreds of daily messages while providing expert scientific guidance to delegations in my capacity as a contributor to the Deep-Ocean Stewardship Initiative.
I told the delegations that the world knows too little about deep-sea ecosystems to judge what rules would ensure their protection. It is difficult to even convey the immense scale of our knowledge gaps. Deep-sea corals — like trees on land — are keystone species in their habitats, providing crucial structure for other forms of life. Scientists don’t really know how these corals reproduce: spawning has never been documented. How can we restore a baseline that we have never observed? We need research covering at least ten years for each habitat to be able to make evidence-based decisions.
Mining will affect animals, such as corals, that are attached to the sea bed and microorganisms that provide crucial ecosystem services, such as carbon fixation and nutrient recycling. It will affect the entire water column above the sea floor, generating plumes of debris as well as noise and light pollution that could affect migratory species, including commercially important animals such as tuna. The deep sea is a repository for immense genetic diversity that could yield new scientific insights.
There is irreplaceable scientific value in some deep-sea ecosystems, such as the Lost City field of hydrothermal vents near the Mid-Atlantic Ridge, with its towering ‘cathedrals’ of carbonates. Its unique chemistry and microbiology yield clues about how life evolved on Earth and whether it might exist on other planets.
The global fight for critical minerals is costly and damaging
Restoration is commonly used in land-based mining to make up for harm caused. But the deep sea operates on a profoundly slower timescale than ecosystems on land, and there is no evidence that restoration would work as a mitigation strategy. Forests can be replanted, but there is no current evidence that deep-sea habitats could be repaired on human timescales after extensive damage. In fact, studies suggest that natural restoration of deep-sea ecosystems and their services will probably take thousands to millions of years.
Proponents of deep-sea mining argue that it causes less environmental damage and has fewer human impacts than does mining on land, but it is not yet possible to know the effects on the deep sea, let alone compare them with those of land-based mining. Besides, this argument seems a false dichotomy to me. Deep-sea mining will not replace mining on land — both types will probably continue.
I think that the urgent need for critical minerals should further spur innovation instead of leading to irreplaceable deep-sea ecosystems being wiped out. Nations should boost investment in battery chemistry research, which shows promise for reducing the need for these materials, and in reuse and reclamation programmes for the metals already extracted that are currently destined to sit in landfill.
It’s not just hundreds of scientists around the world — including me — who are calling to pause mining in the deep sea because of the lack of understanding of these ecosystems. Twenty countries support a pause or moratorium, including Brazil, Canada, Germany and New Zealand, and France supports a ban. Major companies including Google, Microsoft, BMW and Volkswagen have pledged not to buy or finance deep-sea minerals until the supply chain meets environmental, social and governance standards.
When I was an undergraduate student two decades ago, deep-sea mining was discussed as if it were science fiction, not likely to happen in my lifetime. I hope it stays in the realm of fiction. We have much better options for the future of our society and our planet.
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I am vice-president for research at the independent, non-profit organization Bigelow Laboratory for Ocean Sciences, where I also serve as associate director of the Crustal Ocean Biosphere Research Accelerator (COBRA). I am also an expert contributor to the Deep-Ocean Stewardship Initiative (DOSI) global network, which acts as an official observer at meetings of the International Seabed Authority (ISA) to inform the ISA about likely environmental impacts of deep-sea mining. My perspective in this article is my own and does not necessarily represent the positions of my affiliated institutions.