Saleem Ali, an environmental systems scientist at the University of Delaware who researches and advises the United Nations on critical metals, says deep-sea mining should be part of the green transition discussion. He co-authored it 2022 analysisFunded by The Metals Company, it compared mining waste from surface deposits with seabed resources. (Ali says he never received direct funding from The Metals Company.) For example, the analysis looked at the impact of surface mining waste on water pollution and local biodiversity, and the pollution expected from nodule mining, such as the dumping of seabed sediment into the water column by harvesters. This suggests that both mining activities will affect biodiversity, but deep-sea mining may result in less waste and less risk to communities than surface mining. However, the study cautions that its results are limited by “substantial uncertainty” about the impacts of the storks.
Ali adds that the International Seabed Organization has been collecting data for at least 30 years, which should be enough to develop rules and regulations to govern seabed mining, even if it’s unclear what the long-term effects are and whether the environmental impacts will be better or worse than onshore mining.
“I’m not saying we should go ahead with it. I’m saying it deserves to be considered in this broader context of the very difficult choices we have to make.”
But opponents calling for moratoriums or bans point out that the same study that The Metals Company cited as evidence of a rapid recovery ultimately came to more pessimistic conclusions than its data suggests. “The impacts of polymetallic nodule mining are likely to be long-lasting,” the authors wrote, and the analysis “indicates significant adverse biological effects of seabed nodule mining, even in small-scale test mining experiments.” Scientists worry that deep-sea organisms, adapted to living in a dark, quiet and sparsely populated environment, may not be able to cope well with noise and light disturbances from mining. Organisms will also be exposed to toxic metals and sediment plumes that can interfere with feeding and breathing. The Metals Company did not respond to multiple requests for comment.
The sea floor of the Clarion-Clipperton Zone is home to many creatures, some of which are shown here: anemone (top left), sea cucumber, Psychropotes longicauda (top right), sea urchin Plesiodiadema sp. (lower right) and starfish (lower left). The biology and ecology of these depths are still poorly understood, and it is difficult to know what the environmental impacts of deep sea mining will be.
Credit: ROV TEAM / GEOMAR (CC-BY 4.0)
The sea floor of the Clarion-Clipperton Zone is home to many creatures, some of which are shown here: anemone (top left), sea cucumber, Psychropotes longicauda (top right), sea urchin Plesiodiadema sp. (lower right) and starfish (lower left). The biology and ecology of these depths are still poorly understood, and it is difficult to know what the environmental impacts of deep sea mining will be.
Credit: ROV TEAM / GEOMAR (CC-BY 4.0)
Anna Metaxas, a deep-sea ecologist at Canada’s Dalhousie University and co-author of the 2025 review, says that given these unknowns, there is no need to rush into mining regulations. potential impacts of mining on the deep ocean ecosystem in the year Annual Review of Environment and Resources. Metaxas participates in the Deep-Ocean Stewardship Initiative, a non-profit international network of experts to inform deep-sea policy and management. He says he previously led a project with experts in onshore and deep-sea mining to develop a framework for environmental comparisons of onshore and subsea mining. But in 2024 he and his co-authors concluded that the data are currently too scarce to do so.
“Our knowledge gaps are really big,” said Matthias Haeckel, a marine biogeochemist at the GEOMAR Helmholtz Center for Ocean Research in Kiel, Germany. He is part of a group of 30 researchers and technical experts tasked by the International Seabed Organization in 2024 to develop the values needed to monitor and assess the impacts of mining. The group looked at toxicities such as heavy metals, turbidity from sediments dumped by harvesters, underwater noise and light pollution. They are expected to present the first draft of standards and guidelines later this year.
Looking for answers – and soon
The International Seabed Authority Board – its executive body – met in Jamaica in early March and will do so again in July to discuss and possibly adopt mining regulations. The Metals Company is still awaiting a nod from the United States to begin commercial mining operations in the Clarion-Clipperton Zone. But he said he expects to receive permits by the end of this year and start mining shortly thereafter.
Meanwhile, scientists like Heckel are scrambling to launch additional research cruises to provide critical data that will inform decisions about the future of seabed mining and the mining code. Hekkel is leading a European project called MiningImpact, which will return later this year to research areas where it is monitoring some of the mining trials by Global Sea Mineral Resources, a subsidiary of Belgium’s DEME, in 2021. The third phase of MiningImpact aims to see how the ecosystem fared over five years and to promote further understanding of the ecology of life deep within the abyss.
“The Clarion-Clipperton zone is a large area, and there are still many, many open questions,” Heckel says. He wonders how mining in the area can be properly regulated when scientists still barely know what creatures live there or how they interact.
