Deep-Sea Mining: Balancing Green Transition Needs With Ocean Ecosystem Risks

The push for a green energy transition is creating demand for minerals, and attention is turning to the ocean floor as a potential source. But deep-sea mining isn’t without controversy. While concerns about environmental impact are significant, some researchers argue that, when compared to traditional land-based mining, extracting resources from the seabed could present a less damaging path – a claim that requires careful consideration given the limited understanding of deep-sea ecosystems.

Comparing Environmental Footprints

Saleem Ali, a distinguished professor of energy and the environment at the University of Delaware and advisor to the United Nations on critical metals, suggests that deep-sea mining deserves a place in the conversation surrounding sustainable resource acquisition. Ali co-authored a 2022 analysis that directly compared the waste products of terrestrial mining operations with those anticipated from harvesting polymetallic nodules from the seabed. The study, funded by The Metals Company, examined the impact of mine tailings on water quality and biodiversity on land, and contrasted that with the potential pollution from sediment plumes created by deep-sea harvesting machines. (Ali clarifies he has not received direct funding from The Metals Company.)

The analysis indicates that both methods of mining will inevitably affect biodiversity. However, the study suggests that deep-sea mining *could* result in less overall waste and fewer direct risks to local communities than land-based mining. This conclusion, however, is heavily caveated. The researchers emphasize “substantial uncertainty” regarding the long-term effects of sediment plumes on deep-sea life. The plumes, created when harvesting machines disturb the seafloor, could smother organisms and disrupt feeding habits.

Ali’s position isn’t an endorsement of deep-sea mining, but rather a call for its inclusion in a broader assessment of difficult choices. “I’m not saying that we should go ahead with it. I’m saying that it deserves to be considered in this broad context of very difficult choices we have to make,” he says.

Data Gaps and the Require for Regulation

The International Seabed Authority (ISA), the intergovernmental organization responsible for regulating deep-sea mining, has been collecting data on the deep ocean for over three decades. Ali believes this existing data should be sufficient to establish rules and regulations, even in the absence of complete certainty about long-term impacts. However, other scientists argue that the current data is insufficient to make informed decisions.

Anna Metaxas, a deep-sea ecologist at Dalhousie University in Canada, emphasizes the need for caution. She participated in a 2025 overview of the potential impacts of mining on the deep-ocean ecosystem published in the Annual Review of Environment and Resources. Metaxas is too involved with the Deep-Ocean Stewardship Initiative, a nonprofit network dedicated to informing deep-sea policy. She previously led a project aimed at comparing the environmental impacts of land and seabed mining, but in 2024, she and her co-authors concluded that current data is too limited to draw meaningful comparisons.

“Our knowledge gaps are really large,” Metaxas states.

Understanding the Clarion-Clipperton Zone

Much of the current focus is on the Clarion-Clipperton Zone (CCZ), a vast area in the Pacific Ocean rich in polymetallic nodules – potato-sized concretions containing valuable metals like nickel, cobalt, and manganese. These metals are crucial for manufacturing batteries used in electric vehicles and energy storage systems. The CCZ is also home to a unique and poorly understood ecosystem, as illustrated in images captured by research vessels (see image caption: The seafloor of 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. (bottom right), and starfish (bottom left). The biology and ecology of these depths remain poorly understood, making it hard to know what the ecological impacts of deep-sea mining would be. Credit: ROV TEAM / GEOMAR (CC-BY 4.0)).

Matthias Haeckel, a marine biogeochemist at the GEOMAR Helmholtz Centre for Ocean Research in Kiel, Germany, highlights the challenges of regulating mining in an environment where the basic biology is still largely unknown. Haeckel is part of a team of experts tasked by the ISA to develop monitoring and assessment standards for mining impacts. Their work focuses on assessing toxicity from heavy metals, the effects of sediment plumes, and the impact of underwater noise and light pollution. They are expected to submit initial guidelines later in 2026.

The Regulatory Landscape and Industry Pressure

The ISA Council convened in Jamaica in early March 2026, and will meet again in July, to debate and potentially adopt mining regulations. The Metals Company, a leading proponent of deep-sea mining, is awaiting approval from the United States to begin commercial mining in the CCZ. The company anticipates receiving a permit by the complete of 2026 and commencing operations shortly thereafter.

Meanwhile, scientists are racing to gather more data. Haeckel is leading the MiningImpact project, which will revisit research sites previously monitored during mining tests conducted by Global Sea Mineral Resources, a subsidiary of the Belgian company DEME, in 2021. The project aims to assess the ecosystem’s recovery five years after the initial disturbance and to improve understanding of the abyssal environment.

“The Clarion-Clipperton Zone is a large area, and there are still many, many open questions,” Haeckel says. “How could we properly regulate mining when we hardly know what creatures live down there, or how they interact?”

The debate over deep-sea mining underscores the complex trade-offs inherent in the pursuit of a sustainable future. Balancing the demand for critical minerals with the need to protect fragile and largely unknown ecosystems will require careful consideration, robust scientific research, and international cooperation.

Ongoing Research and Future Assessments

The immediate next steps involve the ISA finalizing mining regulations and the continued collection of scientific data. The MiningImpact project, along with other ongoing research initiatives, will provide crucial insights into the long-term effects of deep-sea disturbance. The effectiveness of the ISA’s regulatory framework will depend on its ability to adapt to new information and address the significant uncertainties that remain. Further studies are planned to investigate the resilience of deep-sea organisms and the potential for ecosystem recovery following mining activities.