Environmental impacts of deep-sea mining - from scientific research to policy recommendations

The abyssal seabed harbours minerals, i.e. polymetallic nodules, massive sulphides, and cobalt-rich ferromanganese crusts, which are rich in metals that are critical for the technologies of our energy and mobility transition and digitalization. As a consequence, interest in deep-seabed mining has been growing over the last decade, and regulations for the exploitation of these resources are being developed on international and national level. While extracting metals from deep-sea ores may contribute to the desired overall reduction of our CO₂ emissions, it will certainly introduce a new environmental threat to our oceans that calls for effective protection and the precautionary approach defined in UNCLOS.

The research of the JPI Oceans project MiningImpact (miningimpact.geomar.de) has demonstrated that abyssal ecosystems show unrivalled high biodiversity in combination with high spatial and temporal variability of faunal populations and environmental variables. Our results indicate that environmental impacts from future deep-sea mining operations will be severe and will last for centuries to millennia. Our independent scientific monitoring of a recent industrial test of mining technology in the Clarion-Clipperton-Zone of the Eastern Equatorial Pacific shows that polymetallic nodule mining will not only remove the metal ore, which forms a specific habitat for a rich benthic fauna, but the entire biologically active surface layer of the seafloor, which forms the basis of the abyssal food web. In addition, the produced suspended particle plume will also blanket the benthic ecosystem outside the mined areas. Larger-scale consequences are still uncertain due to the largely unknown species connectivity and our limited understanding of ecosystem structure and functions. Hence, at the anticipated scale of impact of several hundreds of square kilometres per year for each nodule mining operation, careful and adaptive spatial planning of mining operations on regional and even global scale is required. Conservation areas must be set aside that closely match ecosystem characteristics in mined areas, and effective ecological indicators and threshold values indicative of harmful effects to the marine environment need to be defined. Transparent monitoring of mining operations is needed to ensure compliance with high environmental standards to protect the marine environment from serious harm. 

This presentation will summarize the observed immediate and expected long-term consequences of deep-sea mining operations and will discuss how independent scientific studies can inform regulatory processes, such as the development of the Mining Code of the International Seabed Authority.