Deep-Sea Mining, Why Not?

The world appears to be on the verge of commercial deep-sea mining for polymetallic nodules in the Clayton-Clipperton Zone in the Pacific Ocean. Access to critical materials, needed for the energy transition to combat climate change, is the main argument presented to start this mining.

This paper philosophically reviews the prospect of deep-sea mining. Based on recent scientific publications, it addresses, on the one hand, whether we know enough to manage the environmental risk. On the other hand it assesses the actual need for critical materials and the potential benefits to mankind. Finally risks and benefits of deep-sea mining are weighed to argue why we should not.

Recent development and testing of mining techniques, are leading to increased knowledge of the pressures to the environment. However, reviewing the general status of deep ocean science, I conclude that knowledge of what is at risk, biodiversity and most notably the biotic situation, remains poor. Hence the capability to understand, forecast and assess the impact of mining pressures is also poor. Failing such knowledge, we do not know how effective the existing approach to environmental management is.

The potential benefit of deep-sea mining, provision of critical materials for the energy transition, related to current developments is unconvincing. Developments in clean energy technology and potential for circular use are reducing the need for the nickel and cadmium that polymetallic nodules typically provide. Remaining need can be met by conventional mining if users are prepared to enter into long-term agreements. Economic benefits accrued by exploitation of the CCZ are unlikely to provide a material benefit to mankind and are more likely to damage existing mining industries by creating an oversupply. Deep-sea mining thus fails the objectives of the UN Convention of the Law of the Sea to “benefit mankind as a whole” (UN, 1982, art. 140).

In summary I conclude that deep-sea mining is not needed for the energy transition and will not “benefit mankind as a whole”. Given the unquantified risk to the environment, the precautionary approach of the Rio Declaration (UN, 1992, principle 15) shall prevail, at least as long as significant uncertainty over environmental management remains.

This leads to the overall conclusion that deep-sea mining should, at least, be suspended until such time when we know enough to manage the risks to the environment.