In a new report, the European Academies’ Science Advisory Council (EASAC) announced its support for a moratorium on deep-sea mining.

The report, which assesses evidence on future critical minerals needs, the potential for recycling and technology innovation, and the environmental impact of deep-sea mining finds that there is much uncertainty about the future balance of supply and demand.

The narrative for deep-sea mining often anticipates shortages in the metals required for the energy transition, with assertions that increased demand in ‘green technologies’ cannot be met from terrestrial sources. … The argument that deep-sea mining is essential to meet the demands for critical materials is thus contested and does not support the urgency with which exploitation of deep-sea minerals is being pursued. There remains much potential for policy to prioritise a circular economy, support innovation, and minimise continued dependence on the linear economy’s focus on extracting virgin materials from nature. The European Commission’s policy on critical raw materials and its regulation on recycling electric-vehicle batteries are welcome first steps and should lead to a framework that encourages recycling for all renewable energy systems.

—EASAC report

Location of the three main marine mineral deposits: polymetallic nodules (blue); polymetallic or seafloor massive sulfides (orange); and cobalt-rich ferromanganese crusts (yellow) (Miller et al. 2018).

The report notes that there are three main sources of deep-sea minerals: polymetallic or manganese nodules in abyssal plains, with much focus on the Clarion-Clipperton Zone in the Pacific Ocean; cobalt-rich ferromanganese crusts (CRCs) at the flanks of seamounts; and seafloor massive sulfides (SMS) deposits near active and inactive hydrothermal vents. Composition differs between these three, but the primary economic targets are manganese, cobalt, nickel, and copper for the first two sources, and copper, zinc, silver, and gold for SMS deposits.

A schematic showing the processes involved in deep-sea mining for the three main types of mineral deposit. Schematic not to scale. (Miller et al. 2018).

Although there are major knowledge gaps, the reports notes, on the basis of existing information it is clear that mining will have the following effects:

• Biota in the areas directly mined at the seabed will be killed.

• Sediment discarded on site is likely to be inhospitable to recovery for decades to centuries in the case of nodule mining, and decades for SMS mining.

• Loss in the structure of habitats may lead to indefinite reductions in biodiversity.

• The collateral ecological damage through sediment plumes will expand the area of impact at the seabed and in the water column.

• Noise, light, and vibration are other factors that may impact biota around the mining site.

EASAC is formed by the national science academies of the EU Member States to enable them to collaborate with each other in giving advice to European policy-makers. It thus provides a means for the collective voice of European science to be heard. EASAC was founded in 2001 at the Royal Swedish Academy of Sciences.

Resources

• Miller, K. et al. (2018). An overview of seabed mining including the current state of development, environmental impacts, and knowledge gaps. Frontiers in Marine Sciences 4, 418 doi: 10.3389/fmars.2017.00418