Global demand for raw materials has risen sharply in recent decades. To meet the need for valuable metals like nickel, copper, and cobalt, deep-sea mining is increasingly being discussed as an option. This type of mining targets deposits in the deep sea, particularly manganese nodules, massive sulphides, and iron-manganese crusts, which contain valuable metals. While some view these resources as essential for modern technologies, critics warn of the yet-unknown ecological consequences.
The role of the International Seabed Authority (ISA)
A large portion of deep-sea deposits lies beyond national boundaries and is regulated by the International Seabed Authority (ISA). The ISA grants exploration licences and develops mining regulations, known as the “Mining Code”. Negotiations on the framework for future deep-sea mining have been ongoing since 2016. Despite progress, industrial extraction is not yet permitted, and the ecological impacts remain largely unstudied.
Manganese nodules: Focus on the Clarion-Clipperton Zone
The Clarion-Clipperton Zone in the Pacific, an area larger than the EU, contains vast manganese nodule deposits. Estimates suggest that 25 to 40 billion tonnes of these nodules, rich in nickel, copper, and cobalt, could be found here. However, only around 15 to 25 per cent of the area is actually suitable for commercial extraction.
The deep sea – a fragile ecosystem
The deep sea is the largest and least explored habitat on Earth. The organisms living there are adapted to extreme conditions and are highly sensitive to disturbances. The sediment layer on the ocean floor plays a central role in the nutrient cycle and harbours a variety of species that are still unknown. Extracting these layers would irreversibly destroy these habitats. Since deep-sea organisms grow very slowly and often have long lifespans, the damage would be permanent.
Consequences of deep-sea mining
The extraction of raw materials from the deep sea would disturb the upper, biologically active layers of the seabed. Large sediment plumes could spread over vast areas, potentially smothering sessile organisms such as corals and sponges. The disruption of this fragile ecosystem could also interfere with the deep-sea nutrient cycle and the associated water layers.
Another risk factor is the discharge of process water contaminated by the mining process, which could harm marine life. Additionally, noise pollution from vehicles and ships presents a problem, as sound travels widely in the deep sea. Although floodlights used to illuminate the deep sea are often replaced by hydroacoustic techniques, the long-term impacts on the marine environment remain uncertain.
An intervention with long-lasting consequences
Long-term studies show that the ecosystems in manganese nodule fields cannot recover from disturbances within human timescales. The destruction of ecosystems and disruption of nutrient cycles may last for thousands of years. Therefore, the decision on whether and how deep-sea mining should proceed requires careful consideration and further research to avoid irreversible damage.
