The long-term ecological impacts of seabed mining on marine environments are still largely unknown and have the potential to cause irreversible damage. Deep-sea mining – extracting naturally occurring rock deposits of cobalt, manganese and other minerals at depths below 200 m – is particularly risky, considering just one-fifth of the global ocean floor has been mapped by scientists and there is limited data for nearly 80% of the Earth’s oceans. California’s state-level legislation will ensure the protection of marine habitats and safeguard coastal areas and industries such as tourism and fishing.

Following the move and together with Oregon and Washington’s existing legislation, over 7,700 square miles of US ocean will now be protected against seabed mining activities. Marine species such as the endangered coho salmon, which hatch in freshwater streams that migrate into ocean waters along the US west coast, could be particularly susceptible to disturbance from seabed mining.

California’s state waters do not contain rich deposits of battery metals commonly targeted in seabed mining operations. However, waters along the state’s south coast could see increased future interest in extracting gold, titanium, and precious and semi-precious metal deposits. Meanwhile, interest could grow toward mining for phosphorites – a component used in industrial fertiliser – in waters around Southern California.

Disturbances caused by industrial seabed mining operations can threaten delicate marine ecosystems along the seabed, including up to two-thirds of all mollusc species found in the deep ocean. Such operations could also generate excessive light and noise pollution – with the latter having the potential to stretch across 500 km of ocean and create a “cylinder of sound” from the seabed to the ocean surface. This has the potential to influence the behaviour of marine mammals, such as whales, narwhals and dolphins, which rely heavily on sound.

Interest in deep-sea mining activities is rapidly gaining interest, mostly driven by the need to decarbonise, electrify and scale up low-carbon technologies such as wind turbines and electric vehicle batteries. Therefore, some view deep-sea mining as the best solution to secure metals, which in some areas are abundantly found along the seabed. However, there are too many significant gaps in understanding the ecological impacts of seabed mining to allow exploration at present, a recent study concluded.

Others believe that the arguments promoting deep-sea mining are flawed and that deep-sea exploration is not needed for the low-carbon transition. According to researchers, future demand predictions do not consider alternative solutions that can lower the demand for mineral resources. For instance, a combination of developing innovative alternatives, improving metal recycling and repairs could mitigate industrial needs for raw materials.

Elsewhere, action is being taken to protect seabed habitats. Environmental groups are calling for a global moratorium on deep-sea mining until its impacts are better understood. The G7 countries have also agreed that strict environmental controls should be implemented for seabed mining activities.

On a country level, Palau, Fiji and Samoa formed the Alliance of Countries for a Moratorium on Deep-sea Mining in June this year and are the first countries to oppose deep-sea mining in international waters. The Pacific nations are located near the Clarion Clipperton Zone, a stretch of ocean that contains over 20 million tonnes of minerals and which is likely to see pressure for large-scale industrial resource extraction begin. Last year, New Zealand’s supreme court upheld the decision of a lower court to reject a deep-sea mining project on environmental grounds.

Source: PEW