A section of a 1000m deep seamount south of Tasmania, showing a brittlestar and sea urchins. Deep sea ecosystems are at particular risk from the impacts of deep sea mining. Photo Credit: NOAA Photo Library, Public domain, via Wikimedia Commons
As the world looks towards new technologies in an attempt to transition to cleaner, more sustainable energy sources, demand for raw materials such as lithium, nickel and manganese used in electronics will rise. The sourcing of these materials will be vital in the future economy and one technique that has been proposed to obtain them is deep sea mining (DSM). DSM means harvesting potato-sized mineral deposits known as polymetallic nodules from the floor of the deep ocean.
These nodules provide a rich source of metals such as lithium, cobalt and nickel needed for new technologies, but their exploitation has been the source of much controversy. In March, Fauna and Flora International (FFI), a wildlife conservation organization, published a report outlining the impacts and risks of DSM. Outlining the potential impacts on areas including carbon cycling, ocean biodiversity and human society, it ultimately called for DSM to be avoided entirely until more is known about the potential hazards.
“Many countries, companies and organisations believe not enough is known about the deep sea for it to go ahead”
Governance of the deep sea, below the depth of around 200m and beyond continental shelf, is fragmented due to its location outside of national borders. The UN’s International Seabed Authority (ISA) regulates the use of the deep sea under the UN Law of the Sea which stipulates that the seabed must be managed for the benefit of all mankind. The ISA have already granted 18 DSM exploration permits for the Clarion-Clipperton Fracture Zone (CCZ), a deep sea plain between Hawaii and Mexico, that can begin being used this year. These permits are highly controversial as many countries, companies and organisations believe that there is not enough known about the deep sea and the potential impacts of deep sea mining for it to go ahead.
In 2021, members of the International Union for Conservation of Nature (IUCN) voted to support a moratorium on deep sea mining until further research has been completed. However, the government of Nauru, a Pacific island state, activated a subclause in the UN convention on the Law of the Sea which allows countries to pull a two-year trigger if they feel negotiations are going too slow. Nauru Ocean Resources Inc. (NORI) had plans to begin mining in the CCZ in 2023, and needed regulations to be in place by then. They have therefore given the ISA until June this year to finalise regulations on DSM—otherwise mining contractors will be allowed to start regardless. FFI’s recent report calls for a longer-term ban from the ISA on DSM activity and highlights the need for more research in this field.
The major issue brought up in the report is how little we know about the deep ocean itself. Humanity is still in the discovery phase when it comes to the ocean, with more than 75% of the sea floor remaining unmapped or unobserved. Less than 1% of the deep ocean has been explored due to the intense pressure from the water column equipment would need to be able to withstand. The likelihood of causing damage to ecosystems and species that we have not yet discovered is high. The ocean itself plays a major role in the functioning of our planet in terms of carbon cycling, climate regulation and ecosystem productivity so any impacts have the potential to spread beyond just the seas.
The polymetallic nodules targeted by DSM operations are crucial for ecosystems themselves, providing unique habitats for organisms that play a key component in deep sea food chains. Deep sea ecosystems are not very resilient, as they are adapted only to a narrow range of physical and chemical conditions. Any deviation from these could cause long lasting effects that various species may struggle to recover from. As these ecosystems are already being disrupted by climate change, amongst other stressors, their resilience to the impacts of DSM will be especially low.
The role that deep sea species play in global nutrient and resource cycling is not yet well known so the long-term impacts that these ecosystems may suffer is virtually impossible to predict. The ocean is known to store over 90% of excess heat from global warming with marine sediments being one of the planet’s most crucial carbon reservoirs. DSM may alter the long-term carbon cycle significantly, releasing carbon that would have otherwise been sequestered. As a consequence, the rate of atmospheric carbon accumulation is perhaps accelerating.
“Deep sea mining may alter the long-term carbon cycle significantly”
The main disruptor to deep sea ecosystems would be the sediment plumes created when collector vehicles are dragged across the sea floor. The deep sea is a typically clear environment without any sediment clouding the waters. Waters are very still, lacking any currents to wash away sediment plumes. The sand and other debris in plumes may smother vulnerable organisms like sponges and corals; it can block their respiratory systems and may impact other vital behaviours, such as visual communication and bioluminescent signaling. This might interfere with organisms’ ability to catch prey or reproduce. Affecting even a single species can cause a much larger disruption to the deep sea ecosystem, due to the interdependence of species living in this habitat.
FFI’s report went on to analyse potential mitigation techniques, but concluded that full mitigation and prevention of long term impacts is not possible until further research into the deep ocean has been done. There remains scope for future technological innovations to make deep sea mining a safer reality—but, they conclude, at the current stage of research, the impacts cannot be effectively avoided or managed.