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May 7, 20236 min read

Deep Sea Mining: Will it do more harm than good?

One of the biggest challenges facing today’s society is the transition to a low carbon economy. Technologies such as electric cars, solar panels and wind turbines are becoming more and more popular as we shift away from fossil fuels but the growing demand for them is resulting in a growing demand for the raw materials needed for their manufacture. The World Bank has predicted a 50% increase in the demand for cobalt by 2050 along with a rise in the demand for other metals such as nickel and manganese.


Deep sea mining (DSM) has been proposed as a solution to obtaining these metals but the solution itself has triggered widespread debate in the political and scientific community over the potential threats it may pose to the deep sea and wider ocean environment.


Photo of some polymetallic nodules on the deep sea floor. Taken from NOAA https://oceanexplorer.noaa.gov/okeanos/explorations/ex1907/logs/nov7/nov7.html



What is Deep sea mining?


DSM involves the extraction of raw materials from the deep sea. The biggest resource that is currently being explored is polymetallic nodules that are potato sized mineral deposits scattered on the seafloor. The nodules are thought to have grown over millions of years by metal ions from the seawater precipitating around an object such as a clam shell that has fallen to the seafloor. The nodules have an incredibly slow growth rate of about one centimetre every million years so although the resource may currently look abundant, it is by no means renewable.


There has been talk of mining/extracting these nodules since the 1970s but only in recent years have we developed the technologies to make it financially feasible. This being said, the process cannot yet be considered environmentally sustainable hence the ongoing debates surrounding DSM policy.


What is the current policy?


Governing the ocean is tricky territory when regarding deep sea areas outside of national jurisdiction (the control of a given country). The UN Law of the Seas says that the high seas and seabed are ‘common heritage of mankind’ and so they need to be governed to benefit of everyone. The International Seabed Authority (ISA) which is under the UN is responsible for regulating the seabed so set the rules and regulations that companies/countries have to follow when it comes to DSM. They have already granted 18 exploration licenses and are working towards setting regulations for commercial DSM.


However, in June 2021 the state of Nauru (a Pacific island nation) activated a subclass in the UN Law of the Sea where they can give the ISA a two year time frame to make decisions if they feel negotiations are going too slow. This gives the ISA until June 2023 to come up with their regulations regarding DSM or the mining contractors can start work regardless.


Since then, the International Union for the Conservation of Nature (ICUN) have called for a moratorium (a legal temporary ban) on DSM activities until a number of requirements are met such as fully understanding the risks. This has been supported by a number of countries as well as companies such as Google, BMW and Samsung.


In 2020, Fauna and Flora International (a wildlife conservation organisation) published published 'An assessment of the risks and impacts of seabed mining on marine ecosystems’. This report highlighted the potential risks involved in DSM. The release of the licenses by the ISA and the actions of Nauru along with a rapid increase in research and technological development in the area of DSM have caused Fauna and Flora to release an updated report in March 2023. The conclusion remained much the same, it is too early for DSM to go ahead as we do not yet have enough knowledge of the deep sea environment to safely assess potential issues and successfully bring about mitigation strategies.



What are the issues?


DSM could bring plenty of economic opportunity to nations such as Nauru especially where land mining is not possible but many scientists argue that the risks, especially the unknown risks, greatly outweigh any potential rewards. There are many potential issues surrounding DSM, some of which are summarized below.


The main issues which was heavily highlighted in Fauna and Flora’s recent report was the lack of information and knowledge we currently have about the deep ocean. Over 75% of the seafloor is currently unmapped and undescribed with humans having explored only around 1% of the deep ocean. We are very much still in the discovery phase when it comes to the deep sea and DSM could lead to impacts on species and ecosystems we are still yet to discover. Putting policy in place to protect something we know nothing about is an impossible task and with the ocean playing a key role in carbon cycling and basic functioning of the planet, any unforeseen issues could have a devastating impact.


Under the UN Law of the Sea, the ISA have an obligation to protect the seabed and prevent it from serious harm and this cannot be done until an accurate baseline data set has been established for a variety of deep sea environments. A task that although more and more studies are being published on, is not anywhere near being complete.


The extraction of polymetallic nodules from the seabed could cause major disruption to fragile ecosystems which could take extremely long timescales to recover, if they manage to recover at all. The nodules themselves can provide unique habitats fro a range of species, therefore making them vital to the ocean food web. These deep sea species are used to the very stable environment that the seafloor provides them with, the resilience of these species to any disruption is likely to be very low as species have evolved to fit the specific, narrow range of conditions found in the deep sea. Disruption to these delicate ecosystems could cause extinction of species that we don’t even know exist yet, not to mention ones that are vital in the storage and cycling of carbon.


Carbon cycling and storage is a critical process when it comes to the Earth’s regulation, a process that humans have already began to irreversibly disrupt through the release of carbon emissions. The ocean, especially the deep ocean, plays a critical role when it comes to the carbon cycle so it is worried that DSM could have major effects on the global climate. Marine sediments store a lot of carbon and over 75% of this is stored in sediments of the abyss (deep ocean). The breakdown of even a tiny bit of these sediments could release carbon and add to the greenhouse effect, ultimately enhancing the climate crisis.


Global warming however will not be the only consequence of DSM felt by humans. Whilst the deep sea may seem like a very far away place, the ocean is an extremely integrated system and communities that rely on fishing and marine ecosystems will feel a great impact. Not only is the decline of fish stocks due to disruption of the food chain a risk but also the risk of accumulation of toxic metals ingested lower down the food chain that could contaminate fish stocks and be consumed by humans. This is known as bioaccumulation. The magnitude of human health risk is not currently known but threats to the fundamental human rights of health and a clean, healthy and sustainable enviornement could be affected.



How do these issues come about?


The technology needed for DSM is substantially different to that used for mining on land. Pressure on the seafloor can be up to 500 times greater than at the surface. A variety of machinery is being tested but the current suggestion of a combine harvester type machine with a surface vessel poses the issue of sediment plumes.


The collector vehicles will disrupt the sediments on the seafloor, kicking them up into plumes which will then hang around due to the lack of ocean currents at depth meaning nothing is around to disperse them. The deep sea is an environment where the water is typically very clear so organisms wont be used to having sediment plumes around them. Organsisms may be smothered or communication mechanisms such as bioluminescence may be inhibited. This could affect predation and reproduction, potentially wiping out species all together. These plumes may also be recreated in surface or midwaters due to discharge from the surface vessels when any extra sediment is brought up with the nodules. The midwaters are constantly in motion and mixing with each other so these impacts are harder to predict. To further this, the acoustic energy generated by DSM could extend for hundreds of kilometers and impact marine mammals and other species in the surrounding areas. Without sunlight reaching deep sea beds, many organisms rely on noise and vibration which makes any artificial acoustic energy particularly disruptive.



How can they be prevented?


Fauna and Flora’s report was calling for DSM to be prevented until impacts are better known so that successful mitigation techniques can be put in place. Preventing impacts is the only way that both short and longterm harm can be prevented. There are certain ways that impacts can be minimised such as leaving certain mineral nodules alone or developing new technologies that will hover above the seafloor. But these will be region specific and are yet to be properly tested or assessed. This being said, the possibility of innovations remains out there for the future.



So is DSM a good idea?


Ultimately, Fauna and Flora’s report concludes that it is too early for DSM to occur and will remain so until suitable mitigation techniques have been developed and are well understood. The reasons discussed above are evidence that there are many negative impacts associated with the idea which need to be weighed up against the positives.





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