The price of seabed mining

Materials World magazine
1 Mar 2018

The first commercial deep sea mining project could begin in 2019. But, is enough being done to prevent harm to delicate seabed ecosystems? Khai Trung Le talks to Dr David Santillo about deep sea mining’s destructive potential.

Despite delays since 2008, Solwara 1, a deep sea mining project testing the potential of copper sulphides off the coast of Papua New Guinea conducted by Canadian underwater minerals exploration company, Nautilus Minerals, recently announced an expected 2019 start.

With deep sea mining slowly moving closer to realisation, a recently published paper from the University of Exeter, UK, asks whether enough has been done to mitigate harm to ocean ecosystems, or even whether we need to tap into the sea’s mineral-rich landscape.

The paper, An Overview of Seabed Mining Including the Current State of Development, Environmental Impacts, and Knowledge Gaps, published in Frontiers in Marine Science, explores the potential impacts including physical destruction of seabed habitats, large underwater plumes of sediment, and the impact of mining operations including increased temperature, chemical, noise, and light pollution.

Lead author, senior Greenpeace scientist and honorary research fellow at the University of Exeter, Dr David Santillo, told Materials World, ‘It will be impossible to avoid all damage to deep sea ecosystems. The process of mining involves the physical removal of habitat, the resuspension of sediments, and the discharge of wastewaters. If mining is to go ahead, governments and society will have to accept that it could involve damage over a wide area that will never recover in a human timescale.’

Santillo notes that ‘the risks we have identified are, at this stage, largely theoretical ones, though they are firmly based on scientific understanding that has built up over many decades’. Much of the uncertainty stems from the absence or scarcity of data. Among these repercussions, the creation of potentially toxic sediment plumes has been identified by researchers and by Nautilus Minerals itself. Created by seafloor production vehicles and processed material from surface support vessels, plumes may lead to significant physical alterations and potentially smother the benthic habitat. Nautilus revealed that the release of plumes from a sulphide test mining site resulted in sedimentation of up to 50cm within 1km of the discharge site, with some material dispersing up to 10km away. Natural sedimentation rates in these deep water areas are thought to be a few millimetres per 1,000 years.

Theory to ground

The most prominent seabed disturbance analysis comes from the Germany-led DISCOL and European MIDAS projects, which similarly concluded there was potential for toxic elements during the mining process, but accepted the difficulty in fully predicting the impact of release using laboratory experiments. However, Santillo adds, ‘Just as it is not possible to ensure accurate predictions of damage, so it is not possible to give confidence in advance that collateral damage can be avoided or minimised.’

Despite this, some, including Jens Greinert, head of the deep sea monitoring research unit at the GEOMAR Helmholtz Centre for Ocean Research, Germany, believe heightened environmental consideration puts seabed mining on the right foot. Greinert said, ‘On land, with oil and gas, nobody asked [about potential environmental damage] before. All the regulation was established after the damage was made. Now we’re doing it jointly together before something happens.’

As there are no current seabed mining activities, Santillo said regulations are likely to be agreed upon beforehand but was unconvinced of their efficacy. ‘It is one thing to have regulations in place, but quite another to ensure that those can be properly furnished with data, are open to independent scrutiny, and effective in preventing or mitigating damage.’ He points to the difficulty in ensuring accountability at extreme depths, and the uncertainty of where responsibility would lie. ‘We highlight in our paper that the deep seabed is a very sensitive environment. If damage from a particular activity does prove to be more impactful than anticipated, would it be possible to take any meaningful actions to rectify it?’

Salvage rights

The International Seabed Authority (ISA) has regulatory responsibility for activities and resources on and in the seabed – referred to as the mining code – but only in places beyond the limits of national jurisdiction. Regulations within national jurisdiction are expected to be arranged between national governments and deep sea mining companies, with Solwara 1 a potential primer for future agreements.

Other countries interested in deep sea mining include Mexico, New Zealand, Norway (see Materials World, December 2016) and Chile, one of the most active members of the ISA Council. But Nautilus’ project continues to be the most immediate hope to show the potential of seabed mining, despite almost a decade of delays. There remain uncertainties, but Santillo believes this is the closest Solwara 1 has come to implementation. ‘The entire project could still come to a halt and be cancelled before it begins, depending on Nautilus’ standing in Papua New Guinea, the company’s commitment and performance, and whether there continues to be effective opposition. But if it does eventually go ahead, it will be a watershed moment, and a point of no return.’

The paper, An Overview of Seabed Mining Including the Current State of Development, Environmental Impacts, and Knowledge Gaps can be read at