Mining on the ocean floor could do irreversible damage to deep sea ecosystems, according to a new study by researchers from the University of Exeter and Greenpeace.The deep sea (depths below 200m) covers about half of the Earth’s surface and is home to a vast range of species. Little is known about these environments, and the researchers say mining could have “long-lasting and unforeseen consequences”– not just at mining sites but also across much larger areas.
Rising demand for minerals and metals, including for use in new technology, has sparked renewed interest in seabed mining. Despite the term “mining,” much seabed mining would involve extraction of minerals over very wide areas of the sea floor rather than digging down to any great depth, potentially leaving a vast footprint on the deep-sea habitats in which these mineral deposits occur.
The study is the first to give a global overview of all current plans to mine the seabed, in both national and international waters, and looks at the potential impacts including physical destruction of seabed habitats, creation of large underwater plumes of sediment and the effects of chemical, noise and light pollution arising from mining operations.
“Our knowledge of these ecosystems is still limited, but we know they’re very sensitive,” said Dr. David Santillo, a marine biologist and senior Greenpeace scientist based at the University of Exeter.
“Recovery from man-made disturbance could take decades, centuries or even millennia, if these ecosystems recover at all. As we learn more about deep sea ecosystems and the role of oceans in mitigating climate change, it seems wise to take precautions to avoid damage that could have long-lasting and unforeseen consequences.”
Some operations are already taking place, generally at relatively shallow depths near national coastlines. The first commercial enterprise in deeper waters, expected to target mineral-rich sulphides at depths of around two kilometres (1.2 miles) off Papua New Guinea, is scheduled to begin early in 2019. Speaking about these plans last year, Sir David Attenborough said it was “tragic that humanity should just plough on with no regard for the consequences.”
The Exeter and Greenpeace research team say there are “many questions and uncertainties” around seabed mining, including legal issues and the difficulties of predicting the scale and extent of impacts in advance, and of monitoring and regulating mining activity once it takes place in the deep sea.
The paper says that alternatives to seabed mining have already been proposed, including substituting metals in short supply for more abundant minerals with similar properties, as well as more effective collection and recycling of components from disused products and wastes.
However, Santillo said demand for seabed mining would also diminish if humanity could cut over-production and over-consumption of consumer goods. “Rather than using human ingenuity to invent more and more consumer products that we don’t actually need, we could deploy it instead to build goods that last longer, are easier to repair and make better use of the limited natural resources we have,” he said. “With the right approaches, we can avoid the need for seabed mining altogether.”
More Concerns
Last year, the MIDAS project, which is made up of scientists, industry figures, NGOs and legal experts from 32 organisations across Europe, also warned on the potential for environmental damage in deep sea mining. They found that new environmental issues need to be considered, such as the large surface areas affected by nodule mining, the potential risk of submarine landslides through sediment destabilization in gas hydrate extraction or the release of toxic elements through oxidation of minerals during mining.
There is a risk that the mining process will release metal ions into the water column, either in the benthic plume created by mining vehicles or, following dewatering on the surface vessel, in a mid-water plume. Such plumes can potentially travel hundreds of kilometres, carrying potential toxicants with them. Mid-water plumes may impact photosynthetic microalgae or animals within the water column.
Currently the U.N. Convention on the Law of the Sea (UNCLOS) governs activity on the seabed. UNCLOS states that international waters are the “common heritage of mankind” and that the International Seabed Authority (ISA), based in Jamaica is the body responsible for administering it. The ISA has signed a number of mining deals.
SOURCE: MINING EXECUTIVE/PACNEWS
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