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Mining the Bottom of the Ocean Is as Bad for the Environment as it Sounds

Marine biologists are warning of the threats the next frontier of mining poses to fragile ecosystems.
Image: Global Ocean Commission

Have you ever wondered how much the ocean floor is worth? The answer is in the trillions. Metals and materials are the foundation of our life, but with seven billion people occupying the earth, supplies are rapidly dwindling. So mining industries have set their sights miles deep under the sea. It's estimated there are billions of tonnes worth of valuable metals and minerals on the seabed.

However, marine biologists and researchers have raised concerns that those doing deep sea mining don't appreciate the delicate and fragile ecosystem of the deep-ocean, and how their actions could affect it.


Andrew Thurber, a researcher at the College of Earth, Ocean and Atmospheric Sciences at Oregon State University, talked to me about the issue. Thurber's review on the deep sea's relationship to us on land and our duty to protect it was recently published in Biogeosciences, a journal of the European Geosciences Union.

In their report, Thurber and his colleagues pointed out the many important uses of the deep sea. The deep sea is used as a dumping ground to absorb waste; it contains many life forms, some of which are being looked at for new medicines; and it serves as an environment for fish to breed. I asked Thurber about the implications of deep sea mining. "It's really not different from clear-cutting a forest of redwoods, except instead of majestic trees there are many small organisms that, together and en masse, gain their importance to the planet," he said. "We also know that many of the services that are provided by this habitat are connected."

Image: Nautilus Minerals

Thurber told me that if we alter the biodiversity of life under the ocean then we'll change the role of that habitat in the global carbon cycle. While that's not a big issue if we're talking about a few meters of seafloor, the extent of the area considered for mining is 90 percent the size of Australia. Fortunately, there are systems in place to monitor how big an area a corporation or country can "reserve" for mining.

The people responsible for issuing areas of the ocean for mining are the International Seabed Authority, or the ISA, which was established by the United Nations in 1982. They monitor anyone trying to mine under the ocean and are responsible for preserving areas of interest and making sure that damage is minimised.


The ISA produces maps showing the different countries and companies that have decided which part of the ocean "belongs to them." At the moment, nobody is allowed to mine the deep-ocean, but contracts have been issued which allow for prospecting and exploration of the seabed. Thurber told me that "much of the mining is in the final stages prior to its occurring—however, the machines that are aimed to do this are being built, which really changes things from 'might happen' to 'will happen soon.'" Nautilus Minerals, an industry leader in deep sea mining, have already come up with a plan of how their mining will be performed.

A map of sampling locations for polymetallic sulfides. Image: ISA

"The two most active areas of mining are polymetallic sulfides and manganese nodule fields," said Thurber. Polymetallic sulfides are mineral deposits containing three or more metals. Manganese nodules are rock concentrations, roughly the size of a potato, that contain iron, manganese, nickel, copper, and cobalt. Manganese is used to form many important alloys.

I asked Thurber if we'd be affected by deep sea mining on land. "The deep ocean is very closely linked to the function of the surface of the earth," he said. "It is the area where the nutrients that fuel the most productive fisheries on the planet come from and also acts as the major sink for carbon dioxide that we have released into the atmosphere." He added that, "Another aspect of this is the inherit biodiversity, which provides both excitement in exploration but also potential novel and powerful drugs. The deep sea is an active place where humans are searching out new cures for cancer with some potentially exciting leads."


Mining companies have tried to placate environmental worries by ensuring they'll do everything in a way that diminishes harm. But it's difficult to imagine how this will be done when their process involves dumping enormous mining machines on the ocean floor, which flatten it out and then scoop up large deposits of the earth. Nautilus Minerals has come up with a few different approaches.

For example, it told BBC Radio 4 that one of its plans before mining was to move the animals, mine, and move them back. I asked Thurber about this. "I like the idea but doubt the feasibility of it," he said. "Most animals are very delicate on the deep sea floor. Sea urchins have thin tests [the skeleton of a sea-urchin], especially at depth, and it is not common to have the most experienced submarine pilots and ROV [remotely operated underwater vehicle] pilots on the planet take minutes to hours to be able to move one into a collection device without damaging it. Nets and trawls destroy the delicate structures of feather stars, urchins, sea cucumbers, anemones and seastars. Corals are fixed to the hard substrate and would take a herculean effort to try and move a few feet, much less out of a mining claim." He said it was akin to removing all the deer from a forest, chopping it down, then putting them back.

It's easy to moan about how terrible the evil mining companies are, but they exist to meet our desires. "Deep sea mining is largely like most mining," Thurber said. "It is a destructive process that is used to get resources that are either wanted or needed. It's very easy to say it is 'bad' but I, like everyone, use materials that come from a mining operation and so rather than just say no, what is more important is to understand both the inherent risk to the ecosystem but also the other services that the ecosystem provides."

The deep sea has the resources to sustain our way of living for many years to come. When a land community is ruined by a mining company, we see the habitats destroyed and are able to smell the pollution that's emitted. But when these same things are happening miles beneath the ocean, it's easy to forget. Upsetting the delicate ecosystem between seabed and land could have grave effects for us in the future.

It's inevitable that deep sea mining will occur. What Thurber and his colleagues stress is most important is that measures are in place to protect the deep sea as best we can.