Bloomberg Law
Free Newsletter Sign Up
Bloomberg Law
Advanced Search Go
Free Newsletter Sign Up

Deep-Sea Mining for Rare-Earth Metals Looms, as Do Environmental Questions

Sept. 28, 2018, 10:01 AM

Once thought too expensive and too difficult, commercial scale mining of the deep sea is poised to become a reality as early as 2019. But scientists warn reaching rare minerals on and under the sea floor could cause irreversible damage to an environment that is still poorly understood.

As new technologies come online, mining companies are probing depths from 5,000 to 16,000 feet to expose new deposits of manganese, copper, cobalt, and other rare-earth minerals necessary to build everything from smartphones to solar panels to electric cars.

“People are making new discoveries almost every week; we’re nowhere near plateauing in our understanding of these deep-sea ecosystems,” said Lisa Levin, a biological oceanographer at the University of California-San Diego.

Given how little is known about deep-sea life, Levin told Bloomberg Environment that she feels mining should be delayed until regulators have a better grasp of biological consequences outside the mining footprint. “I just think we need to understand more about how these habitats interact, and how long they take to recover before we risk doing irreversible damage through mining.”

‘Plumes of Mud’

But compared to terrestrial mining, seafloor operations should have a smaller environmental footprint, potential ocean mining companies say.

“These include effectively no mine tailings, minimal pre-stripping of sediment, no vegetation stripping or water catchment issues, no permanent on-site infrastructure such as roads, power lines, or buildings " said Noreen Dillane, a spokeswoman for Nautilus Minerals Inc.

In Clarion-Clipperton Fracture Zone, a 1.7 million square mile deep-sea plain between Hawaii and Mexico, the U.S. Geological Survey estimates that there are about 21 billion metric tons of so-called “polymetallic nodules,” tennis-ball-sized chunks of ore high in manganese, nickel and copper, most of which are simply lying on the bottom of the Pacific.

Mining these nodules should have a “light touch,” according to Greg Stone, chief ocean scientist for DeepGreen, a seafloor mining startup based in Vancouver.

“A plume of fine sediment will be kicked up when a nodule is removed,” Stone told Bloomberg Environment. But the sediment resettles in a matter of days. Any creatures that live on the nodules will be killed, but overall the impacts aren’t expected to be significant, he said.

“We don’t have all the answers yet, but at least we’re not talking about mountains full of arsenic and toxic waste and blasting,” he said. “We’re talking about plumes of mud.”

Lasting Impacts

But scientists say even mining activity small in scope can create outsized impacts on habitat or marine life.

Emerging studies suggest that even small-scale sea-floor disturbances can affect habitats far outside the mining footprint, making it hard for slow-growing species of coral and fish to reproduce, especially in the areas around hydrothermal vents—a hotbed of biodiversity.

“These hydrothermal vents that are being targeted for mining are relatively rare, and often quite small,” said Cindy Van Dover, a professor of oceanography at Duke University in Beaufort, N.C. “I think we need more data to create effective baseline strategies that can be monitored for changes going forward.”

Complex Regulatory Challenge

On Sept. 17, United Nations negotiators met in New York to kick off a two-year process aimed at developing rules to protect the ocean from overexploitation.

The U.N. Convention on the Law of the Sea (UNCLOS) already includes a mandate to regulate mineral-related activities, but environmental groups claim those rules don’t go far enough.

“UNCLOS has a clear mandate to protect the marine environment from harmful effects. But in the case of mining we really don’t have a good understanding of what those measures are, or what constitutes harmful effects,” said Xiao Recio-Blanco, director of the Ocean Program at Environmental Law Institute, based in Washington.

Recio-Blanco said he has confidence in the International Seabed Authority, which oversees mining in international waters, but seafloor surveys are just now beginning to reflect the true abundance of life in areas marked for mining.

“It’s not that we want to close the entire sea off to mining,” he said, “but we need better science to translate that understanding into specific rules and thresholds for environmental impacts that would lead to a suspension of activities.”

The seabed authority is accepting comments on a draft plan for seabed mining until Sept. 30. Its goal is to release final rules by 2020.

U.S. Lagging Behind

To date, the authority has approved 29 exploration contracts in international waters.

However, since the U.S. Senate never ratified UNCLOS, American companies aren’t legally permitted to apply for prospecting contracts in international waters. But that doesn’t preclude U.S. companies from conducting mining operations inside the country’s 200 nautical mile exclusive economic zone.

“But that’s not really happening either,” said James Hein, a research geologist at the USGS’s Pacific Coastal and Marine Science Center in Santa Cruz, Calif.

“Congress has been passing all of these critical metals laws, but they’re not doing the things they should be doing to make progress in the marine environment,” Hein told Bloomberg Environment.

He blames Congress for failing to fund the deep-sea surveys necessary to locate mineral deposits.

“We can estimate what should exist in our own EEZ, the ridges around the Mariana Trench are thought to have the best ferro-manganese crusts the world. And companies from China, Korea, Russia, Japan have all taken out prospecting contracts just outside our EEZ,” he said.

To contact the reporter on this story: Adam Allington in Washington at; Stephen Lee in Washington at

To contact the editor responsible for this story: Rachael Daigle at