Japan prepares to mine its deep seabed by decade’s end

TOKYO — Japan is actively exploring pathways to mine the deep sea of its exclusive economic zone (EEZ), in an effort to lessen reliance on imported mineral resources needed for advanced and green technologies.

Aiming to be ready to mine by the late 2020s, Japan — one among just a handful of nations actively pursuing deep-sea mining within their own waters — could be among the first nations to exploit the deep sea. The country has completed multiple small-scale mining tests that it claims are world firsts, and it positions itself as a global leader in the “sustainable development” of deep-sea mining.

Critics warn that mining could harm deep-sea ecosystems, including by directly destroying habitat and by releasing plumes of fine particles that currents carry away to smother neighboring habitats. More than 20 countries have called for either a ban, moratorium or precautionary pause on deep-sea mining, and more than 800 marine scientists and other experts have signed a statement calling for a pause. Well aware of such concerns, the Japanese government is gathering data on deep-sea ecosystems and developing technologies to monitor and minimize mining’s environmental impacts. Its small-scale tests to date have shown lingering impacts to fauna in and near the test sites.

“We should only be mining if we can establish a robust system that properly takes environmental impacts into account,” Yoshihito Doi, a member of the Agency for Natural Resources and Energy, part of the Ministry of Economy, Trade and Industry (METI), told Mongabay. At the same time, he said, “We believe it’s important, from the perspective of economic security, to have a system in place that enables us to access [deep-sea minerals].”

The island nation is exploring three types of deep-sea mineral deposits in its EEZ: polymetallic sulfides at inactive hydrothermal vents, cobalt-rich crusts on seamounts and rare-earth mud on the deep-sea floor. It also has contracts with the International Seabed Authority (ISA), a U.N.-affiliated body headquartered in Jamaica, to explore for polymetallic nodules and cobalt-rich crusts in international waters.

The government, rather than private companies, is leading Japan’s mining plans. Key actors include the Cabinet Office, METI, the Japan Organization for Metals and Energy Security (JOGMEC) and the Japan Agency for Marine-Earth Science and Technology (JAMSTEC).

The government began seriously considering deep-sea mining in Japanese waters more than 15 years ago, with a 2007 law on ocean policy promoting the development of seafloor mineral resources. The Cabinet Office has sponsored a mining project since 2014 as part of its Strategic Innovation Promotion Program (SIP), and its 2023 fourth basic plan on ocean policy laments Japan’s “reliance on certain countries” for rare-earth and rare-metal processing — China dominates, with roughly 70% of global rare-earth production — and stresses the importance of Japan commercializing its deep-sea resources.

Polymetallic sulfides at hydrothermal vents

In January and late summer 2017, JOGMEC performed the world’s first test excavations of polymetallic sulfides containing zinc, lead, copper, gold and silver from an inactive hydrothermal vent roughly 1,600 meters (5,249 feet) deep in the Okinawa Trough, southwest of Japan’s main islands.

JOGMEC, which declined Mongabay’s request to interview an official through a spokesperson, has been exploring hydrothermal deposits in Japan’s EEZ since 2008, including in the Izu and Ogasawara island chains.

Active hydrothermal vents are oases of life in the deep sea, filled with organisms uniquely adapted to surviving in the chemical-rich waters. Although inactive vents don’t sustain as much biomass, experts worry that mining could harm both active and inactive vent ecosystems.

JOGMEC’s January 2017 excavation, which it called a “disturbance test,” removed roughly 20 cubic meters (706 cubic feet) of minerals and sediment over six hours. A 2023 analysis of environmental data collected up to 55m (180 feet) from the test site noted “possible impacts” to nematode and macrofauna communities even three years after the test, although findings were “unfortunately limited by the low numbers of sampling sites and times.”

Full-scale mining of sulfide deposits would likely cause greater environmental impacts than the small-scale tests, according to a 2023 JOGMEC report. It would entail digging up to 30m (98ft) into the seafloor. And it would likely target a given location for months or years, Travis Washburn, a benthic ecologist who helped analyze JOGMEC’s data when he worked for the Geological Survey of Japan, told Mongabay.

In his view, larger-scale testing is necessary to better predict commercial mining’s environmental impact. “You can’t really understand what’s going to happen until you do it,” he said.

Inactive vents are often located near active ones; the 2017 disturbance test, for example, occurred roughly 200m (656ft) from an active vent. Although many unknowns remain about how far plumes will travel during commercial mining, “Depending on the proximity, it is likely that active vents will be impacted by plumes from mining at nearby inactive sulfides,” Washburn wrote in a subsequent email.

The disturbance test analysis also notes that the release of toxic metal particles potentially lethal to exposed organisms is among the greatest risks from sulfide mining, and other research shows this is the riskiest mining method in that regard. The 2023 JOGMEC report states that released toxic particles would “impact” marine ecosystems, and that it is “difficult” to remove them from mine waste with equipment.

JOGMEC’s report also states that going forward, the organization will “consider how best to monitor environmental impacts from commercial-scale mining.” It also aims to “set the scope of conservation [areas] to protect biodiversity” from mining, a measure recommended by the Convention on Biological Diversity and the deep-sea scientific community.

To help formulate such conservation strategies, Japanese researchers have been surveying vent ecosystems in the country’s EEZ for more than a decade. A 2014 JAMSTEC survey identified vent sites with unique local populations that “should be conserved” from mining and other human activities to avoid extinction. In 2016, JAMSTEC researchers and others mapped larvae dispersal between vent fields in the western Pacific Ocean, and in 2018 JAMSTEC used such data to model vent communities’ ability to recover from disturbance.

The Cabinet Office’s plan on ocean policy aims to “start working toward commercialization” of sulfide mining by the late 2020s.

Cobalt-rich crust on seamounts

JOGMEC performed another world-first mining test in 2020, excavating 649 kilograms (1,430 pounds) of cobalt- and nickel-rich crust from a seamount near Minami-torishima, a 1.5-km2 (0.58-mi2) island located nearly 2,000 km (1,240 mi) southeast of Tokyo.

Seamounts are hotspots of biodiversity, providing exposed rock for corals and sponges to grow as well as upwellings of nutrient-rich water that support abundant plankton and ensuing food chains.

A JOGMEC news release stated that environmental monitoring of the 2020 test aimed to “rule out any serious environmental impact.” However, experts, including Washburn, who analyzed the data found decreased densities of mobile seafloor-dwelling animals and swimmers compared with before the test in the area impacted by the excavation and its plume, which extended a “few hundred meters” from the mining site. A year after the test, these animals’ numbers were still down by roughly half.

“Even a very small-scale seamount excavation may substantially alter benthic communities,” the authors wrote.

Currently, Japan has no timeline for commercial mining of cobalt-rich crust, Doi said.

This may be just as well. Although cobalt is currently sought for battery production, Matthew Gianni, a co-founder of the Deep Sea Conservation Coalition, a network of NGOs that opposes deep-sea mining, told Mongabay that battery technology is shifting away from high-cost metals such as cobalt and nickel. If Japan were to begin mining based on today’s battery market, “it may be end up mining stranded assets,” he said.

Rare-earth mud on the deep-sea floor

In 2011, University of Tokyo researchers reported the discovery of deep-sea mud in the Pacific containing high concentrations of rare-earth elements and yttrium, a mixture known as REY. Further surveys confirmed such mud inside Japan’s EEZ, at a depth of 6,000 m (19,685 ft) around the base of seamounts near Minami-torishima.

By 2027, the Cabinet Office’s SIP project aims to demonstrate technology able to pump 350 metric tons of rare-earth mud up from the seafloor and process it per day. In 2022, JAMSTEC announced it had conducted a successful test of the mining technology.

The press release noted that the test also confirmed the utility of a high-tech environmental monitoring system being developed through the SIP project. Able to collect data from the seafloor, midwater and surface, the system can transmit information to the mining vessel about potential problems such as leaks. “We can quickly respond and stop operations if that kind of major risk occurs,” Hiroyuki Yamamoto, a JAMSTEC benthic ecologist involved in the SIP project, told Mongabay.

Like any kind of deep-sea mining, extracting rare-earth mud will likely create a plume. SIP project engineers are working to minimize it by mining within a closed chamber, Yamamoto said. In his view, mining rare-earth mud would have less overall environmental impact than mining sulfide deposits because the mud is easier to extract and contains only background levels of toxic elements.

Balancing the environment and the economy

Many challenges remain before full-scale mining in Japan’s EEZ can begin, Doi said. In addition to overcoming technological hurdles and setting the scope of environmental monitoring, “We need to investigate further whether there really are enough mineral resources to make [mining] economically beneficial,” he said.

Japan plans to follow international rules set by the ISA even when mining in its EEZ, according to Doi. Currently, the ISA has guidelines for deep-sea mining exploration; regulations for exploitation — commercial mining — are still in draft form and under discussion.

Acknowledging that environmental impacts “won’t be zero,” Doi highlighted Japan’s initiatives to minimize them, including tracking plumes from mining tests and researching deep-sea animal population networks.

Such research is a positive sign, Shigeru Tanaka, deputy director general of the nonprofit Pacific Asia Resource Center, which advocates for a moratorium or ban on deep-sea mining, told Mongabay. “They’re doing this research, of course, for the development of minerals, but at least they have some idea of what’s bad and what’s worst,” he said.

Still, Tanaka warned that with various government organizations from the Cabinet Office down pushing forward with mining, the process lacks a break mechanism. When it comes to deep-sea mining, support for regulations has come to signify support for mining, and the Japanese government may view environmental research and protection as a prerequisite for mining to begin, rather than a potential reason to stop, he fears.

Banner image: Deep-sea mining equipment aboard the D/V Chikyu. Image courtesy of JAMSTEC.

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Citations:

Okamoto, N., Shiokawa, S., Yamaji, N., Sakurai, H., & Kurihara, M. (2019, June). World’s First Lifting Test for Seafloor Massive Sulphides in the Okinawa Trough in the EEZ of Japan. Paper presented at 29th International Ocean and Polar Engineering Conference, Honolulu, HI. https://publications.isope.org/proceedings/ISOPE/ISOPE%202019/data/69366-isope-v1-1.4532365/t001-1.4534276/f001-1.4534343/a001-1.4534344.html

Van Dover, C., Arnaud-Haond, S., Gianni, M., Helmreich, S., Huber, J., Jaeckel, A., … Yamamoto, H. (2018). Scientific rationale and international obligations for protection of active hydrothermal vent ecosystems from deep-sea mining. Marine Policy, 90, 20-28. doi:10.1016/j.marpol.2018.01.020

Washburn, T., Iguchi, A., Yamaoka, K., Nagao, M., Onishi, Y., Fukuhara, T., … Suzuki, A. (2023). Impacts of the first deep-sea seafloor massive sulfide mining excavation tests on benthic communities. Marine Ecology Progress Series, 712, 1-19. doi:10.3354/meps14287

Van Dover, C., Colaço, A., Collins, P., Croot, P., Metaxas, A., Murton, B., … Vermilye, J. (2020). Research is needed to inform environmental management of hydrothermally inactive and extinct polymetallic sulfide (PMS) deposits. Marine Policy, 121, 104183. doi:10.1016/j.marpol.2020.104183

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