Since the influential book Mineral Resources of the Sea by J. L. Mero was published a half-century ago, governments and mining companies have dreamed of extracting untapped metal and mineral deposits from the sea floor.
Progress has been stuttering, but the technology is now sufficiently advanced that commercial scale deep sea mining is considered by many observers to be imminent.
A decade ago, deep sea mining exploration centred around prospects off Papua New Guinea, and the target was massive sulphide deposits rich in copper, gold, silver, and zinc, occurring around active or dormant hydrothermal vents. Now, geopolitical and economic forces have shifted attention to the Clarion-Clipperton Zone, a 4.5 million square kilometre swath of Pacific seafloor stretching between Hawaii and Mexico. This time the focus is on mining polymetallic nodules: billions of mineral-rich, potato-sized rocks littering the seafloor at depths of 3000 to 6000 meters.
“There’s a bunch of very valuable metals in polymetallic nodules,” says Andrew Thaler, CEO of the environmental consulting firm Blackbeard Biologic and adjunct professor at the Universities of Maryland and Delaware. “But the real driver of the industry is cobalt. We need cobalt in batteries and we need cobalt in smartphones.”
Last year, the International Energy Agency’s Global EV Outlook cautioned that skyrocketing demand for cobalt in electric vehicle batteries could lead to critical shortages of the element.
Polymetallic nodules are found on the abyssal plains – vast seafloor mudflats covering over half the earth’s surface – which, despite their bleak moniker and homogeneous appearance, support a phenomenal amount of life.
“I think it’s fair to say that the biodiversity, just on species count, rivals the tropical rainforest,” says Thaler.
The denizens of the abyssal plains are modest: worms, crustaceans, mollusks and microorganisms. Lacking the “big, sexy” appeal of ecosystems surrounding hydrothermal vents, Thaler says the plains are largely ignored in scientific literature.
“We’re not going to close any cobalt mines when we start mining the high seas.”
This knowledge gap means the biggest risk of mining polymetallic nodules is that almost nothing is known about the abyssal plains ecosystem. “Even doing a really basic risk assessment is tricky,” Thaler says.
Though it’s still theory, polymetallic nodules would be mined using remote-controlled machines resembling underwater bulldozers, each equipped with a vacuum-shovel attachment to suck nodules off the seafloor.
“These ecosystems take tens of millions of years to form, and so essentially, if you’re disturbing the seafloor under a nodule field, that’s gone for the rest of human history,” Thaler says.
The ore would be pumped up to a ship and processed, with waste tailings returned to the ocean floor – creating a sediment plume that could bury and smother organisms. As well, disturbing seafloor sediments could release unknown amounts of stored carbon, potentially making climate change worse.
According to a July Greenpeace report, In Deep Water, the combined risks pose “severe and potentially irreversible environmental harm, both at the mine site and beyond. The deep ocean’s biodiversity and ecosystem functioning is barely understood and robust mitigation is not possible.”
The Deep Sea Conservation Coalition, a group of over 80 non-governmental organizations, advocates extreme caution. Mining should not be permitted, they argue, without a strong regulatory framework and until sufficient scientific information is available to ensure effective conservation management plans can be put into place, including a network of marine protected areas and reserves.
“The question isn’t ‘can it be done and not disturb the environment?’ but rather, ‘is the ecosystem big enough that some extraction isn’t going to impact the overall health of the ecosystem?’ With the assumption that any extraction is going to be catastrophic to the local environment.”
The Greenpeace report also accuses the International Seabed Authority (ISA), the intergovernmental body tasked by the UN with regulating deep sea mining, of placing mining interests over marine protection.
The ISA denies the claim, but must balance a dual mandate to concurrently protect seafloor ecosystems and commercialize the seafloor.
“Even the ISA reps will acknowledge it’s a contradictory mandate they have to work within,” Thaler says. But because the ISA was formed under the United Nations Convention on the Law of the Sea, and its directives can’t be altered without altering that Convention, the ISA is “stuck with the management regime they’ve been dealt,” he says.
The ISA unveiled draft regulations for seafloor exploitation this summer that will be debated and finalized over the next several years.
Mining active hydrothermal vents should be off limits, says Thaler, with no way to mitigate risk to ecosystems. For polymetallic nodules, he says it’s a matter of scale: “The question isn’t ‘can it be done and not disturb the environment?’ but rather, ‘is the ecosystem big enough that some extraction isn’t going to impact the overall health of the ecosystem?’ With the assumption that any extraction is going to be catastrophic to the local environment.”
And while mining polymetallic nodules is widely seen as less damaging than land-based cobalt mining in places such as the Congo, “We’re not going to close any cobalt mines when we start mining the high seas,” Thaler says.
While the ISA controls regulations, the vagaries of commodities markets, extreme technical challenges, and social license ultimately dictate the future of deep sea mining.
Canadian mining company Nautilus Minerals learned this the hard way. With well-explored claims off the coast of Papua New Guinea, a decade ago they were predicted to be the world’s first commercial deep sea mining operation around this year. Nautilus is now insolvent and creditors are hashing out a plan to sell the company’s remains.
“Take all future prediction on the future of the industry with a grain of salt,” Thaler says. “It’s all incredibly volatile and incredibly experimental. But that said, we’re closer to being 10 years out now than we were 10 years ago.”