20,000 Feet Under The Sea
The Atlantic|January - February 2020
The bottom of the ocean is as alien as Mars: a dark, mysterious place with purple octopuses, giant tube worms, and who knows what else. Mining companies are preparing to extract minerals that could wean the Earth from fossil fuels, but scientists have never explored many of the habitats they might destroy. The race between miners and scientists may determine the fate of the oceans, and the planet.
by Wil.S. Hylton

Unless you are given to chronic anxiety or suffer from nihilistic despair, you probably haven’t spent much time contemplating the bottom of the ocean. Many people imagine the seabed to be a vast expanse of sand, but it’s a jagged and dynamic landscape with as much variation as any place onshore. Mountains surge from under water plains, canyons slice miles deep, hot springs billow through fissures in rock, and streams of heavy brine ooze down hillsides, pooling into undersea lakes.

These peaks and valleys are laced with most of the same minerals found on land. Scientists have documented their deposits since at least 1868, when a dredging ship pulled a chunk of iron ore from the seabed north of Russia. Five years later, another ship found similar nuggets at the bottom of the Atlantic, and two years after that, it discovered a field of the same objects in the Pacific. For more than a century, oceanographers continued to identify new minerals on the seafloor—copper, nickel, silver, platinum, gold, and even gemstones—while mining companies searched for a practical way to dig them up.

Today, many of the largest mineral corporations in the world have launched underwater mining programs. On the west coast of Africa, the De Beers Group is using a fleet of specialized ships to drag machinery across the seabed in search of diamonds. In 2018, those ships extracted 1.4 million carats from the coastal waters of Namibia; in 2019, De Beers commissioned a new ship that will scrape the bottom twice as quickly as any other vessel. Another company, Nautilus Minerals, is working in the territorial waters of Papua New Guinea to shatter a field of under water hot springs lined with precious metals, while Japan and South Korea have embarked on national projects to exploit their own offshore deposits. But the biggest prize for mining companies will be access to international waters, which cover more than half of the global seafloor and contain more valuable minerals than all the continents combined.

Regulations for ocean mining have never been formally established. The United Nations has given that task to an obscure organization known as the International Seabed Authority, which is housed in a pair of drab gray office buildings at the edge of Kingston Harbour, in Jamaica. Unlike most UN bodies, the ISA receives little oversight. It is classified as “autonomous” and falls under the direction of its own secretary general, who convenes his own general assembly once a year, at the ISA headquarters. For about a week, delegates from 168 member states pour into Kingston from around the world, gathering at a broad semicircle of desks in the auditorium of the Jamaica Conference Centre. Their assignment is not to prevent mining on the seafloor but to mitigate its damage—selecting locations where extraction will be permitted, issuing licenses to mining companies, and drafting the technical and environmental standards of an underwater Mining Code.

Writing the code has been difficult. ISA members have struggled to agree on a regulatory framework. While they debate the minutiae of waste disposal and ecological preservation, the ISA has granted “exploratory” permits around the world. Some 30 mineral contractors already hold licenses to work in sweeping regions of the Atlantic, Pacific, and Indian Oceans. One site, about 2,300 miles east of Florida, contains the largest system of underwater hot springs ever discovered, a ghostly landscape of towering white spires that scientists call the “Lost City.” Another extends across 4,500 miles of the Pacific, or roughly a fifth of the circumference of the planet. The companies with permits to explore these regions have raised breathtaking sums of venture capital. They have designed and built experimental vehicles, lowered them to the bottom, and begun testing methods of dredging and extraction while they wait for the ISA to complete the Mining Code and open the floodgates to commercial extraction.

At full capacity, these companies expect to dredge thousands of square miles a year. Their collection vehicles will creep across the bottom in systematic rows, scraping through the top five inches of the ocean floor. Ships above will draw thousands of pounds of sediment through a hose to the surface, remove the metallic objects, known as polymetallic nodules, and then flush the rest back into the water. Some of that slurry will contain toxins such as mercury and lead, which could poison the surrounding ocean for hundreds of miles. The rest will drift in the current until it settles in nearby ecosystems. An early study by the Royal Swedish Academy of Sciences predicted that each mining ship will release about 2 million cubic feet of discharge every day, enough to fill a freight train that is 16 miles long. The authors called this “a conservative estimate,” since other projections had been three times as high. By any measure, they concluded, “a very large area will be blanketed by sediment to such an extent that many animals will not be able to cope with the impact and whole communities will be severely affected by the loss of individuals and species.”

At the ISA meeting in 2019, delegates gathered to review a draft of the code. Officials hoped the document would be ratified for implementation in 2020. I flew down to observe the proceedings on a balmy morning and found the conference center teeming with delegates. A staff member ushered me through a maze of corridors to meet the secretary general, Michael Lodge, a lean British man in his 50s with cropped hair and a genial smile. He waved me toward a pair of armchairs beside a bank of windows overlooking the harbor, and we sat down to discuss the Mining Code, what it will permit and prohibit, and why the United Nations is preparing to mobilize the largest mining operation in the history of the world.

Until recently, marine biologists paid little attention to the deep sea. They believed its craggy knolls and bluffs were essentially barren. The traditional model of life on Earth relies on photosynthesis: plants on land and in shallow water harness sunlight to grow biomass, which is devoured by creatures small and large, up the food chain to Sunday dinner. By this account, every animal on the planet would depend on plants to capture solar energy. Since plants disappear a few hundred feet below sea level, and everything goes dark a little farther down, there was no reason to expect a thriving ecosystem in the deep. Maybe a light snow of organic debris would trickle from the surface, but it would be enough to sustain only a few wayward aquatic drifters.

That theory capsized in 1977, when a pair of oceanographers began poking around the Pacific in a submersible vehicle. While exploring a range of underwater mountains near the Galápagos Islands, they spotted a hydrothermal vent about 8,000 feet deep. No one had ever seen an underwater hot spring before, though geologists suspected they might exist. As the oceanographers drew close to the vent, they made an even more startling discovery: A large congregation of animals was camped around the vent opening. These were not the feeble scavengers that one expected so far down. They were giant clams, purple octopuses, white crabs, and 10-foot tube worms, whose food chain began not with plants but with organic chemicals floating in the warm vent water.

For biologists, this was more than curious. It shook the foundation of their field. If a complex ecosystem could emerge in a landscape devoid of plants, evolution must be more than a heliological affair. Life could appear in perfect darkness, in blistering heat and a broth of noxious compounds—an environment that would extinguish every known creature on Earth. “That was the discovery event,” an evolutionary biologist named Timothy Shank told me. “It changed our view about the boundaries of life. Now we know that the methane lakes on one of Jupiter’s moons are probably laden with species, and there is no doubt life on other planetary bodies.”

Shank was 12 years old that winter, a bookish kid in North Carolina. The early romance of the space age was already beginning to fade, but the discovery of life near hydrothermal vents would inspire a blossoming of oceanography that captured his imagination. As he completed a degree in marine biology, then a doctorate in ecology and evolution, he consumed reports from scientists around the world who found new vents brimming with unknown species. They appeared far below the surface—the deepest known vent is about three miles down—while another geologic feature,​ known as a “cold seep,” gives rise to life in chemical pools even deeper on the seafloor. No one knew how far down the vents and seeps might be found, but Shank decided to focus his research on the deepest waters of the Earth.

Scientists divide the ocean into five layers of depth. Closest to the surface is the “sunlight zone,” where plants thrive; then comes the “twilight zone,” where darkness falls; next is the “midnight zone,” where some creatures generate their own light; and then there’s a frozen flatland known simply as “the abyss.” Oceanographers have visited these layers in submersible vehicles for half a century, but the final layer is difficult to reach. It is known as the “hadal zone,” in reference to Hades, the ancient Greek god of the underworld, and it includes any water that is at least 6,000 meters below the surface— or, in a more Vernian formulation, that is 20,000 feet under the sea. Because the hadal zone is so deep, it is usually associated with ocean trenches, but several deepwater plains have sections that cross into hadal depth.

Deepwater plains are also home to the polymetallic nodules that explorers first discovered a century and a half ago. Mineral companies believe that nodules will be easier to mine than other seabed deposits. To remove the metal from a hydrothermal vent or an underwater mountain, they will have to shatter rock in a manner similar to land-based extraction. Nodules are isolated chunks of rocks on the seabed that typically range from the size of a golf ball to that of a grapefruit, so they can be lifted from the sediment with relative ease. Nodules also contain a distinct combination of minerals. While vents and ridges are flecked with precious metal, such as silver and gold, the primary metals in nodules are copper, manganese, nickel, and cobalt—crucial materials in modern batteries. As iPhones and laptops and electric vehicles spike demand for those metals, many people believe that nodules are the best way to migrate from fossil fuels to battery power.

The ISA has issued more mining licenses for nodules than for any other seabed deposit. Most of these licenses authorize contractors to exploit a single deepwater plain. Known as the Clarion- Clipperton Zone, or CCZ, it extends across 1.7 million square miles between Hawaii and Mexico—wider than the continental United States. When the Mining Code is approved, more than a dozen companies will accelerate their explorations in the CCZ to industrial-scale extraction. Their ships and robots will use vacuum hoses to suck nodules and sediment from the seafloor, extracting the metal and dumping the rest into the water. How many ecosystems will be covered by that sediment is impossible to predict. Ocean currents fluctuate regularly in speed and direction, so identical plumes of slurry will travel different distances, in different directions, on different days. The impact of a sediment plume also depends on how it is released. Slurry that is dumped near the surface will drift farther than slurry pumped back to the bottom. The circulating draft of the Mining Code does not specify a depth of discharge. The ISA has adopted an estimate that sediment dumped near the surface will travel no more than 62 miles from the point of release, but many experts believe the slurry could travel farther. A recent survey of academic research compiled by Greenpeace concluded that mining waste “could travel hundreds or even thousands of kilometers.”

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