To the mining firms vying to extract them, on the other hand, they promise to be a "battery in a rock."
These nodules, found on the seafloor several kilometers below the surface, are to be the subject of the first submarine mining contract application, which the government of Nauru is expected to soon submit to the International Seabed Authority (ISA).
The contract is for Nori, Nauru Ocean Resources Inc, a subsidiary of Canada's The Metals Company.
This has caused concern among conservationists and scientists, who fear the severe impacts of mining a relatively untouched region of the planet that is rich in life, much of which remains unknown to science.
- Ancient -
Polymetallic nodules are most abundant in the Clarion-Clipperton Zone (CCZ) -- off the west coast of Mexico in the Pacific -- as well as in the central Indian Ocean and in the Peruvian Basin, according to the ISA.
The nodules were probably formed over millions of years.
They likely started off as solid fragments -- perhaps a shark tooth -- that sank down to the soft muddy seabed, then grew slowly through the accumulation of minerals present in the water in extremely low concentrations.
Today, they reach up to 20 centimeters (nearly 8 inches) in size: "metal pebbles," according to the French Research Institute for Exploitation of the Sea.
Adrian Glover, of Britain's Natural History Museum, thinks of them as like "potatoes" scattered on the seabed, roughly 15 to 20 kilograms (33 to 44 pounds) of them per square meter.
One of the reasons why the nodules have never been buried under the mud in the Pacific is because the sea is food poor, with fewer dead organisms -- known as "marine snow" -- drifting down to the depths to eventually become part of the seafloor mud.
Sedimentation rates in some areas of the CCZ are "almost zero", Glover said, amounting to just a centimeter per thousand years.
The nodules were first recovered from the Pacific deep in the 1870s by the Challenger expedition, which used thousands of meters of hemp rope, a steam-powered winch and plenty of manpower to dredge the westerly part of the CCZ.
"Straightaway they realized they were very interesting, it was actually one of the biggest discoveries of the voyage for them," said Glover.
But they were not considered to be a "resource," he added.
- 'Clean' power? -
Some 20 companies or research centers have been awarded exploration contracts by the ISA for these nodules. One of these is Nori, whose contract covers four zones totalling some 75,000 square kilometers (about 30,000 square miles) in the CCZ.
These nodules are mainly composed of manganese and iron, but they also contain strategic minerals such as cobalt, nickel and copper.
According to the ISA, the CCZ contains around 21 billion metric tons of nodules, which could correspond to a reserve of six billion metric tons of manganese, 270 million metric tons of nickel and 44 million metric tons of cobalt, exceeding the known totals of these three minerals on land.
Advocates of undersea mining point to their potential use for green technology, particularly for electric vehicles.
"A battery in a rock," says The Metals Company.
"Polymetallic nodules are the cleanest path toward electric vehicles."
But that is an argument rejected by environmental NGOs and some scientists.
This claim is "more public relations than scientific fact", Michael Norton, of the European Academies' Science Advisory Council, told AFP, calling it "rather misleading" to say that demand cannot be met without undersea minerals.
- Impact fears -
Unlike the other two types of subsea mining resources regulated by the ISA -- including the mining of hydrothermal vents -- nodules do not require digging or cutting.
In tests carried out at the end of 2022, Nori lowered a collector vehicle to a depth of 4.3 kilometers (about 2.7 miles).
It swallowed nodules and sediment and then separated them, transporting the nodules to the surface vessel via a giant pipe and discharging the sediment into the water.
Catherine Weller, global policy director at the conservation organization Fauna & Flora, said that while the nodules are lying on the seafloor, they cannot just be "plucked" individually.
The impacts on the wider ocean system of churning up sediment and releasing wastewater was "simply unknown," she added.
Weller said the unique composition of the nodules which attracts mining firms is also what makes them such a special habitat for the creatures that live in the ocean depths.
"So they themselves are a really important part of the deep sea system."
'Fight is on' at deep sea mining debate in Jamaica
United Nations, United States (AFP) July 26, 2023 -
Nations opposed to deep sea mineral mining and those in favor of exploiting the oceans' depths butted heads in Jamaica on Wednesday, with both sides arguing their position would help protect the planet.
Members of the International Seabed Authority (ISA), a little-known global body tasked with regulating the vast ocean floor, are locked in a heated debate over the future of deep sea mining at their annual meeting in Kingston.
"We cannot and must not embark on a new industrial activity when we are not yet able to fully measure its consequences, and therefore risk irreversible damage to our marine ecosystems," said Herve Berville, French secretary of state for seas.
"Our responsibility is immense, and none of us in this room will be able to say that we were unaware of the collapse of marine biodiversity, the rise in sea level or the sudden increase in ocean temperature," he warned during a debate.
This year's meeting, set to end Friday, comes after a July 9 deadline triggered by the small Pacific state of Nauru.
That legal step has created a new pressure to adopt a deep sea mining code and given fuel to opponents who hope to block the practice outright.
The ISA is made up of 168 member states, as well as the European Union.
Under the UN Convention on the Law of the Sea (UNCLOS), the body is responsible both for protecting the seabed in areas beyond national jurisdiction and for overseeing any exploration or exploitation of resources in those zones.
Some countries want to hurry up and begin retrieving the rock-like "nodules" scattered across the seafloor, which contain minerals important to battery production such as nickel, cobalt and copper.
"We have a window of opportunity to support the development of a sector that Nauru considers has the potential to help accelerate our energy transition to combat climate change," argued the island nation's president Russ Joseph Kun.
But NGOs and scientists say that trawling the deep seas could destroy habitats and species that may still be unknown or potentially vital to ecosystems.
They also say it risks disrupting the ocean's capacity to absorb carbon dioxide emitted by human activities, and that its noise interferes with the communication of species such as whales.
Around twenty countries, including France, have asked for a "precautionary pause" on deep sea mining, and have recently gained some political momentum.
Greenpeace's Louisa Casson hailed new calls by Brazil and Canada for such a moratorium, telling AFP that "cracks are appearing in what has to date been a fortress for industry interests."
But several countries have resisted hitting the pause button, notably China, which has succeeded thus far in blocking any official debate on the matter.
Mark Brown, the prime minister of the Cook Islands, argued that the "global community needs to use every tool at its disposal" to fight climate change.
But he called for any path forward to be done "responsibly and sustainably for the longterm wellbeing of our people and the preservation of our unique marine environment."
- 'Legal vacuum' -
The ISA Council, the decision-making body on contracts, has previously given out several permits for seabed exploration, but with the passing of the July 9 deadline, any member state can now apply for a mining contract for a company it sponsors.
Last week, the 36-member Council gave itself the target of adopting the mining code in 2025, but without agreeing on how to examine contract requests in the meantime, prompting criticism of a "legal vacuum."
Nonetheless, Nauru says it will apply "soon" for a contract for Nori, a subsidiary of Canada's The Metals Company, which seeks to harvest "polymetallic nodules" in the Clarion-Clipperton fracture zone (CCZ) in the Pacific.
In March, however, the ISA Council noted that commercial exploitation "should not be carried out" until a mining code was in place.
The Deep Sea Conservation Coalition's Sofia Tsenikli said Wednesday that Nauru's "ultimatum has not worked out."
"The mining code is far from developed and the majority of states in the council have stated their opposition to mining in the absence of regulations," she added.
Casson of Greenpeace, for her part, viewed the latest developments optimistically, saying "the world is fighting back against deep sea mining."
"There's a big fight ahead, but the fight is on."
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