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Manganese nodule. via Wikipedia

World - Deep-Sea Mining: How to Balance Need for Metals with Ecological Impacts

As the industry inches closer to reality, scientists probe potential environmental harms

Slashing humanity’s reliance on fossil fuels will require billions of kilograms of metal: a single wind turbine can contain more than a metric ton of copper, and electric car batteries demand heaps of cobalt, nickel and manganese. Most of these metals now come from terrestrial mines—often at the cost of deforestation, water pollution and human rights abuses. But a vast trove of metals on the deep-sea floor could soon provide an alternative source.

Though companies have been eyeing this possibility for decades, engineering challenges and unfavorable economics have kept work in the exploration phase. There has also been a lack of international rules to govern the nascent industry. But that is poised to change soon: The United Nations–chartered International Seabed Authority (ISA) has been finalizing regulations for commercially extracting deep-sea metals in international waters. These rules could emerge within a year. The inherent tension in setting them lies in balancing economic interests in metal production with another consideration: the potential for environmental damage.

Proponents say deep-sea mining can avoid a few of the ills of land-based extraction and cut the costs of renewable technology. But some scientists caution against jumping from exploration to exploitation too quickly, given how little we know about the deep-sea environment and the life it supports. “I generally don’t think it’s possible for us to objectively assess all the risks involved right now,” says Jeff Drazen, a marine biologist at the University of Hawaii at Manoa. “This is the poorest-described ecosystem on the planet.”

ENTICING PRIZE AT A VAST DEPTH

Interest in deep-sea minerals focuses largely on one particular resource: polymetallic nodules. These potato-sized deposits are rich in manganese, copper, cobalt and nickel. They form over millions of years as dissolved metals precipitate around the nuclei of organic materials—often ancient shark teeth, according to Antje Boetius, a marine biologist at the Max Planck Institute for Marine Microbiology in Bremen, Germany. She says these nodules are scattered in many areas across the global seafloor. They are especially plentiful in a vast swath of the ocean’s abyssal plain that stretches from Hawaii to Mexico and is called the Clarion-Clipperton Zone (CCZ). Nodules in the CCZ alone contain more nickel and cobalt than all known land-based reserves of those metals.

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