The bid to plunder one of the least explored territories on the planet should be reconsidered, given the potentially irreversible impact on marine habitats. Stripping the seabed also risks disturbing stores of carbon locked away for millennia, with unknown consequences for a jittery climate. The vast, cold, lightless ocean floor, with crushing pressures that can be more than a thousand times those on land, has been quietly eyed for its extractive promise since the 1960s.

One draw is the Clarion-Clipperton Zone, an area spanning at least 4.5mn square kilometres in the equatorial Pacific. The abyssal plain, more than 4km down, is studded with trillions of potato-sized “polymetallic nodules” containing manganese, nickel, copper and cobalt, which are used in rechargeable batteries for electric vehicles. The nodules build up around small objects such as shells or teeth over millions of years.

The region also features seamounts, or underwater mountains, draped in metal-heavy crusts; and sulphide ores laid down around hot, deep-sea vents. The crusts are rich in precious metals such as platinum and molybdenum; the ores contain copper, gold and silver. All are sought-after commodities in electronics, construction and transportation.  But these minerals are embedded in a marine infrastructure, built up over millennia and longer, which supports a mostly unwritten inventory of deep-sea life. Known inhabitants include sponges, sea cucumbers, octopi and xenophyophores, strange single-celled creatures the size of tennis balls.

Nematode worms and crustaceans nestle in the soft sea mud. Deep-sea mining would destroy these creatures and their habitats. Recovering the nodules involves skimming off the top layer of the sea floor; separating the nodules from the mud; pumping the nodules through a hose to an offshore vessel; and then pumping the remnants back in the sea.

Kirsten Thompson, an ecologist at Exeter University who has written reports on deep-sea mining with Greenpeace, questions whether the minerals really are as critical to the green revolution as portrayed, and argues against tearing into an environment we don’t understand. “Vast areas of the seabed might be changed forever, and we can’t restore it once it’s lost,” she tells me.

One downside could be losing microbes with medicinal potential; one marine-derived molecule, salinosporamide, is being trialled as a treatment for brain cancer.  The nodule-nabbers remain undeterred. In June 2021, the small state of Nauru informed the International Seabed Authority that it wanted to start mining; its application triggered the two-year countdown. The clock has run out; ISA will meet this month to discuss the next steps.

Norway, China and India favour deep-sea extraction; India is already exploring options in the nodule-rich Indian Ocean that promise self-sufficiency in nickel and cobalt. France and the UK hold exploration licences, as permitted by ISA, but do not currently support commercial mining, a stance that several other European countries share. Advocates argue that scraping minerals off the sea floor could break China and Russia’s control over critical raw materials; and that it can replace land mining, which is haunted by issues such as deforestation, child labour and the displacement of communities. But it seems optimistic to think that terrestrial mining will stop if costlier deep-sea mining starts.

Neither do issues of social justice dissolve at the bottom of the ocean: it is unclear how spoils will be shared, given the international seabed is the common heritage of humankind. More pragmatically, any industry needs customers — and companies such as BMW, Volvo and Samsung have pledged to keep minerals sourced in this way out of their supply chains.

Long-term, it seems wiser to try to break the global dependence on rare commodities than to perpetuate it. Research into new battery technologies is paying dividends; Tesla is already using cobalt-free batteries. There is a growing call for improved recycling. Given the unknown risks and uncertain benefits, deep-sea mining might prove a tricky concept to keep afloat.