Deep sea mining is poised to boost worldwide production of clean energy technology, but the potential harm it could do to the ocean environment in the process has still yet to be determined. Small rocks known as polymetallic nodules cover vast areas of the ocean floor, and their contents could be worth trillions of dollars, with numerous nations now making plans to excavate them.

The nodules hold a variety of rare earth elements, such as cobalt, nickel, manganese, copper, and even small amounts of lithium. These resources, the production of which has largely been dominated by China to date, are crucial for building electric vehicle (EV) batteries at a time when getting more battery-powered cars on the road is among the top priorities of climate agendas around the world.

“[Plans by automakers to sell hundreds of millions of EVs] are meaningless without the metals necessary to build these batteries,” said Dmitry Silversteyn, a senior analyst at Water Tower Research. “This is the biggest, the cleanest, the least environmentally impactful and most economical resource for nickel, manganese and cobalt that we know of.”

Mining executives have referred to the nodules as a “battery in a rock” due to the resources contained within them. Gerard Barron, CEO of The Metals Company, estimates that the amount found in just a fraction of the Pacific Ocean’s seafloor could power about 280 million EVs, a number nearly equivalent to the entire U.S. fleet of cars.

“The West has woken up to the fact that decades of outsourcing the supply – and the negative impacts – of key energy transition metals to Chinese-funded sources has left it vulnerable to disruption,” Barron said. “Given nobody wants a mine in their backyard, the ability to ship this abundant resource directly to the U.S. offers a rare opportunity to re-shore these critical supply chains, and support battery-related industries at home.”

While prospectors have also promoted deep sea mining as a more ethical form of mineral extraction that could help eliminate the child labor violations linked to some terrestrial mines, concerns remain about how clean the process of obtaining these rare earths will be, and who will benefit most from it.

China currently holds 5 of the 31 exploration licenses that the International Seabed Authority has issued so far, the most of any country, giving the country exclusive rights to excavate an area of ocean floor about the size of the United Kingdom. Chinese ships have already been seeking additional mineral deposits in the Pacific, Indian and Arctic Oceans.

“China is probably the single most active country in the [International Seabed Authority],” said Peter Dutton, a professor of international law at the U.S. Naval War College. “One of the things that the Chinese are doing very effectively is engaging in the rulemaking, and writing regulations that can favor their interests. They’re out there ahead of us, and that’s one area we need to be concerned about.”

About 95% of the worldwide production of rare earths are already controlled by China, with the nation also producing three quarters of all the globe’s lithium-ion batteries, which are used to power EVs. Experts worry that if China can be become a dominant player in seabed mining, then Beijing could control a vast supply of many key minerals needed for emerging industries like clean energy.

“If China can take the lead in seabed mining, it really has the lock on access to all the key minerals for the 21st-century green economy,” said Carla Freeman, senior expert for China at the United States Institute of Peace.

Meanwhile, China is not the only nation with a keen interest in mining the ocean floor. Countries like Norway and Japan are looking at their own coastal resources, further increasing the scale of this potentially harmful practice.

Some environmentalists believe deep sea mining will disrupt the world’s largest natural carbon sink, responsible for absorbing one-third of all carbon dioxide generated on land. The mining platforms, machinery and ships needed for these projects will also add to noise and pollution that can harm marine life. Additionally, the process of excavating the sea floor could cause harm to a variety of aquatic ecosystems.

“By impacting on natural processes that store carbon, deep sea mining could even make climate change worse by releasing carbon stored in deep sea sediments or disrupting the processes which help scavenge carbon and deliver it to those sediments,” Greenpeace said in a 2019 report.

“Sucking up nodules would involve destruction of the seabed, leading to the potential extinction of species. The nodules themselves support complex ecosystems, which would be lost,” the Deep Sea Conservation Coalition said. “Stripping seamounts of the outer layer of ‘crusts’ containing cobalt and other metals would destroy deep sea sponge and coral ecosystems that are likely to have taken thousands of years to grow. Noise, light pollution, and sediment plumes could seriously impact species, such as whales, that use noise, echolocation or bioluminescence to communicate, find prey and escape predators.”

These are issues the International Seabed Authority will have to contend with as its council continues drafting rules for deep sea mining. The intergovernmental body has restricted the commencement of any mining operations on the sea floor until the adoption of regulations can be completed. Member states have agreed to a goal of doing so by 2025.