GoKawiilSaleem Ali, an environmental systems scientist at the University of Delaware who also provides research and advice on critical metals to the United Nations, says that deep-sea mining should be part of discussions on the green transition. He coauthored a 2022 analysis, funded by The Metals Company, that compared mining waste from terrestrial deposits to that of seabed resources. (Ali says he has never received direct funding from The Metals Company.) For example, the analysis looked at the impact of terrestrial mine tailings on water pollution and local biodiversity, and at the anticipated pollution from nodule mining, such as seabed sediment kicked into the water column by harvesting machines. It suggests that both types of mining will have effects on biodiversity, but deep-sea mining could result in less waste and fewer risks for communities than terrestrial mining. The study cautions, however, that its conclusions are limited by “substantial uncertainty” regarding impacts of sediment plumes.
Ali adds that the International Seabed Authority has been collecting data for at least 30 years, which should be sufficient to develop rules and regulations to govern seabed mining even if it’s unclear what the long-term impacts are, and whether the environmental impacts are likely to be better or worse than mining on land.
“I’m not saying that we should go ahead with it. I’m saying that it deserves to be considered in this broad context of very difficult choices we have to make,” he says.
But opponents calling for moratoriums or bans note that the same study that The Metals Company refers to as evidence of quick recovery eventually reached more pessimistic conclusions from its data as a whole. “The effects of polymetallic nodule mining are likely to be long term,” the authors wrote, and the analyses “show considerable negative biological effects of seafloor nodule mining, even at the small scale of test mining experiments.” Scientists are concerned that deep-sea organisms, which are adapted to living in a dark, quiet, and sparsely populated environment, will not cope well with the noise and light disturbances from mining. The organisms will also be exposed to toxic metals and plumes of sediment that can interfere with feeding and breathing. The Metals Company did not respond to several requests for comment.
Credit: ROV TEAM / GEOMAR (CC-BY 4.0) The seafloor of Clarion-Clipperton Zone is home to many creatures, some of which are shown here: anemone (top left), sea cucumber, Psychropotes longicauda (top right), sea urchin Plesiodiadema sp. (bottom right), and starfish (bottom left). The biology and ecology of these depths remain poorly understood, making it hard to know what the ecological impacts of deep-sea mining would be. The seafloor of Clarion-Clipperton Zone is home to many creatures, some of which are shown here: anemone (top left), sea cucumber, Psychropotes longicauda (top right), sea urchin Plesiodiadema sp. (bottom right), and starfish (bottom left). The biology and ecology of these depths remain poorly understood, making it hard to know what the ecological impacts of deep-sea mining would be. Credit: ROV TEAM / GEOMAR (CC-BY 4.0)