The race is on to figure out how to protect the ocean abyss as deep-sea mining operations look to extract minerals like nickel, cobalt, and copper from the sea floor. But there’s one potential risk to the deep-sea environment that tends to fall under the radar. Not only will mining dredge up the seafloor, but it’ll also create a lot of noise that poses its own problems for marine life, according to a newly published paper in the journal Science.
People have talked about mining the deep sea for minerals for decades, and that future is almost here. Driven by a need for more of the minerals used in everyday gadgets and batteries, the first efforts to raid polymetallic nodules at the bottom of the ocean for these resources could begin in earnest as soon as next year. The noise from those operations could affect marine life even hundreds of kilometers away, the authors of the new paper found.
Louder than a rock concert
Within about 6 kilometers (3.73 miles) of a mine, the noise could be equivalent to or even louder than a rock concert. That exceeds the threshold, 120 dB, that the US National Marine Fisheries Service says could negatively impact marine mammals’ behavior. The noise travels up to 500 kilometers (310 miles) away, where it would weaken but still be louder than ambient noise levels during fair weather.
“The biggest surprise for me was how far ambient noise levels are likely to be exceeded,” says Craig Smith, one of the authors of the paper and a professor of oceanography at the University of Hawai‘i. To make things worse, the noise from mining could be nonstop. “This noise is expected to be produced 24/7 for years or maybe even decades,” Smith tells The Verge.
And unlike the noise at busy ports that’s mostly at the surface of the water, mining creates a racket all the way down to the bottom of the seafloor. There’s noise from vessels above, dredges below, and pumps that bring nodules and sediments up to the surface.
As a result, whales passing through might have a harder time communicating. Or whales and other animals might decide to avoid these areas altogether, which could even affect their migration.
Still, researchers don’t know exactly how that will affect marine life — and a big part of the problem is that there’s still so much that we don’t yet know about life in the ocean’s abyss. The vast majority of animals researchers bring up from expeditions to these depths — 4,000 meters (13,123 feet) or deeper — are completely new to science, according to Smith.
There are crustaceans, worms, mollusks, anemones, and more — and Smith would like to see more research into how sensitive these creatures are to noise. Without sunlight at these depths, some animals have developed sensory systems that allow them to use vibrations or noise to avoid predators or find mates and prey.
Smith and his colleagues made predictions based on models since mining hasn’t started, and they couldn’t take real-world observations. They focused on a region that might soon be a hotspot for deep-sea mining called the Clarion-Clipperton Zone, which lies between Hawaii and Mexico. That zone is rich in polymetallic nodules, lumpy black rock-like things on the seafloor that contain metals that are increasingly sought after to make EV batteries.
Last year, the small island nation of Nauru announced plans to sponsor an effort to mine the Clarion-Clipperton Zone. That triggered a clause in the United Nations Convention on the Law of the Sea that requires the International Seabed Authority to craft new regulations for mining the nodules by the middle of next year.
Since then, hundreds of scientists have pushed to stop mining until they have a better understanding of what it might do to the surrounding environment. Last week, the leaders of some island nations — including Palau, Fiji, and Samoa — also called for a moratorium on deep-sea mining. Mining digs up and buries seafloor habitats. Rushing into it without a good understanding of the risks, they warn, might even wipe out ecologically important species before they’ve even been discovered.
Smith and his co-authors are also urging mining contractors to release more data on the sound from their mining equipment. Moving forward over the next year “without data transparency and rigorous standards and guidelines in place would represent the start of a large-scale, uncontrolled experiment,” the paper says.