The ocean has always been a noisy place. Waves, rain, and the low grumble of the seafloor form a soundscape that marine animals have evolved with for millions of years. What is new is the volume of the human contribution — and its persistence.
Commercial shipping has roughly doubled the low-frequency background noise in the North Atlantic since the 1960s. The sound travels for hundreds of kilometers, masking the calls that whales use to find each other across entire basins.
An experiment nobody designed
Researchers are now using the pause in shipping during the pandemic as a natural experiment. Underwater recorders that had been running for years captured an abrupt quiet, and then a gradual return. The data is some of the clearest evidence yet that noise changes animal behavior.
We can measure the noise. We are much worse at measuring what it silences.
The next pressure is seabed mining, which would add a new and poorly understood industrial sound to some of the least-studied places on Earth. Regulators are drafting noise limits with almost no baseline data. Scientists argue that the baseline is the experiment — and it is already running.
