12-07-2025
Shipping traffic can trigger methane emissions from seafloor, study finds
Ships trigger seafloor methane emissions while moving through shallow water, researchers report in Communications Earth & Environment.
The scientists say the unexpected discovery has nothing to do with the type of fuel used by the ship. Instead, 'ship-induced pressure changes and turbulent mixing' trigger the release of the gas from the seafloor.
Bubbles and gas diffusion push the methane into the atmosphere, where it acts as a greenhouse gas.
Scientists had noticed unexpected methane emissions in the Baltic Sea's Neva Bay shipping lane while conducting other research, the researchers say in a 'Behind the Paper' article for Springer Nature Research Communities.
The team was in the 'right place at the right time, looking for everything else than methane plumes, but with a methane sensor they didn't expect to give any interesting signals,' they write.
But they did find methane — lots of it. Years later, they assembled an interdisciplinary team to solve the mystery.
It turns out the ships were triggering the emissions, filling the shipping lane with bubbles and causing the sediment below to release methane gas in periodic fluxes.
Container and cruise ships triggered the largest and most frequent methane emissions, but the study suggests that ships of all kinds, regardless of their type of engine or size, trigger methane emissions.
Researchers said they observed emissions that were 20 times higher in the shipping lane than in undisturbed nearby areas.
Given the number of ports in similarly shallow areas worldwide, it's important to learn more about emissions in shipping lanes and to better estimate their 'hitherto unknown impact,' study co-author Johan Mellqvist, a professor of optical remote sensing at Chalmers University of Technology in Sweden, said in a news release.
