Slow Down, Cool Down: Reducing Methane From Coastal Shipping - CleanTechnica

The article highlights a recently recognized source of methane emissions linked to large ships operating in shallow coastal waters. Research shows that vessels with draughts over nine meters traveling faster than 12 knots can disturb organic-rich seabed sediments, releasing methane—a potent greenhouse gas with a global warming potential 82.5 times that of CO₂ over 20 years. Field measurements near Neva Bay, Russia, confirmed measurable methane release caused by such ship activity. While oceanic cargo ships mostly transit deep waters and thus generate negligible methane emissions from sediment disturbance, large coastal vessels like cruise ships, roll-on/roll-off (roro), and ropax ferries frequently operate in shallow, sediment-rich zones, making their methane emissions more significant. The article also notes that dredging in major ports disturbs methane-rich sediments, causing episodic methane releases, but these events are infrequent and minor compared to the overall maritime carbon footprint. Although methane emissions from coastal shipping and dredging are currently small relative to the billion