In a groundbreaking study, researchers have uncovered a hidden source of methane emissions that’s been under our noses, or rather, under our keels. Amanda T. Nylund, a researcher from the Department of Mechanics and Maritime Sciences at Chalmers University of Technology, has shed light on how ship passages can trigger significant methane emissions in coastal and estuarine areas. The findings, published in the journal ‘Communications Earth & Environment’ (translated from ‘Communications Earth & Environment’ to ‘Communications Earth & Environment’ for English readers), could have substantial implications for the maritime industry and climate change mitigation efforts.
So, what’s the deal? Well, it turns out that the pressure changes and water column mixing caused by ships can induce methane emissions through processes like diffusion or ebullition. In plain English, that means ships can stir up and release methane that’s been trapped in the seabed. Nylund and her team found that these ship-triggered emissions are no small potatoes. In Neva Bay, for instance, the estimated methane flux was a whopping 11.1 millimoles per square meter per day. That’s 10 to 1,000 times higher than the global average for estuarine and coastal areas, and on par with some of the most significant aquatic methane emission hotspots.
The pressure changes caused by ships, ranging from 30 to 60 millibars, are comparable to those induced by tidal changes. This means that every time a ship passes through a coastal or estuarine area, it could be triggering a significant release of methane. Nylund explains, “Our results indicate that ship-induced pressure changes trigger methane emission, comparable with observed emissions induced by tidal pressure changes.”
But why should the maritime industry care? For starters, these emissions contribute to climate change. Methane is a potent greenhouse gas, with a warming potential about 25 times greater than carbon dioxide over a 100-year period. The study found that ship-triggered methane emissions corresponded to a 22% increase in emitted carbon dioxide equivalents compared to the combustion-related exhausts from ships. That’s a significant chunk of additional greenhouse gases that we hadn’t accounted for until now.
So, what can be done? Well, for one, this study highlights the need to include shipping lanes when assessing estuarine and coastal methane emissions. It’s a gap in our current emission inventories that needs to be filled. Moreover, the maritime industry could explore ways to mitigate these emissions. This could involve adjusting shipping routes to avoid sensitive areas, developing ship designs that minimize pressure changes, or even investing in technologies that capture and utilize the released methane.
The findings also present an opportunity for the maritime industry to contribute to climate change mitigation efforts. By acknowledging and addressing this issue, the industry can demonstrate its commitment to sustainability and potentially gain a competitive edge. After all, in today’s world, environmental responsibility is not just a nice-to-have, but a must-have.
In the meantime, researchers like Nylund will continue to delve into this complex issue, unraveling the intricacies of ship-triggered methane emissions and helping the maritime industry navigate these uncharted waters. So, the next time you’re out at sea, remember, it’s not just the waves you’re making that matter. It’s the bubbles too.