Fjords Emit as Much Methane as All the Deep Oceans Globally
hubie writes:
Fjords emit as much methane as all the deep oceans globally
The world's fjords were created when the inland ice receded, and are a relatively rare natural feature, constituting only 0.13 per cent of all the oceans on Earth. However, according to researchers from the University of Gothenburg, emissions of methane from the surface of fjords are comparable to the emissions of this gas from global deep oceans which account for 84 per cent of the global sea surface area. These results were presented in an article in the prestigious science journal Limnology and Oceanography Letters.
"It's been known for some time that many fjords have anoxic environments closest to the bottom and that methane forms in the bottom sediment. Usually, only a small portion of this gas ever reaches the atmosphere because it gets broken down as it ascends through the more oxygen-rich waters closer to the surface. But in our research, we recorded large emissions of methane when the water in the fjord was mixed during storm events, for example," says Stefano Bonaglia, researcher in marine geochemistry at the Department of Marine Sciences at the University of Gothenburg.
[The lead author] adds that if climate change leads to more extreme weather events, methane emissions may rise, but only up to a certain point.
"If we were to see a sharp rise in the number of heavy storm events, methane emissions would be reduced, because the anoxic environments at the bottom of fjords would disappear if the water are mixed frequently."
Journal Reference:
Stefano Bonaglia et al., High methane emissions from an anoxic fjord driven by mixing and oxygenation [open], Limnol Oceanogr, 2022. DOI: 10.5061/dryad.ksn02v75g
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