STOCKHOLM, June 2 — Fjords release large amounts of methane. According to a recent Swedish study, methane emissions at the surface of the fjords are equivalent to those of all the deep oceans around the world. This phenomenon is linked to mixing of water layers from these bodies of water that flow into these dizzying U-shaped valleys.
Often associated with cattle breeding or organic waste, methane is also hidden within one of the most impressive types of natural formations in the world: fjords. While Norway is home to some of the most breathtaking of such formations, they are also found in Sweden, Iceland, Greenland and Canada.
And some of them emit significant quantities of methane, the second most potent greenhouse gas after carbon dioxide, as confirmed in the first part of the sixth IPCC report published in August 2021. According to a study from the University of Gothenburg in Sweden, published in Limnology and Oceanography Letters, methane emissions at the surface of fjords are of the same magnitude as emissions from global deep oceans. However, fjords represent about 0.13 per cent of the world’s seas, while deep oceans account for 84 per cent.
One fjord cited in particular is By Fjord, located near the city of Uddevalla in Sweden. A team of researchers conducted a field study of the formation during the period between 2009 and 2021, to measure methane emissions in this fjord.
“This is because the distance from the bottom to the surface of a fjord is much shorter than in deep oceans.in fjords, carbon-rich sediment is deposited from marine plants and animals as well as from materials entering the fjords from the surrounding land via streams that flow into them. As fjords are relatively protected from ocean currents, the water tends to remain stratified in layers at different temperatures and with different concentrations of salt and oxygen,” explains Stefano Bonaglia, co-author of the study.
“This results in more organic matter being deposited in the sediment, and not enough time for the methane to be broken down on its way up to the surface,” adds the researcher, researcher in marine geochemistry at the Department of Marine Sciences at the University of Gothenburg.
The fjord analyzed in this research is not an isolated case. The observations obtained from this study are consistent with those made by American researchers, who have also found high methane emissions in Canadian fjords.
If climate change leads to more extreme weather events, methane emissions could increase, the researcher warns, though only 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,” he notes. — ETX Studio
