It may not be very well known, but enormous amounts of the potent greenhouse gas methane are released in the Arctic Ocean.
These leaks have existed for thousands of years, but could be compounded by a warmer ocean in the future. The potential of this gas to escape the ocean and add to the greenhouse gas budget in the atmosphere is a major puzzle scientists are trying to solve.
The total amount of methane in the atmosphere has increased immensely over the past few decades, and while some of the increase is due to human activity, other sources are not very limited.
A paper recently published in Nature Communications even implies that the moon plays a role.
Small changes in pressure affect the methane release
The moon controls one of the greatest forces in nature – the tides that shape our coasts. Tides, in turn, have a significant impact on the intensity of methane emissions from the sea floor of the Arctic Ocean.
“We have found that accumulations of gas in the sediments within one meter of the seabed are subject to even slight changes in pressure in the water column. Low tide means less such hydrostatic pressure and higher intensity of methane release. High tide equals high tide pressure and lesser intensity Publication, “says co-author of the newspaper Andreia Plaza Faverola.
“This is the first time this observation has been made in the Arctic Ocean. This means that small changes in pressure can release significant amounts of methane. This is a cornerstone and the highest impact of the study.” Says another co-author, Jochen Knies.
New methods reveal unknown release sites
Plaza Faverola indicates that the observations were made by placing a tool called a piezometer in the sediments and leaving it there for four days.
The pressure and temperature of the water in the pores of the sediment were measured. Hourly changes in measured pressure and temperature indicated the presence of gas near the sea floor, rising and falling with changing tides. The measurements were taken in an area of the Arctic Ocean where no methane release was previously observed, but where massive gas hydrate concentrations were measured.
“This shows us that the gas release from the ocean floor is more widespread than we can see with traditional sonar surveys. We did not see any bubbles or columns of gas in the water. Gas burps with a periodicity of several hours are only identified there is a permanent monitoring tool like the piezometer. “Says Plaza Faverola
These observations suggest that the quantification of today’s gas emissions in the Arctic may be underestimated. However, floods appear to affect gas emissions by reducing their height and volume.
“What we found was unexpected and the impact is great. This is a deep water location. Small changes in pressure can increase gas emissions, but the methane still stays in the ocean because of the depth of the water. But what happens at shallower locations?” This approach has to last a long time Period can also be carried out in shallow arctic waters. In shallow waters, methane is more likely to get into the atmosphere, “says Knies.
Can counteract the effects of temperature
High sea levels therefore appear to affect gas emissions by potentially reducing their height and volume. The question remains whether sea level rise due to global warming could partially offset the influence of temperature on methane emissions from submarines.
“Earth systems are interconnected in ways that we have yet to decipher, and our study shows one of those connections in the Arctic: the moon creates tidal forces, the tides create pressure changes and bottom currents, which in turn shape the ocean floor and affect submarine methane Emissions. Fascinating! “Says Andreia Plaza Faverola
The paper is the result of a collaboration between CAGE, Center for Arctic Gas Hydrate, Environment and Climate at UiT of the Arctic University of Norway, and Ifremer as part of the project SEAMSTRESS – Tectonic Stress Effects on Arctic Methane Leaching
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