The Moon controls the tides that shape our shores. Tides, in turn, significantly affect the intensity of methane emissions from the Arctic Ocean seabed.
This is the conclusion of a new study published in Nature Communications, dedicated to analyzing how huge amounts of this powerful greenhouse gas are being released into the atmosphere from the Arctic , and that they could be intensified by a warmer ocean in the future.
The possibility that this gas escapes from the ocean and contributes to the balance of greenhouse gases in the atmosphere is a major mystery that scientists are trying to solve.
The total amount of methane in the atmosphere has increased enormously in recent decades, and although part of the increase can be attributed to human activity, other sources are not very limited.
“We note that gas accumulations, found in sediments one meter from the seabed, are vulnerable to even slight pressure changes in the water column . Low tide means less hydrostatic pressure and a higher intensity of methane release. High tide equates to high pressure and less intensity of release, ”says article co-author Andreia Plaza Faverola, from UiT The Arctic University of Norway.
“This is the first time this observation has been made in the Arctic Ocean . It means that slight changes in pressure can release significant amounts of methane . This is a game changer and the biggest impact of the study, ”says another co-author Jochen Knies.
Plaza Faverola notes that the observations were made by placing a tool called a piezometer in the sediments and leaving it there for four days.
He measured the pressure and temperature of the water within the pores of the sediment. Hourly changes in measured pressure and temperature revealed the presence of gas near the seafloor that rises and falls as the tides change. The measurements were made in an area of the Arctic Ocean where methane release had not been previously observed but where massive concentrations of gas hydrates were sampled .
“This tells us that the release of gas from the seabed is more widespread than we can see with traditional sonars. We did not see bubbles or gas plumes in the water. Gas burps that have a periodicity of several hours will not be identified unless there is a permanent monitoring tool, such as the piezometer, ”says Plaza Faverola.
These observations imply that the quantification of current gas emissions in the Arctic may be underestimated . However, high tides seem to influence gas emissions by reducing their height and volume.
“What we found was unexpected and the implications are great. This is a deep water site. Small changes in pressure can increase gas emissions, but the methane will remain in the ocean due to the depth of the water. “
But what happens in less deep places. “This approach should also be done in shallow Arctic waters, for a longer period . In shallow waters, the chance of methane reaching the atmosphere is higher, ”says Knies.
Therefore, high sea level appears to influence gas emissions by potentially reducing their height and volume. The question remains whether sea level rise due to global warming could partially offset the effect of temperature on subsea methane emissions.
“Earth’s systems are interconnected in ways that we are still figuring out, and our study reveals one of those interconnections in the Arctic: the Moon causes tidal forces, tides generate pressure changes, and bottom currents in turn give it forms the seabed and impacts underwater methane emissions. Fascinating!” says Andreia Plaza Faverola./Europa Press