More Arctic Methane Bubbles into Atmosphere - Scientific American
There, the underwater permafrost serves as a cap over methane in the seafloor. The permafrost is thawing, though and losing its ability to hold in the methane.
"Thus, methane could release in large amounts," Shakhova said.
In deeper parts of the ocean, the methane released from the ocean floor would likely never make it up to the atmosphere, since it would get used up by microbes before it reached the surface.
However, on the shelf where Shakhova measured methane releases, the shallowness of the sea and the fact that methane is released as bubbles mean that it rises quickly to the surface and escapes into the atmosphere.
Storms bring up more methane
Pulses of the methane bubbles are often triggered by storms, which churn up the water and allow the bubbles to quickly make their way up to the surface, the study found. Storms are already common in the area and may increase with climate change, leading to more methane pulses.
Shakhova's research team used sonar to target bubbles of methane rising up from the seafloor. They calculated the amount of methane being released from the bubbles to the atmosphere at 17 teragrams per year, which is close to the amount being released from the Arctic tundra.
More plumes observed in the Arctic Ocean breaking surface in 2014.