Arctic Seafloor Releasing 17 Teragrams of Methane Every Year, Study Finds

The Arctic seafloor might have a larger methane time-bomb than previously assumed.

A new study has found that the East Siberian Arctic Shelf is releasing 17 teragrams of methane each year, about twice as much as previous estimates. One teragram is about 1 million tons. What's worse is that climate change might be accelerating its release.

The study was conducted by researchers at the University of Alaska, Fairbanks and colleagues.

Methane is the second-most prevalent greenhouse gas in the environment, according to Environmental Protection Agency. Although methane's lifespan (about 10 years)  in the environment is shorter than carbon dioxide, it traps more heat.

In the seabed, the greenhouse gas is stored as methane hydrates. The arctic permafrost acts like a cap, preventing methane from escaping into the atmosphere. Increasing temperatures are now thawing these caps, allowing the gas to escape.

The East Siberian Arctic Shelf is three times larger than the nearby Siberian wetlands, which was once considered to be a primary source of methane. Previous research had suggested that ESAS was releasing about 8 teragrams of the gas annually.

 "It is now on par with the methane being released from the arctic tundra, which is considered to be one of the major sources of methane in the Northern Hemisphere," said Natalia Shakhova, one of the paper's lead authors and a scientist at the University of Alaska Fairbanks, according to a news release. "Increased methane releases in this area are a possible new climate-change-driven factor that will strengthen over time."

Shakhova and Igor Semiletov, both researchers at the UAF International Arctic Research Center, have found that the subsea permafrost in the area has thawed much more extensively than previous estimates. They attribute the thinning to higher oceanic temperature. Also, frequent storms in the area have allowed a lot of methane to escape.

During their research expedition, the team used a variety of techniques, including sonar, seafloor drilling and water sampling to assess the condition of the permafrost and the amount of methane being released, according to the news release

The study is published in the journal Nature Geoscience.

U.S. Methane Levels Exceed Previous Estimates

Another recent study on methane has found that the U.S. is releasing more methane than current estimates.

The study conducted by Harvard University researchers found that South Central United States- centers of fossil fuel extraction and refining activities- are releasing quite a lot of methane, about five times larger than government estimates.

This study is published in the journal of Proceedings of the National Academy of Sciences (PNAS),