Rapid increase of Antarctic methane seeps raises climate concerns

Antarctic methane seeps are rapidly increasing, raising alarm about a potentially underestimated source of greenhouse gas emissions.

Methane is a greenhouse gas that traps 80 times more heat than carbon dioxide over two decades, so scientists are investigating how these sources of methane may be connected to the warming climate, according to a statement released recently by Earth Sciences New Zealand.

Scientists have discovered over 40 new methane seep sites in the Ross Sea's shallow waters, indicating a fundamental shift in regional methane release around Antarctica, according to the research, which explores the emergence and discovery of these seeps in the shallow coastal environment of the continent.

"Methane seeps are areas of the seafloor where methane and other chemicals escape from reservoirs underneath the seabed and dissolve in the water, often having streams of bubbles that extend all the way up to the surface," said Earth Sciences New Zealand marine scientist Sarah Seabrook.

"The first was discovered by chance in 2012 and since then they've been cropping up at a remarkable rate," Seabrook said, adding a similar phenomenon has also been observed in the Arctic.

"Every time we discover or hear of a new one, we feel immediate excitement, but that excitement is quickly replaced with anxiety and concern about what it all means," said Seabrook, the lead author of the study published in Nature Communications in collaboration with the University of California, Santa Barbara, in the United States, and Australia's University of Tasmania.

Seabrook noted that if the Antarctic methane seeps follow the behavior of other global seep systems, there is potential for a rapid transfer of methane to the atmosphere from a source not currently accounted for in future climate change scenarios.

Using remotely operated vehicles and divers under the ice to search for new seeps, the research team, led by Seabrook, explored sites from about five to 240 meters deep. At Cape Evans on the west side of Antarctica's Ross Island, where a seep had been documented, they instead found dozens more.

"If these seeps keep emerging at the areas we are working in, it really begs the question of what the shallow coastal environment of Antarctica may look like five or 10 years from now. This system is rapidly changing before our eyes from one year to the next," Seabrook said.

The research group will return this season to survey more seep sites, though melting sea ice has made some areas, such as Cape Evans, inaccessible.