Methane leaks multiplying beneath Antarctic ocean spark fears of climate doom loop
A powerful greenhouse gas has begun seeping from the Antarctic seafloor into dozens of locations, scientists have discovered.
Researchers documented the emergence of these methane seeps in shallow regions of the Ross Sea, a bay off the southern coast of Antarctica. Gas leaks could be caused by global warming, and they could also threaten to accelerate it further, according to a new study published October 1 in the journal Natural communications.
“If they follow the behavior of other global seepage systems, there is the potential for rapid transfer of methane to the atmosphere from a source that is not currently considered in future climate change scenarios,” Seabrook added.
Methane (CH4) is a greenhouse gas which traps heat in the atmosphere by absorbing outgoing radiation. When methane first enters the atmosphere, it is much more effective at trapping heat than carbon dioxide (CO2), being approximately 80 times more powerful during the first 20 years, it’s in the atmosphere. This makes methane a particularly aggressive driver of short-term climate change. (CO2 stays in the atmosphere longer, so it’s a more important long-term driver.)
About 60% of methane emissions come from human activities such as agriculture and the burning of fossil fuels, while the remaining 40% comes from natural sources. Scientists fear that as the planet warms, more natural sources of methane and carbon dioxide, such as those in melting permafrostare being unlocked, creating a positive feedback loop that accelerates warming even further.
Researchers have already spotted tens of thousands of methane leaks in the Arctic, but before the new study, there was only one confirmed methane leak in the Antarctic, identified in 2011. Underwater seeps create streams of bubbles when methane and other chemicals dissolve in ocean water after being released beneath the seafloor. White mats of microbial communities live around the seeps, making them identifiable on the seafloor.
In the new study, researchers used acoustic surveys, divers and a remotely operated vehicle to explore seeps located between 16 feet (5 meters) and 787 feet (240 m) below the icy surface of the Ross Sea, off the Antarctic continent. The team initially studied just one seep at Cape Evans, located on the west side of Ross Island, and were surprised to find that the seafloor was littered with them.
“Last year we went to Cape Evans to look at a small area where gas bubbles had been discovered and we were hoping to find that site still bubbling,” Seabrook said. “Instead, we found dozens more.”
The researchers studied areas that have been regularly studied for decades, meaning the seeps must be something new. It’s unclear exactly what causes these seeps to appear, but researchers noted that similar processes in the Arctic and paleo-records (past environments) have been attributed to climate-driven cryospheric change – the breakdown of land ice that previously locked these chemicals in place.
It’s not clear how much methane might leave Antarctica and reach our atmosphere, or how much remains trapped under the melting ice, but researchers fear the seeps could be widespread. This raises fears of positive feedback loops as well as various other impacts caused by methane, such as ocean acidification.
Seabrook and his colleagues recommended coordinated international efforts to urgently study the seeps.
“If these seeps continue to appear in the areas we’re working in, it really raises the question of what Antarctica’s shallow coastal environment might look like in five or 10 years,” Seabrook said. “This system is evolving rapidly before our eyes from one year to the next.”
