BUENOS AIRES: Scientists have discovered an active methane seepage from the Antarctic seabed that could shed light on the powerful greenhouse gas trapped beneath the frozen continent.
Marine ecologist Andrew Thurber first glimpsed what a colleague described as a “microbial cascade” during a dive in the icy waters of the Ross Sea in 2012. What looked like a superhighway of white patches on the ocean floor were clusters of small organisms attracted to methane leakage.
“My first thought was ‘wow’ and I immediately fell in love with what this means for science,” said Thurber, an assistant professor at Oregon State University.
Scientists believe that there is a large amount of methane stored under the ocean floor in Antarctica. The discovery, published Wednesday in the journal Proceedings of the Royal Society B, marks the first time a natural leak has been detected on the continent.
There is no evidence that climate change is behind the methane leak in Antarctica; good news for scientists concerned that global warming could cause permafrost to thaw and release long-trapped methane.
However, if methane reaches the atmosphere, it could exacerbate global warming because methane is a more potent greenhouse gas than carbon dioxide. Atmospheric methane levels have risen https://www.reuters.com/article/us-climate-change-methane/global-methane-emissions-rising-due-to-oil-and-gas-agriculture-studies-idUSKCN24F2X8 due to human activities, including agriculture and oil and gas drilling.
Thurber noted that the microbes found near the Antarctic seep actually help keep methane out of the atmosphere by consuming the gas before it can rise through the water into the air.
That won’t help mitigate man-made emissions, which account for at least half the methane in the atmosphere. Ocean sources of methane contribute only 1% of total global emissions.
Most of the previous research looking for natural underwater methane seeps has focused on depths of 200 to 600 meters, where the gas must pass through “many microbial mouths” before it can reach the atmosphere, Thurber said.
However, the leak in Antarctica was only 10 meters deep, putting methane on a fast track to the surface.
“Ten meters is not 600 meters. That methane can get into the atmosphere and start to become a potential player in methane budgets,” Thurber said.
Another concern, Thurber said, is that microbes in cold, shallow waters were slow to reach the methane seep from Antarctica, a finding that could help scientists better understand microbial behavior and whether it could help prevent the Methane that seeps elsewhere enters the atmosphere.
“We need to see them as systems that do not respond in a matter of days, an hour or a month, but on a time scale of years,” Thurber said. “As the years start to add up, that becomes something that can potentially affect our ability to predict our future planet.”
Karla Heidelberg, a microbial ecologist at the US-based National Science Foundation, said more methane leaks could be revealed as climate change causes oceans to warm and Antarctic ice sheets melt.
“As the ice cover changes, it could expose more of these seeps to become potential inputs of atmospheric carbon,” Heidelberg said.
Antarctica’s frozen methane reserves could end up being a “tipping point” with massive warming potential if disturbed, said Ben Poulter, an environmental scientist at NASA’s Goddard Space Flight Center.
“If they destabilize, you would have a massive pulse of methane in the atmosphere that would cause more climate change,” Poulter said.