Antarctica is estimated to have a quarter of the world’s marine methane stores. Methane, a dangerous greenhouse gas ( 25% more potent than the greenhouse gas CO2), accelerates global heating, aggravating the planetary climate emergency and collapse of biodiversity.
The first methane leak discovered in Antarctica is on the Wilkes Subglacial Basin seafloor near the Ross sea in East Antarctica. The hole has confirmed fears by researchers on the considerable contribution to our rapidly warming planet.
East Antarctica differs from West Antarctica (which is one of nine active climate tipping points) in that the vast majority of the ice sheet is on land. In the west, the vast majority of ice are marine extensions of enormous glaciers that hold back the inland glaciers from pouring ice into the ocean, raising global sea levels. The Wilkes Basin glaciers do not have a large scale retreat in their glacial history.
Oregon State University’s presser reports on the leak and notes that active marine seeps rely on microbes to consume methane at the source, preventing methane from bubbling up from the seafloor and into the atmosphere.
The Ross Sea seep was discovered in an area that scientists have studied for more than 60 years, but the seep was not active until 2011, said Thurber, an assistant professor in Oregon State's College of Earth, Ocean, and Atmospheric Sciences and the College of Science's Department of Microbiology.
An expansive microbial mat, about 70 meters long by a meter across, formed on the seafloor about 10 meters below the frozen ocean surface. These mats, which are produced by bacteria that exist in a symbiotic relationship with methane consumers, are a telltale indication of the presence of a seep, said Thurber.
“What was really interesting and exciting was that the microbial community did not develop as we would have predicted based on other methane seeps we have studied around the globe,” she said.
Researchers had assumed that microbes should respond really quickly to changes in the environment, but that wasn't reflected in what OSU's team saw in Antarctica, Thurber said.
“To add to the mystery of the Antarctic seeps, the microbes we found were the ones we least expected to see at this location,” he said. There may be a succession pattern for microbes, with certain groups arriving first and those that are most effective at eating methane arriving later.
“We've never had the opportunity to study a seep as its forming or one in Antarctica, because of this discovery we can now uncover whether seeps just function differently in Antarctica or whether it may take years for the microbial communities to become adapted,” Thurber said.
The researchers said that the reason for the leak at the Cinder Cones is a mystery because it is not in a part of the ocean that has been warming. The reaction of undersea microbes is much more concerning. It has been shown in prior researches that the microbes undersea prevent the methane from making its way to the surface and into the atmosphere as the microbes move in and eat it when other parts of the seafloor begin releasing methane.
They note that the methane-eating microbes have not moved into Cinder Cones, though it has has been leaking for at least five years. Therefore, the methane is almost certainly making its way into the atmosphere. They point out the reason this is so concerning because it suggests that microbes may not move into the area quickly enough to prevent massive amounts of the gas from making its way into the atmosphere if other parts of the seafloor in Antarctica begin to seep methane due to warming.
Researchers say that it could take as long as five more years for microbes to move in, and they plan to continue monitoring seepage at Cinder Cones. However, as the pandemic has put their plans on hold, that research will have to wait.
Research on this phenomenon is critical to our understanding of the methane cycle and it will need to be incorporated into climate change models.