A new source of methane – a greenhouse gas many times more powerful than carbon dioxide – has been identified by scientists flying over areas in the Arctic where the sea ice has melted.
The researchers found significant amounts of methane being released from the ocean into the atmosphere through cracks in the melting sea ice. They said the quantities could be large enough to affect the global climate. Previous observations have pointed to large methane plumes being released from the seabed in the relatively shallow sea off the northern coast of Siberia but the latest findings were made far away from land in the deep, open ocean where the surface is usually capped by ice.
Eric Kort of Nasa's Jet Propulsion Laboratory in Pasadena, California, said that he and his colleagues were surprised to see methane levels rise so dramatically each time their research aircraft flew over cracks in the sea ice.
"When we flew over completely solid sea ice, we didn't see anything in terms of methane. But when we flew over areas were the sea ice had melted, or where there were cracks in the ice, we saw the methane levels increase," Dr Kort said. "We were surprised to see these enhanced methane levels at these high latitudes. Our observations really point to the ocean surface as the source, which was not what we had expected," he said.