During five research flights in 2009 and 2010, Kort and colleagues measured enhanced methane levels while flying at low altitudes north of the Chukchi and Beaufort Seas. Over open water the team detected methane levels about one-half percent higher than normal background levels; over solid ice, they did not enhanced levels of the gas.
They inferred that the cracks were allowing methane in the top layers of the sea to escape into the atmosphere, in part by ruling out two other potential sources. First, if the methane had been coming from burning of fossil fuels, the team would have detected excess carbon monoxide as well (but they did not). And second, the time of year, location and nature of the emissions made high-latitude wetlands or geologic reservoirs unlikely.
"While the methane levels we detected weren't particularly large, the potential source region, the Arctic Ocean, is vast," Kort said in a summary posted on the NASA Earth Observatory. "Our finding could represent a noticeable new global source of methane."