Arctic Ocean a newly discovered source of methane

A new multi-institution study has found the Arctic Ocean to be a surprising source of methane being emitted into the atmosphere. It has been understood for some time that the Arctic tundra is vulnerable to huge emissions of stored methane as the surface melts, but this is the first time methane from the ocean has been shown to be entering the atmosphere.

The study was part of the HIAPER Pole to Pole Observations (HIPPO), which recorded a number of measurements of the Arctic and its Ocean in an airborne campaign spanning the whole globe.

The team involved found that in several flights over the region from 2009 to 2010, increased methane levels were present at low altitudes. This was only around half a per cent greater than background levels, but this small yet significant variation was enough to peak the interest of the researchers.

They ruled out human combustion and high latitude wetlands or geologic reservoirs. Instead they found the methane was escaping through cracks in the ice, as methane escaped from the water beneath. It has been known that methane can build up in surface waters, but this is the first time they have been shown to escape into the atmosphere. This is likely to be down to biological organisms in the ocean producing the gas.

NASA’s Eric Kort says, "It's possible that as large areas of sea ice melt and expose more ocean water, methane production may increase, leading to larger methane emissions." Indeed, further studies will be required to determine just how much of an effect on the atmosphere these emissions have, and how they change with climate.

"While the methane levels we detected weren't particularly large, the potential source region, the Arctic Ocean, is vast, so our finding could represent a noticeable new global source of methane," he added. "As Arctic sea ice cover continues to decline in a warming climate, this source of methane may well increase. It's important that we recognize the potential contribution from this source of methane to avoid falsely interpreting any changes observed in Arctic methane levels in the future."