NASA scientists at the US space agency’s Jet Propulsion Laboratory (JPL) in California are claiming that cracks in frozen parts of the Arctic Ocean’s surface could be leading to increased emissions of the greenhouse gas methane, created by living organisms near the ocean’s surface.
Their findings were published in Nature Geoscience yesterday.
Eric Kort, a JPL post-doctoral scholar who is affiliated with the Keck Institute of Space Studies at California Institute of Technology, led the analysis of the Arctic and methane levels while he was a student at Harvard University between 2009 and 2010.
What the scientists have discovered is that cracks in part of the Arctic Ocean’s frozen surface could be responsible for increased methane levels in the region.
As the Earth’s climate warms, the scientists are claiming that methane, which is frozen in reservoirs stored in Arctic tundra soils or marine sediments, can be more likely to get released into the atmosphere.
Kort’s team collected atmospheric measurements from the Earth’s surface to an altitude of 14 kilometres during five flights using a specially instrumented Gulfstream V aircraft in 2009 and 2010.
The National Science Foundation in the US was the primary funder of the scientific mission.
Understanding climate change
The scientists said they observed increased methane levels of about 0.5pc larger than normal background levels while flying at low altitudes over the remote Arctic Ocean, north of the Chukchi and Beaufort Seas.
They compared locations of the enhanced methane levels with airborne measurements of carbon monoxide, water vapour and ozone. As a result, the scientists said they pinpointed a source for the elevated methane levels: the ocean surface, through cracks in Arctic sea ice and areas of partial sea ice cover.
The scientists said they detected no carbon monoxide in the atmosphere that would point to possible cause from human activity.
They also said that, based on the time of year, location and nature of the emissions, it was very unlikely the methane was coming from high-latitude wetlands or geologic reservoirs. And the scientists also said they detected no enhanced methane levels when flying over areas of solid ice.
What’s behind the methane production?
According to Kort, biological production from living organisms in the Arctic surface waters may be behind the methane production.
"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," he said.
"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," added Kort.