In the remote northern Arctic, greenhouse gas emissions are slipping through the icy cracks.
Flying over some of the most inaccessible parts of Alaska and northwestern Canada, NASA researchers have located a shocking amount of thawing permafrost – the frozen layer of soil that blankets much of the region.
If this tundra melts, it releases methane and other carbon emissions into the atmosphere, further accelerating global warming.
Today, we know the Arctic is warming twice as fast as any other place on Earth, but given how frigid and formidable landscape the landscape is, we still don’t know where the most methane is being emitted.
“We consider hotspots to be areas showing an excess of 3,000 parts per million of methane between the airborne sensor and the ground,” says Earth system scientist Clayton Elder from NASA’s Jet Propulsion Laboratory.
“And we detected 2 million of these hotspots over the land that we covered.”
If that sounds like a lot more than we knew about, you’d be right. For many months of the year, much of the Arctic is inaccessible to scientists, so ground-based observations have covered a mere fraction of the region so far.
While other airborne studies in the past have also noticed Arctic permafrost is melting faster than we thought, NASA researchers see this new technology as a breakthrough, giving us an entirely new perspective on the region.
Using a unique infrared spectrometer (known as AVIRIS-NG), researchers gathered over 400 data runs from flights undertaken in July and August of 2017, covering some 30,000 square kilometres of Arctic land (12,000 square miles).
In total, the trips gathered roughly a billion careful observations on methane emissions, and the results reveal a clear pattern of dispersal centred around water.
“AVIRIS-NG has been used in previous methane surveys, but those surveys focused on human-caused emissions in populated areas and areas with major infrastructure known to produce emissions,” says Elder.
“Our study marks the first time the instrument has been used to find hotspots where the locations of possible permafrost-related emissions are far less understood.”
Analysing the results, the authors settle on a ‘magic number’ for methane hotspots. On average, they say, these spots are clustered along the banks of lakes, ponds, streams, and other wetland features, usually within 30 to 40 metres (44 yards).
From there on out, the hotspots begin to fade, becoming sparser as they grow more distant from the liquid, until finally, they disappear almost completely, roughly 300 metres (330 yards) away.
See more details: sciencealert.com