NASA scientists have used planes equipped with specialist infrared imaging to study 20,000 square miles of Arctic landscape to detect methane hotspots.
Rising temperatures are causing permafrost to thaw, releasing methane and other greenhouse gases into the atmosphere, but scientists had to find a way of measuring it.
Scientists from NASA’s Arctic Boreal Vulnerability Experiment used planes equipped with the Airborne Visible Infrared Imaging Spectrometer – Next Generation to fly over the remote Arctic landscape to detect the hotspots.
Areas exceeding 3,000 parts per million of methane between the airborne sensor and the ground are classed as hotspots, and two million were detected.
In the paper, Airborne Mapping Reveals Emergent Power Law of Arctic Methane Emissions, it was also found that hotspots were mostly concentrated about 44 yards (40m) from standing bodies of water.
After 44 yards, the presence of hotspots becomes sparser and drop off almost completely about 330 yards from the water source.
Scientists do not know why 44 is the magic number but Clayton Elder of NASA’s Jet Propulsion Laboratory in Pasadena, California, says ground field studies at an Alaskan lake with a methane hotspot showed abrupt thawing of permafrost right underneath the hotspot.
He said: “It’s that additional contribution of permafrost carbon – carbon that’s been frozen for thousands of years – that’s essentially contributing food for the microbes to chew up and turn into methane as the permafrost continues to thaw.”
Scientists say that identifying the likely causes of the distribution of methane hotspots will help them more accurately calculate greenhouse gas emissions across areas where observations were previously unavailable.
The knowledge will improve how Arctic land models represent methane dynamics and forecasting the region’s impact on global climate and climate change’s impact on the Arctic.
Elder said, “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.”