Jul 19, 2017

Strong geologic methane emissions from discontinuous terrestrial permafrost in the Mackenzie Delta, Canada

Katrin Kohnert, Andrei Serafimovich, Stefan Metzger, Jörg Hartmann, Torsten Sachs
Scientific Reports
  • States that Arctic permafrost caps vast amounts of old, geologic methane (CH4) in subsurface reservoirs
  • States that thawing permafrost opens pathways for this CH4 to migrate to the surface; however, the occurrence of geologic emissions and their contribution to the CH4 budget in addition to recent, biogenic CH4 is uncertain
  • Presents a high-resolution (100 m × 100 m) regional (10,000 km²) CH4 flux map of the Mackenzie Delta, Canada, based on airborne CH4 flux data from July 2012 and 2013
  • Identifies strong, likely geologic emissions solely where the permafrost is discontinuous; such peaks are 13 times larger than typical emissions due to microbial production
  • Notes that, whereas microbial CH4 production largely depends on recent air and soil temperature, geologic CH4 was produced over millions of years and can be released year-round provided open pathways exist; therefore, even though they only occur on about 1% of the area, geologic hotspots contribute 17% to the annual CH4 emission estimate of the study area
  • Suggests that this share may increase if ongoing permafrost thaw opens new pathways