Influence of permafrost thaw on an extreme geologic methane seep

• Published in: Permafrost and Periglacial Processes
• Main Authors: Sullivan, Taylor D., Parsekian, Andrew D., Sharp, Janelle, Hanke, Philip J., Thalasso, Frederic, Shapley, Mark, Engram, Melanie, Walter Anthony, Katey
• Other Authors: National Science Foundation
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2021
• Subjects: Arctic; permafrost; Permafrost and Periglacial Processes; Alaska
• Online Access: http://dx.doi.org/10.1002/ppp.2114; https://onlinelibrary.wiley.com/doi/pdf/10.1002/ppp.2114; https://onlinelibrary.wiley.com/doi/full-xml/10.1002/ppp.2114; https://onlinelibrary.wiley.com/doi/am-pdf/10.1002/ppp.2114

Abstract The occurrence and magnitude of natural fossil methane (CH 4 ) emissions in the Arctic are poorly known. Emission of geologic CH 4 , a potent greenhouse gas, originating beneath permafrost is of particular interest due to the potential for positive feedback to climate warming, whereby accelerated permafrost thaw releases permafrost‐trapped CH 4 in a future warmer climate. The development of through‐going taliks in Arctic lakes overlying hydrocarbon reservoirs is one mechanism of releasing geologically sourced, subpermafrost CH 4 . Here we use novel gas flux measurements, geophysical observations of the subsurface, shallow sediment coring, high‐resolution bathymetry measurements, and lake water chemistry measurements to produce a synoptic survey of the gas vent system in Esieh Lake, a northwest Alaska lake with exceedingly large geologic CH 4 seep emissions. We find that microbially produced fossil CH 4 is being vented though a narrow thaw conduit below Esieh Lake through pockmarks on the lake bottom. This is one of the highest flux geologic CH 4 seep fields known in the terrestrial environment and potentially the highest flux single methane seep. The poleward retreat of continuous permafrost may have implications for more subcap CH 4 release with increased permafrost thaw.