Abstract Thawing of permafrost due to climate change is known to release gases such as the climate drivers carbon dioxide and methane, as well as the carcinogen radon. Gas permeability is extremely low in fully frozen permafrost and can be considered both to function as a seal preventing subsurface gases being released, and to prevent the creation of new CO 2 and CH 4 . However, the permeability of permafrost as it thaws and refreezes is unknown. In this paper we present initial measurements of changes in gas fraction and gas permeability during the thawing of synthetic permafrost using a newly developed pycno‐permeameter. Initial results show that gas permeability increases by multiple orders of magnitude (from 4.94 mD to 112.54 mD and from 0.26 mD to 21.43 mD for our two samples), depending on the initial water saturation of the sample, with most permeability change occurring in the −5°C to −1°C range. Upon refreezing, the permeability drops again to approximately its previous low values providing no water is allowed to drain from the sample, but with a hysteresis. Measurements of gas fraction show a similar variation to thawing and refreezing but with a hysteresis opposite to that for permeability. These initial results indicate that the protective gas seal previously provided by permafrost will be lost as permafrost thaws. These data are also able to inform large scale permafrost modeling, as well as suggesting that thawing and refreezing operate differently at a microstructural level.
Glover et al. (Sun,) studied this question.