Methane (CH4) emissions from climate‐sensitive ecosystems within the northern permafrost region represent a potentially large but highly uncertain source, with current estimates spanning a factor of seven (11–75 Tg CH4 yr−1). Accelerating permafrost thaw threatens significant increases in pan‐Arctic CH4 emissions, amplifying the permafrost carbon feedback. We used airborne imaging spectroscopy with meter‐scale spatial resolution and broad coverage to identify a previously undiscovered CH4 emission hotspot adjacent to a thermokarst lake in interior Alaska. Hotspot emissions were confined to <1% of the 10 ha lake study area. Ground‐based chamber measurements confirmed average daily fluxes from the hotspot of 1,170 mg CH4 m−2 d−1, with extreme daily maxima up to 24,200 mg CH4 m−2 d−1. Ground‐based geophysical measurements revealed thawed permafrost directly beneath the CH4 hotspot, extending to a depth of ∼15 m, indicating that the intense CH4 emissions likely originated from recently thawed permafrost. Hotspot emissions accounted for ∼40% of total diffusive CH4 emissions from the lake study site. Combining study site findings with hotspot statistics from our 70,000 km2 airborne survey across Alaska and northwestern Canada, we estimate that pan‐Arctic terrestrial thermokarst hotspots currently emit 1.1 (0.1–5.2) Tg CH4 yr−1, or roughly 4% of the annual pan‐Arctic wetland budget from just 0.01% of the northern permafrost land area. Our results suggest that significant proportions of pan‐Arctic CH4 emissions originate from disproportionately small areas of previously undetermined thermokarst emissions hotspots, and that pan‐Arctic CH4 emissions may increase non‐linearly as thermokarst processes increase under a warming climate.

Methane (CH 4 ) release to the atmosphere from thawing permafrost contributes significantly to global CH 4 emissions. However, constraining the effects of thaw that control the production and emission of CH 4 is needed to anticipate future Arctic emissions. Here are presented robust rate measurements of CH 4 production and cycling in a region of rapidly degrading permafrost. Big Trail Lake, located in central Alaska, is a young, actively expanding thermokarst lake. The lake was investigated by taking two 1 m cores of sediment from different regions. Two independent methods of measuring microbial CH 4 production, long term (CH 4 accumulation) and short term ( 14 C tracer), produced similar average rates of 11 ± 3.5 and 9 ± 3.6 nmol cm −3 d −1 , respectively. The rates had small variations between the different lithological units, indicating homogeneous CH 4 production despite heterogeneous lithology in the surface ~1 m of sediment. To estimate the total CH 4 production, the CH 4 production rates were multiplied through the 10-15 m deep talik (thaw bulb). This estimate suggests that CH 4 production is higher than emission by a maximum factor of ~2, which is less than previous estimates. Stable and radioactive carbon isotope measurements showed that 50% of dissolved CH 4 in the first meter was produced further below.Interestingly, labeled 14 C incubations with 2-14 C acetate and 14 C CO 2 indicate that variations in the pathway used by microbes to produce CH 4 depends on the age and type of organic matter in the sediment, but did not appear to influence the rates at which CH 4 was produced. This study demonstrates that at least half of the CH 4 produced by microbial breakdown of organic matter in actively expanding thermokarst is emitted to the atmosphere, and that the majority of this CH 4 is produced in the deep sediment.

Our Moon periodically moves through the magnetic tail of the Earth that contains terrestrial ions of hydrogen and oxygen. A possible density contrast might have been discovered that could be consistent with the presence of water phase of potential terrestrial origin. Using novel gravity aspects (descriptors) derived from harmonic potential coefficients of gravity field of the Moon, we discovered gravity strike angle anomalies that point to water phase locations in the polar regions of the Moon. Our analysis suggests that impact cratering processes were responsible for specific pore space network that were subsequently filled with the water phase filling volumes of permafrost in the lunar subsurface. In this work, we suggest the accumulation of up to ~ 3000 km3 of terrestrial water phase (Earth’s atmospheric escape) now filling the pore spaced regolith, portion of which is distributed along impact zones of the polar regions of the Moon. These unique locations serve as potential resource utilization sites for future landing exploration and habitats (e.g., NASA Artemis Plan objectives).

In this paper, we review both practical and theoretical assessments for evaluating radon geohazards from permafrost landforms in northern environments (>60º N). Here, we show that polar amplification (i.e. climate change) leads to the development of thawing permafrost, ground subsidence, and thawed conduits (i.e. Taliks), which allow radon migration from the subsurface to near surface environment. Based on these survey results, we conjecture that abruptly thawing permafrost soils will allow radon migration to the near surface, and likely impacting human settlements located here. We analyze potential geohazards associated with elevated ground concentrations of natural radionuclides. From these results, we apply the main existing legislation governing the control of radon parameters in the design, construction and use of buildings, as well as existing technologies for assessing the radon hazard. We found that at present, these laws do not consider our findings, namely, that increasing supply of radon to the surface during thawing of permafrost will enhance radon exposure, thereby, changing prior assumptions from which the initial legislation was determined. Hence, the legislation will likely need to respond and reconsider risk assessments of public health in relation to radon exposure. We discuss the prospects for developing radon geohazard monitoring, methodical approaches, and share recommendations based on the current state of research in permafrost effected environments.

This paper describes a five-month experiment (February – July 2021) measuring the gradual thaw diffusion of radon-222 (further in the article – radon) from a frozen environment in NW Russia (i.e. Arhangelsk region). Red clay substrate containting a high content of 226Ra filled the bottom insides of 200-liter barrel holding the source of radon and buried at 1.6 m depth (e.g., the radium source zone), then covered with native soil, filled with water and frozen under in-situ conditions. Radon measurements were carried out from soil surface above the container (disturbed soil layer) and at background location (undisturbed soil layer). Several periods of increased radon flux density were observed, which was related to radium source zone thawing. It was shown that in 1-2 days after thawing of the radium source zone and drying of the upper soil layer, the radon flux increases sharply – more than 8 times compared to background values. These results show a strong relationship between radon flux density and soil temperature profiles at different depths. The calculations of radon sourced from frozen and thawed zones show how temperature phase of substrate (e.g. clays) control the barrier influence of radon migration. It reduced them by 10-20 times (according to the results of a theoretical calculation), depending on the characteristics of frozen rocks (density, porosity). Thus, the barrier function of permafrost is related to the physical properties of ice and frozen rocks. These temperture phases controls radon emanation coefficients and significantly influences the migration of radon to the earth’s surface.