The Circumpolar Active Layer Monitoring (CALM) network is an ongoing international effort to collect and disseminate standardized measurements of active-layer dynamics to monitor the response of near-surface permafrost parameters to climate change. This work presents a distillation of 25 years (1995–2019) of observations from three north–south transects of CALM sites in tundra environments of Alaska. Transects examined in this work bisect tundra regions of discontinuous permafrost on the Seward Peninsula, and the continuous permafrost zone on the western and eastern sections of the Arctic Foothills and Arctic Coastal Plain. These transects represent regional climatic gradients, several physiographic provinces, and regionally characteristic landcover associations. Total active-layer thickening at observed sites ranged from 7 to 26 cm; more significant thaw occurred in the foothills despite less pronounced warming air temperature trends. This summary highlights several regional active layer responses to climate warming, complicated by distinct thermal landscape sensitivities, landscape variability, and documented thaw subsidence. Data summarized in this report are publicly available and represent an important validation resource for earth-system models that include regions in the continuous and discontinuous permafrost zones of northern and western Alaska.

Landscape drying associated with permafrost thaw is expected to enhance microbial methane oxidation in arctic soils. Here we show that ice-rich, Yedoma permafrost deposits, comprising a disproportionately large fraction of pan-arctic soil carbon, present an alternate trajectory. Field and laboratory observations indicate that talik (perennially thawed soils in permafrost) development in unsaturated Yedoma uplands leads to unexpectedly large methane emissions (35–78 mg m⁻² d⁻¹ summer, 150–180 mg m⁻² d⁻¹ winter). Upland Yedoma talik emissions were nearly three times higher annually than northern-wetland emissions on an areal basis. Approximately 70% emissions occurred in winter, when surface-soil freezing abated methanotrophy, enhancing methane escape from the talik. Remote sensing and numerical modeling indicate the potential for widespread upland talik formation across the pan-arctic Yedoma domain during the 21^st and 22^nd centuries. Contrary to current climate model predictions, these findings imply a positive and much larger permafrost-methane-climate feedback for upland Yedoma.

Evidences of highly localized methane fluxes are reported from the Arctic shelf, hot spots of methane emissions in thermokarst lakes, and are believed to evolve to features like Yamal crater on land. The origin of large methane outbursts is problematic. Here we show, that the biogenic methane (¹³C ≤ −71‰) which formed before and during soil freezing is presently held in the permafrost. Field and experimental observations show that methane tends to accumulate at the permafrost table or in the coarse-grained lithological pockets surrounded by the sediments less-permeable for gas. Our field observations, radiocarbon dating, laboratory tests and theory all suggest that depending on the soil structure and freezing dynamics, this methane may have been displaced downwards tens of meters during freezing and has accumulated in the lithological pockets. The initial flux of methane from the one pocket disclosed by drilling was at a rate of more than 2.5 kg C(CH₄) m⁻² h⁻¹. The age of the methane was 8–18 thousand years younger than the age of the sediments, suggesting that it was displaced tens of meters during freezing. The theoretical background provided the insight on the cryogenic displacement of methane in support of the field and experimental data. Upon freezing of sediments, methane follows water migration and either dissipates in the freezing soils or concentrates at certain places controlled by the freezing rate, initial methane distribution and soil structure.

The gas shows in the permafrost zone represent a hazard for exploration, form the surface features, and are improperly estimated in the global methane budget. They contain methane of either surficial or deep-Earth origin accumulated earlier in the form of gas or gas hydrates in lithological traps in permafrost. From these traps, it rises through conduits, which have tectonic origin or are associated with permafrost degradation. We report methane fluxes from 20-m to 30-m deep boreholes, which are the artificial conduits for gas from permafrost in Siberia. The dynamics of degassing the traps was studied using static chambers, and compared to the concentration of methane in permafrost as analyzed by the headspace method and gas chromatography. More than 53 g of CH₄ could be released to the atmosphere at rates exceeding 9 g of CH₄ m⁻² s⁻¹ from a trap in epigenetic permafrost disconnected from traditional geological sources over a period from a few hours to several days. The amount of methane released from a borehole exceeded the amount of the gas that was enclosed in large volumes of permafrost within a diameter up to 5 meters around the borehole. Such gas shows could be by mistake assumed as permanent gas seeps, which leads to the overestimation of the role of permafrost in global warming.

Cryosphere has a global role as a biogeophysical phenomenon. It affects the livelihoods of people inhabiting permafrost areas and is affected by human activity within and outside of the cryosphere’s geographical span. ‘Frozen commons’ (FCs) are cryosphere resources and landscapes, defined by snow, ice, and permafrost, that are experienced, used, protected and managed by groups of people together. This paper highlights collaboration between herders and scientists aimed at improving the understanding of FCs in northern Mongolia, a region of rapid cryosphere transformation. The impact of climate change on Indigenous and pastoralist communities in Mongolia is profound, leading to the damage or loss of FCs critical to local livelihoods. Therefore, Indigenous and local knowledge becomes crucial in assessing and predicting the climate-driven dynamics of FCs. In 2022, 2023, 2024 a team of permafrost scientists, geographers, and economists conducted interviews in reindeer and cattle herder camps in Khövsgöl Aimag (Province) located in the northern part of Mongolia. Local livelihoods do not depend only on cattle, which allows us to examine a variety of animal–environment interactions and impacts on pastoralism. The analysis of interviews indicates that FCs are a vital resource for the Khövsgöl communities and holds significant importance in their daily lives. Permafrost plays a key role for herders as it provides water resources for pastures and local rivers, which is critical during dry summers. Ice and snow also have many uses, such as a source of water, winter transport and the basis of cultural events. As winters become shorter and ice conditions become less predictable, the sustainability and availability of these resources for local people are under threat. In light of these challenges, it is imperative to formulate climate adaptation and mitigation strategies through collaborative efforts that actively involve and respect the perspectives of Indigenous and local people.