Alpine wet meadow (AWM), an important wetland type on the Qinghai-Tibet Plateau (QTP), is sensitive to climate change, which alters the soil hydrothermal regime and impacts ecological and hydrological functions in permafrost regions. The mechanisms underlying extreme AWM degradation in the QTP and hydrothermal factors controlling permafrost degradation remain unclear. In this study, soil hydrothermal processes, soil heat migration, and the permafrost state were measured in AWM and extremely degraded AWM (EDAWM). The results showed that the EDAWM exhibited delayed onset of both soil thawing and freezing, shortened thawing period, and extended freezing period at the lower boundary of the active layer. The lower ground temperatures resulted in a 0.2 m shallower active layer thickness in the EDAWM compared with the AWM. Moreover, the EDAWM altered soil thermal dynamics by redistributing energy, modifying soil moisture, preserving soil organic matter, and adjusting soil thermal properties. As for energy budget, a substantial amount of heat in the EDAWM was consumed by turbulent heat fluxes, particularly latent heat flux, which reduced the amount of heat transferred to the ground. Additionally, the higher soil organic matter content in EDAWM decreased the annual mean soil thermal conductivity from 1.42 W m- 1 K-1 in AWM to 1.26 W m- 1 K-1 in EDAWM, slowing down heat transfer within the active layer and consequently mitigating permafrost degradation. However, with continued climate warming, the soil organic matter content in EDAWM will inevitably decline due to microbial decomposition in the absence of new organic inputs. As the soil organic matter content diminishes, soil heat transfer processes will likely accelerate, and the permafrost warming rate may surpass that in undistributed AWM. These findings enhance our understanding of how alpine ecosystem succession influences regional hydrological cycles and greenhouse gas emissions.

Subarctic palsa mires are natural indicators of the status of permafrost in its sporadic distribution zone. Estimation of the rate of their thawing can become an auxiliary indicator to predict climate shifts. The formation, growth, and degradation of palsas are dynamic processes that depend on seasonal weather fluctuations and local environmental factors. Therefore, accurate forecasts of palsas conditions and related ecosystem shifts must be based on a broad set of attributes of palsas from different regions of the Northern Hemisphere. With this in mind, we studied two palsa mires sites on the Kola Peninsula, for which no thorough descriptions were previously available. The first site, Chavanga, is at the southern limit of the permafrost zone under unfavorable climatic conditions and is a collapsing relic. The second site, Ponoy, in contrast, is within the sporadic permafrost zone with relatively cold and dry conditions. Our dataset was created by combining several methods to produce detailed spatial models of permafrost for the studied palsa mires. We used 3D ground-penetrating radar (GPR) survey, UAV-based orthophoto maps, peat thermometry, time-domain reflectometry, and manual sampling. We developed two integrated geospatial models that describe the active layer, the configuration of the palsa frozen core, and its thermal state and identify the zones of the most intense thawing. These observations revealed a significant thermal effect of the groundwater flow and its critical role in the palsas segmentation and rapid collapse. We have investigated a regulating effect of micromorphological features of palsa mounds such as heights, slope, depressions, and mire mineral bed through groundwater drainage. As a result, two new scenarios for the palsa degradation process have been developed, emphasizing the influence of environmental factors on the permafrost condition.

Numerous endorheic lakes in the Qinghai-Tibet Plateau (QTP) have shown a dramatic increase in total area since 1996. These expanding lakes are mainly located in the interior regions of the QTP, where permafrost is widely distributed. Despite significant permafrost degradation due to global warming, the impact of permafrost thawing on lake evolution in QTP has been underexplored. This study investigated the permafrost degradation and its correlation with lake area increase by selecting four lake basins (Selin Co, Nam Co, Zhari Namco, and Dangqiong Co) in QTP for analysis. Fluid-heat-ice coupled numerical models were conducted on the aquifer cross-sections in these four lake basins, to simulate permafrost thawing driven by rising surface temperatures, and calculate the subsequent changes in groundwater discharge into the lakes. The contribution of these changes to lake storage, which is proportional to lake area, was investigated. Numerical simulation indicates that from 1982 to 2011, permafrost degradation remained consistent across the four basins. During this period, the active layer thickness first increased, then decreased, and partially transformed into talik, with depths reaching up to 25 m. By 2011, groundwater discharge had significantly risen, exceeding 2.9 times the initial discharge in 1988 across all basins. This increased discharge now constitutes up to 17.67 % of the total lake water inflow (Selin Co). The dynamic lake water budget further suggests that groundwater contributed significantly to lake area expansion, particularly since 2000. These findings highlight the importance of considering permafrost thawing as a crucial factor in understanding the dynamics of lake systems in the QTP in the context of climate change.

Vulnerability of peat plateaus to global warming was analyzed in northeastern European Russia. A laboratory experiment on artificial incubation of peat was carried out to analyze the resilience of organic matter of frozen peat bogs (palsas) to decomposition. The rate of mineralization of peat organic matter was calculated from data on the CO2 and CH4 emissions from the peat incubated at a temperature of +4 degrees C under artificial aerobic and anaerobic conditions during 1300 days. Peat samples were taken from the active layer (AL), transitional layer (TL), and permafrost layer (PL). The delta 13C and delta 15N isotopes and the C/N, O/C, and H/C ratios were determined as indicators of change in the decomposition rate of organic matter. By the 1300th day of the experiment under aerobic conditions, the total CO2 amount released from the analyzed samples (per 1 g of carbon) was 10.24-37.4 mg C g-1 (on average, 25.76 mg C g-1), while under anaerobic conditions, it was only 2.1-3.38 mg C g-1 (on average, 3.15 mg C g-1). The CH4 emission was detected only in the peat from the transitional layer in very small quantities. The incubation experiment results support the hypothesis that peat plateaus are resilient, especially under anaerobic conditions, regardless the ongoing climate warming.

Soil microorganisms play a pivotal role in the biogeochemical cycles of alpine meadow ecosystems, especially in the context of permafrost thaw. However, the mechanisms driving microbial community responses to environmental changes, such as variations in active layer thickness (ALT) of permafrost, remain poorly understood. This study utilized next-generation sequencing to explore the composition and co-occur rence patterns of soil microbial communities, focusing on bacteria and micro-eukaryotes along a permafrost thaw gradient. The results showed a decline in bacterial alpha diversity with increasing permafrost thaw, whereas micro-eukaryotic diversity exhibi ted an opposite trend. Although changes in microbial community composition were observed in permafrost and seasonally frozen soils, these shifts were not statistically significant. Bacterial communities exhibited a greater differentiation between frozen and seasonally frozen soils, a pattern not mirrored in eukaryotic communities. Linear discriminant analysis effect size analysis revealed a higher number of potential biomark ers in bacterial communities compared with micro-eukaryotes. Bacterial co-occurrence networks were more complex, with more nodes, edges, and positive linkages than those of micro-eukaryotes. Key factors such as soil texture, ALT, and bulk density significantly influenced bacterial community structures, particularly affecting the relative abundan ces of the Acidobacteria, Proteobacteria, and Actinobacteria phyla. In contrast, fungal communities (e.g., Nucletmycea, Rhizaria, Chloroplastida, and Discosea groups) were more affected by electrical conductivity, vegetation coverage, and ALT. This study highlights the distinct responses of soil bacteria and micro-eukaryotes to permafrost thaw, offering insights into microbial community stability under global climate change.

We present an innovative approach to understanding permafrost degradation processes through the application of new environment-based particle image velocimetry (E-PIV) to time-lapse imagery and correlation with synchronous temperature and rainfall measurements. Our new approach to extracting quantitative vector movement from dynamic environmental conditions that can change both the position and the color balance of each image has optimized the trade-off between noise reduction and preserving the authenticity of movement data. Despite the dynamic polar environments and continuous landscape movements, the E-PIV provides the first quantitative real-time associations between environmental drivers and the responses of permafrost degradation mechanism. We analyze four event-based datasets from an island southwest of Tuktoyaktuk, named locally as Imnaqpaaluk or Peninsula Point near Tuktoyaktuk, NWT, Canada, spanning a 5-year period from 2017 to 2022. The 2017 dataset focuses on the interaction during a hot dry summer between slope movement and temperature changes, laying the foundation for subsequent analyses. In 2018, two datasets significantly expand our understanding of typical failure mechanisms in permafrost slopes: one investigates the relationship between slope movement and rainfall, while the other captures an overhang collapse, providing a rare quantitative observation of an acute landscape change event. The 2022 dataset revisits the combination of potential rain and air temperature-related forcing to explore the environment-slope response relationship around an ice wedge, a common feature of ice-rich permafrost coasts. These analyses reveal both a direct but muted association with air temperatures and a detectable delayed slope response to the occurrence of rainfall, potentially reflective of the time taken for the warm rainwater to infiltrate through the active layer and affect the frozen ground. Whilst these findings also indicate that other factors are likely to influence permafrost degradation processes, the associations have significant implications given the projections for a warmer, wetter Arctic. The ability to directly measure permafrost slope responses offers exciting new potential to quantitatively assess the sensitivity of different processes of degradation for the first time, improving the vulnerability components of hazard risk assessments, guiding mitigation efforts, and better constraining future projections of erosion rates and the mobilization of carbon-rich material.

In permafrost regions, vegetation growth is influenced by both climate conditions and the effects of permafrost degradation. Climate factors affect multiple aspects of the environment, while permafrost degradation has a significant impact on soil moisture and nutrient availability, both of which are crucial for ecosystem health and vegetation growth. However, the quantitative analysis of climate and permafrost remains largely unknown, hindering our ability to predict future vegetation changes in permafrost regions. Here, we used statistical methods to analyze the NDVI change in the permafrost region from 1982 to 2022. We employed correlation analysis, multiple regression residual analysis and partial least squares structural equation modeling (PLS-SEM) methods to examine the impacts of different environmental factors on NDVI changes. The results show that the average NDVI in the study area from 1982 to 2022 is 0.39, with NDVI values in 80% of the area remaining stable or exhibiting an increasing trend. NDVI had the highest correlation with air temperature, averaging 0.32, with active layer thickness coming in second at 0.25. Climate change plays a dominant role in NDVI variations, with a relative contribution rate of 89.6%. The changes in NDVI are positively influenced by air temperature, with correlation coefficients of 0.92. Although the active layer thickness accounted for only 7% of the NDVI changes, its influence demonstrated an increasing trend from 1982 to 2022. Overall, our results suggest that temperature is the primary factor influencing NDVI variations in this region.

Thermokarst landslide (TL) activity in the Qinghai-Tibet Plateau (QTP) is intensifying due to climate warminginduced permafrost degradation. However, the mechanisms driving landslide formation and evolution remain poorly understood. This study investigates the spatial distribution, annual frequency, and monthly dynamics of TLs along the Qinghai-Tibet engineering corridor (QTEC), in conjunction with in-situ temperature and rainfall observations, to elucidate the interplay between warming, permafrost degradation, and landslide activity. Through the analysis of high-resolution satellite imagery and field surveys, we identified 1298 landslides along the QTEC between 2016 and 2022, with an additional 386 landslides recorded in a typical landslide-prone subarea. In 2016, 621 new active-layer detachments (ALDs) were identified, 1.3 times the total historical record. This surge aligned with unprecedented mean annual and August temperatures. The ALDs emerged primarily between late August and early September, coinciding with maximum thaw depth. From 2016 to 2022, 97.8 % of these ALDs evolved into retrogressive thaw slumps (RTSs), identified as active landslides. Landslides typically occur in alpine meadows at moderate altitudes and on gentle northward slopes. The thick ice layer near the permafrost table serves as the material basis for ALD occurrence. Abnormally high temperature significantly increased the active layer thickness (ALT), resulting in melting of the ice layer and formation of a thawed interlayer, which was the direct causing factor for ALD. By altering the local material, micro-topography, and thermal conditions, ALD activity significantly increases RTS susceptibility. Understanding the mechanisms of ALD formation and evolution into RTS provides a theoretical foundation for infrastructure development and disaster mitigation in extreme environments.

Substantial degradation can occur to warm permafrost due to changes in surface conditions resulting from infrastructure development and climate warming. The associated geohazards, including differential settlement, slope instability, and liquefaction of degraded, unconsolidated materials in seismically active warm permafrost regions, pose substantial threats to the built infrastructure. Among them, seismic hazards of degraded permafrost have received little attention. This paper aims to provide a case study of an airport built on warm permafrost about 80 years ago, focusing on climate changes, permafrost degradation, and observed seismic hazards during a strong earthquake. The study site, that is, the Northway Airport, is located in a discontinuous permafrost area in Interior Alaska. Geotechnical data from 1973, 1991, and 2005 were compiled and analyzed to reveal permafrost degradation at various surface conditions, and are compared with the well-known degradation data from a site in Fairbanks. Furthermore, the responses of the airport runway during the 2002 Denali earthquake (Mw = 7.9), including liquefaction and lateral spreading displacements, are described and analyzed. And the seismic hazards of civilian airports built on permafrost across Alaska are surveyed. Distinct trends are revealed in two periods, namely, from 1943 to 1975 and from 1976 to 2021, for air temperature, precipitation, and wind speed. Permafrost tables were observed to drop with time at various rates for different surface conditions. Liquefaction and lateral spreading were observed extensively during the earthquake. The locations of observed liquefaction at the airport are mapped, and the lateral spreading displacements are estimated based on available photos. The standard penetration test data collected during geotechnical investigations are analyzed, and a liquefiable layer is identified at the talik between the active layer and the permafrost table. Moreover, 55% of Alaska's civilian airports are in permafrost areas. Among them, two-thirds fall within seismic zones with a risk level of 3 or above. This study demonstrates the high seismic risks of degraded permafrost and its potential impact on the built infrastructure.

The degradation of permafrost in the Northern Hemisphere is expected to persist and potentially worsen as the climate continues to warm. Thawing permafrost results in the decomposition of organic matter frozen in the ground, which stores large amounts of soil organic carbon (SOC), leading to carbon being emitted into the atmosphere in the form of carbon dioxide and methane. This process could potentially contribute to positive feedback between global climate change and permafrost carbon emissions. Accurate projections of permafrost thawing are key to improving our estimates of the global carbon budget and future climate change. Using data from the latest generation of climate models (CMIP6), this paper explores the challenges involved in assessing the annual active layer thickness (ALT), defined as the maximum annual thaw depth of permafrost, and estimated carbon released under various Shared Socioeconomic Pathway (SSP) scenarios (SSP1-2.6, SSP2-4.5, SSP3-7.0 and SSP5-8.5). We find that the ALT estimates derived from CMIP6 model soil temperatures show significant deviations from the observed ALT values. This could lead to inconsistent estimates of carbon release under climate change. We propose a simplified approach to improve the estimate of the changes in ALT under future climate projections. These predicted ALT changes, combined with present-day observations, are used to estimate vulnerable carbon under future climate projections. CMIP6 models project ALT changes of 0.1-0.3 m per degree rise in local temperature, resulting in an average deepening of approx. 1.2-2.1 m in the northern high latitudes under different scenarios. With increasing temperatures, permafrost thawing starts in Southern Siberia, Northern Canada, and Alaska, progressively extending towards the North Pole by the end of the century under high emissions scenarios (SSP5-8.5). Using projections of ALT changes and vertically resolved SOC data, we estimate the ensemble mean of decomposable carbon stocks in thawed permafrost to be approximately 115 GtC (gigatons of carbon in the form of CO2 and CH4) under SSP1-2.6, 180 GtC under SSP2-4.5, 260 GtC under SSP3-7.0, and 300 GtC under SSP5-8.5 by the end of the century.