The thermal coupling between the atmosphere and the subsurface on the Qinghai-Tibetan Plateau (QTP) governs permafrost stability, surface energy balance, and ecosystem processes, yet its spatiotemporal dynamics under accelerated warming are poorly understood. This study quantifies soil-atmosphere thermal coupling ((3) at the critical 0.1 m root-zone depth using in-situ data from 99 sites (1980-2020) and a machine learning framework. Results show significantly weaker coupling in permafrost (PF) zones (mean (3 = 0.42) than in seasonal frost (SF) zones (mean (3 = 0.50), confirming the powerful thermal buffering of permafrost. Critically, we find a widespread trend of weakening coupling (decreasing (3) at 66.7 % of sites, a phenomenon most pronounced in SF zones. Our driver analysis reveals that the spatial patterns of (3 are primarily controlled by surface insulation from summer rainfall and soil moisture. The temporal trends, however, are driven by a complex and counter-intuitive interplay. Paradoxically, rapid atmospheric warming is the strongest driver of a strengthening of coupling, likely due to the loss of insulative snow cover, while trends toward wetter conditions drive a weakening of coupling by enhancing surface insulation. Spatially explicit maps derived from our models pinpoint hotspots of accelerated decoupling in the eastern and southern QTP, while also identifying high-elevation PF regions where coupling is strengthening, signaling a loss of protective insulation and increased vulnerability to degradation. These findings highlight a dynamic and non-uniform response of land-atmosphere interactions to climate change, with profound implications for the QTP's cryosphere, hydrology, and ecosystems.

This study presents the first high-resolution Regional Climate Model 5 (RegCM5) analysis of the unprecedented May-June 2024 heatwave in India, evaluating the role of absorbing aerosols-black carbon (BC) and dust-in amplifying extreme heat. Heatwaves have a severe impact on health, mortality, and agriculture, with absorbing aerosols exacerbating warming. MERRA-2 Aerosol Optical Depth (AOD) anomalies show that BC peaked at +0.027 in May, weakening in June, while dust remained higher (up to +0.36), intensifying over the Indo-Gangetic Plain (IGP) and northwestern India. RegCM5 simulations, validated against India Meteorological Department (IMD) observational data, indicate that these aerosols amplified surface temperature anomalies, with BC-induced warming exceeding +4 degrees C in northern India during May, while dust produced stronger anomalies, surpassing +5 degrees C in the IGP and Rajasthan in June. BC-induced warming was vertically distributed and more pronounced under clear skies, whereas dust-induced warming was surface-concentrated and persisted longer in regions with higher dust concentrations. Both aerosols increased net shortwave radiation (SWR; >300 W m(-2) for BC, similar to 270 W m(-2) for dust) and upward longwave radiation (ULR; >130 W m(-2)), inducing surface energy imbalances. This radiative forcing caused lower-tropospheric warming (up to +3 degrees C at 925 hPa for BC and 850 hPa for dust) and humidity deficits (-0.009 kg/kg), which stabilised the atmosphere, suppressed convection, and delayed monsoon onset. These findings highlight aerosol-radiation interactions as critical drivers of heatwave onset and persistence, emphasizing the need for their integration into regional climate models and early warning systems.

Infrastructure in northern regions is increasingly threatened by climate change, mainly due to permafrost thaw. Prediction of permafrost stability is essential for assessing the long-term stability of such infrastructure. A key aspect of geotechnical problems subject to climate change is addressing the surface energy balance (SEB). In this study, we evaluated three methodologies for applying surface boundary conditions in longterm thermal geotechnical analyses, including SEB heat flux, n-factors, and machine learning (ML) models by using ERA5-Land climate reanalysis data until 2100. We aimed to determine the most effective approach for accurately predicting ground surface temperatures for climate-resilient design of northern infrastructure. The evaluation results indicated that the ML-based approach outperformed both the SEB heat flux and n-factors methods, demonstrating significantly lower prediction errors. The feasibility of long-term thermal analysis of geotechnical problems using ML-predicted ground surface temperatures was then demonstrated through a permafrost case study in the community of Salluit in northern Canada, for which the thickness of the active layer and talik were calculated under moderate and extreme climate scenarios by the end of the 21st century. Finally, we discussed the application and limitations of surface boundary condition methodologies, such as the limited applicability of the n-factors in long-term analysis and the sensitivity of the SEB heat flux to inputs and thermal imbalance. The findings highlight the importance of selecting suitable boundary condition methodologies in enhancing the reliability of thermal geotechnical analyses in cold regions.

Widespread dieback of natural Mongolian pine (Pinus sylvestris var. mongolica) forests in Hulunbuir sandy land since 2018 has raised concerns about their sustainability in afforestation programs. We hypothesized that this dieback is driven by two interrelated mechanisms: (1) anthropogenic fire suppression disrupting natural fire regime, and (2) climate change-induced winter warming reducing snow cover duration and depth. To test these, we quantified dieback using Green Normalized Difference Vegetation Index (GNDVI) across stands with varying fire histories via UAV-based multispectral imagery, alongside long-term climatic observations (1960-2024) of temperature, precipitation, and snow dynamics from meteorological stations combined with remote sensing datasets. Results showed that an abrupt change point in 2018 for both annual precipitation and mean temperature was identified, coinciding with dieback. Significant negative linear relationship between GNDVI (forest health) and last fire interval indicated prolonged fire exclusion exacerbating dieback, possibly via pathogen/pest accumulation. Winter temperature rose significantly during 1960-2023, with notable acceleration following abrupt change point in 1987. Concurrently, winters during 2018-2023 exhibited pronounced warming, with snow cover duration reduced by 23 days and snow depth diminished by 7.6 cm. These conditions reduced snowmelt -derived soil moisture (critical water source) recharge in early spring, exacerbating drought stress during critical growth periods and predisposing trees to pest and disease infestations. Our results support both hypotheses, demonstrating that dieback is synergistically driven by fire regime alteration and climate-mediated snowpack reductions. Converting pure pine forests into mixed pine-broadleaf forests via differentiated water sources was proposed to restore ecological resilience in sandy ecosystems.

The Three-Rivers Headwater Region (TRHR) is located on the Tibetan Plateau, within a transitional zone between seasonally frozen ground and continuous permafrost. Over 70 % of the region is predominantly covered by alpine grasslands, a vulnerable ecosystem increasingly threatened by ongoing permafrost degradation. This study utilized satellite data to analyze permafrost degradation by measuring active layer thickness (ALT) and the soil non-frozen period (NFP), and to investigate their impacts on alpine grassland growth. Results showed significant permafrost degradation from 2000 to 2020, with ALT thickening at a rate of 7.79 cm/decade (p < 0.05) and NFP lengthening by 1.1 days/yr (p < 0.05). Simultaneously, grassland vegetation exhibited a significant greening trend (0.0014 yr(-1), p < 0.01). Using the partial least squares (PLS) regression method, the study evaluated the relationships between grassland dynamics and permafrost degradation, while jointly accounting for climate variables (temperature, precipitation, and sunshine duration). ALT thickening was the dominant explanatory variable for grassland growth in 11.09 % of the region, and it was positively correlated in relatively cold western and alpine areas, but negatively correlated in the relatively warm eastern and central regions. NFP extension was the dominant explanatory variable for grassland growth in 10.38 % of the region, although its positive correlation weakened as climate conditions transitioned from relatively cold-dry to relatively warm-wet. Although permafrost degradation was positively correlated with grassland greening in relatively cold regions, the diminishing benefit of NFP extension and the adverse effects of ALT thickening may increasingly undermine grassland stability in relatively warm regions under further climate warming.

In light of a series of recent fatal landslides in Alaska, we set out to determine 1) the history of Alaskan landslides and 2) if the number of associated fatalities has increased with time. To answer our research questions, we searched a combination of 24 digital newspapers and online media sources, including historic digitized Alaskan newspapers, seeking landslides that affected people and/or infrastructure. This resulted in an inventory of 281 landslides occurring in Alaska since 1883. Our database includes the date on which the landslide occurred, its location and probable trigger, any reported injuries and/or fatalities, other reported damage, and the media source. Our inventory indicates that the number of reported landslides started to increase in the 1980's, and has increased dramatically in recent decades. We correlate the increase in landslides to a 1.2 degrees C to 3.4 degrees C increase in average annual air temperature and a 3% to 27% increase in precipitation over the last 50 years across Alaska. This change in climate is degrading permafrost, increasing the number of annual freeze/thaw events, and contributing to larger and more intense precipitation events - such as atmospheric rivers, all of which increase landslide susceptibility in various parts of the state. Alaska's last four fatal landslides occurred in Southeast Alaska, which has experienced the greatest increase in the number of landslides per capita. Our landslide database can serve as the initial inventory for analyses of landslides related to specific extreme weather events, as well as a resource to determine costs incurred from landslide-related damage.

Studying permafrost changes under different (e.g., glacial/interglacial) and changing (e.g., current various scenarios) climates can potentially advance our understanding of permafrost's responses to climate change and further enable informed policy making for mitigating impacts from permafrost changes. Despite existing studies generally focusing on permafrost change during certain periods, here, we have synthetically examined the changes of the Northern Hemisphere near-surface permafrost during the six periods (Last Glacial Maximum (LGM, similar to 21 ka), mid-Holocene (MH, similar to 6 ka), preindustrial (PI, ca 1850), future 1.5 degrees C and 2.0 degrees C global warming periods, and end of the 21st century), using the surface frost index (SFI) model and outputs of six climate models. Simulated climate anomalies plus present-day observed climatology are used to drive the SFI model in this study. This helps correct systematic biases in permafrost change simulations.The results show that multi-model ensemble extent of present-day near-surface permafrost in the Northern Hemisphere agree well with the observations, with an area bias of 0.27x106 km2 in area (1.8% of the total observed area). Minor deviations (1.55x106 km2) in the simulated present-day permafrost extents across the climate models indicate a low inter-model diversity. In response to changes in annual mean surface air temperature of -10.3 +/- 2.3 degrees C (LGM), +0.1 +/- 0.5 degrees C (MH), +2.6 +/- 0.7 degrees C (1.5 degrees C global warming, RCP4.5), +3.6 +/- 1.0 degrees C (2.0 degrees C global warming, RCP4.5), and +5.0 +/- 1.3 degrees C (end of the 21st century, RCP4.5) in present-day permafrost regions relative to the PI, the changes in near-surface permafrost area are +33%+/- 30% (LGM), -13%+/- 6% (MH), -25%+/- 8% (1.5 degrees C warming, RCP4.5), -35% +/- 10% (2.0 degrees C warming, RCP4.5), and -55%+/- 12% (end of the 21st century, RCP4.5), respectively. From the LGM to the future, near-surface permafrost extent substantially decreases, underlining its high sensitivity to climate change and implying its potentially profound impacts in a warming future.

Understanding the relationship between soil moisture and vegetation is crucial for future projections of ecosystem and water resources. While their hysteresis loop relationship, which arises from their asynchrony in intra-annual variation, remains underexplored. This study used the hysteresis loop type and area (Ah) to characterize the relationship between root zone soil moisture (RZSM) and normalized difference vegetation index (NDVI) across China from 1986 to 2015, and examined its ecological implications. The results identified four types of hysteresis loops. The clockwise loop, with a delayed single peak of RZSM relative to NDVI, was primarily found in north China and the Qinghai-Tibet Plateau, indicating severe water limitation during early growth period. The counterclockwise loop, with an advanced single peak of RZSM relative to NDVI, was common in southeast China's forest, suggesting a shift towards energy limitation. The 8-shaped loop, resulting from double peaks in either RZSM or NDVI due to climate change (e.g., snowmelt) and human disturbance (e.g., irrigation and crop harvest), was observed in northwest China's glaciers and croplands in south and northeast China. The multicrossed loop, marked by multimodal intra-annual variations in both RZSM and NDVI, was predominantly found in northwest China's barren lands. Additionally, from 1986 to 2015, this study observed a shift from 8-shaped or multi-crossed loops to clockwise or counterclockwise loops in some regions like the Yellow River Basin, implying a trend of revegetation. Furthermore, a higher Ah generally indicated more severe water limitation or greater mismatch between RZSM and NDVI. Significant changes in Ah, such as increases in the Yellow River Basin, suggested intensified water limitations, while decreases in southeast and northwest China pointed to an earlier peak of the growing and rainy seasons. This study provides insights into the dynamic interactions between soil moisture and vegetation, offering valuable guidance for ecological management across diverse ecosystems.

Permafrost in the Qinghai-Tibet Plateau (QTP) is highly sensitive to climate change, but its evolution over past century remains unclear. Based on the QTP climate change analysis since the 20th century, our study employed machine learning technique with field observations to construct permafrost simulation models, clarify its evolution processes, and reveal its changes on vertical zonation and sunny-shady slope distribution under climate warming. The results indicated that the QTP air temperature trends included initial warming (1900-1940 s, 0.13 degrees C/10a), cooling (1950-1960 s, - 0.20 degrees C/10a), and warming again (1970s to 2010s, 0.21 degrees C/10a). Precipitation patterns showed a slight decrease (- 0.33 mm/10a), rapid decrease (- 6.75 mm/10a), and gradual increase (6.57 mm/10a). Correspondingly, significant permafrost changes were recorded during the periods of 1900s, 1940s, 1960s, and 2010s, with the permafrost areas of 1.28, 1.19, 1.30, and 1.10 x 106 km2, respectively, and average mean annual ground temperature (active layer thickness) were - 2.82 +/- 1.93 degrees C (1.89 +/- 0.72 m), - 2.58 +/- 1.91 degrees C (2.21 +/- 0.78 m), - 2.86 +/- 1.94 degrees C (2.10 +/- 0.79 m), and - 2.26 +/- 1.72 degrees C (2.23 +/- 0.75 m) (mean +/- standard deviation), respectively. The southern Qiangtang Plateau and Three Rivers Source region exhibited significant permafrost changes during both the warming and cooling stages. Climate warming over the past 50 years has raised the average permafrost distribution altitude by 43 m, and accelerated its degradation on sunny slopes. These findings exhibit new knowledges on the QTP permafrost evolution and provide scientific references for permafrost degradation research under climate warming.

Emerging contaminants and climate change are major challenges that soil organisms are facing today. Triclosan (TCS), an antibacterial agent, is widespread and hazardous in terrestrial environments, but there is a lack of information on how its toxicity will change because of climate change. The aim of the study was to evaluate the short-term effects of increased temperature, decreased soil moisture content (drought), and their complex interaction on triclosan-induced biochemical changes in Eisenia fetida (as well as growth and survival). Four different treatments were used in TCS-contaminated soil tests with E. fetida (10-750 mg TCS kg-1): C (21 degrees C + 60 % water holding capacity (WHC)), D (21 degrees C and 30 % WHC), T (25 degrees C + 60 % WHC), and T + D (25 degrees C + 30 % WHC). The more prominent TCS effect on the survival was seen only after two weeks and at the high TCS concentrations, though a negative effect on weight growth was recorded after one week of exposure at all tested TCS concentrations and climate conditions. Under standard (C) conditions, an activated E. fetida antioxidative system effectively reduced the oxidative stress induced by TCS. Changes in the climatic conditions influenced E. fetid a's biochemical response to TCS-induced oxidative stress. Despite the enhanced activity of antioxidant enzymes, the combination of drought (D) and TCS caused significant lipid peroxidation in E. fetida. Under elevated temperature, E. fetida experienced oxidative stress and a considerable rise in lipid peroxidation due to insufficient activation or inhibition of antioxidant enzymes.