The functioning and vulnerability of permafrost are largely determined by near-surface ground ice content. However, high-quality, grid-based ground ice maps for the Northern Hemisphere are currently unavailable. This study presents the first 1-km resolution grid-based ground ice map within 5 m below the permafrost table across the Northern Hemisphere. The map integrates an unprecedented amount (1178 boreholes) of field measurement for volumetric ice content (VIC) and multisource geospatial data, especially paleoclimate, remote sensing data, and surficial geology units, using Copula-Embedded Bayesian Model Averaging (COP-BMA) techniques with multiple machine learning models and 200 ensemble simulations. The validation indicates relatively low errors (R2 = 0.86, RMSE = 7.08%VIC, bias = 0.02%VIC), while the uncertainty, represented by the 95% prediction interval (PI), is 16.08% ± 3.55%VIC. The map indicates that the total ice storage of near-surface permafrost across the Northern Hemisphere is approximately 54,600 km3 (47,800-62,300 km3), about twice the value from the International Permafrost Association map. This difference may be due to, but is not limited to, advancements in mapping techniques, the integration of additional measurement data, and improved spatial resolution. High VIC (>80%) is predominantly concentrated in low-lying plains, wetlands, and marshes. In contrast, mountainous regions, including the Qinghai-Xizang Plateau and Mongolian Plateau, exhibit lower VIC, typically ranging from 20% to 40%. The new ground ice map exhibits a spatial pattern that is largely consistent with previous maps while providing enhanced spatial detail. This high-resolution map serves as a benchmark for tracing permafrost changes and assessing impacts on climate, hydrology, ecosystems, and infrastructure in permafrost regions.

The Qinghai-Xizang Railway (QXR), a critical transportation corridor across the Qinghai-Xizang Plateau, is increasingly threatened by climate warming, primarily through permafrost thaw and active layer thickness variations. Reliable prediction of permafrost stability is therefore essential for assessing the long-term performance and safety of such infrastructure. In this study, we firstly analyze the climate prediction results of IPCC in 100a future and use the downscaling methods to get the atmospheric boundary conditions for the QXR. Then performed spatial distribution on borehole date along the Qinghai-Xizang Plateau engineering corridor (including QXR and Qinghai-Xizang Highway) in both the vertical and horizontal directions to obtain the twodimensional distribution of ground ice content and soil density. To address uncertainties associated with climate model biases and subgrid-scale topographic variability, Monte Carlo simulations were applied to produce probabilistic air-temperature datasets. Finally, using the Common Land Model (CoLM) with refined soil stratification specific to the QXR, the coupled hydrothermal processes of the ground surface and active layer were simulated, yielding spatially distributed soil surface temperatures along the corridor. The thawing index required by the Stefan equation was derived from near-surface soil temperatures, enabling prediction of the annual maximum seasonal thaw depth over the next 100 years. By integrating thaw depth with the spatial distributions of ground ice content and soil density, the maximum thaw settlement and corresponding confidence intervals were quantified. Based on settlement magnitude, the permafrost along the railway corridor was further classified into distinct stability categories. The results provide a probabilistic framework for long-term assessment of permafrost-related settlement risks and offer scientific support for adaptive design and maintenance strategies of the QXR under future climate change.

The timing and pattern of abrupt climatic events during the last glacial termination, particularly the Bølling-Allerød (B-A) Interstadial, are critical for understanding rapid climate transitions under global warming. Well-preserved glacial landforms on the Tibetan Plateau (TP) provide valuable insights into past climate change, yet glacier responses to the B-A Interstadial remain poorly constrained due to limited chronological data. Here, we report ten new 10Be surface exposure ages from glacially polished bedrock along the main ice-flow path in the Lahaku Valley, Haizishan Plateau (HZSP), southeastern TP. The results cluster tightly between 15.1±0.9 ka and 13.7±0.9 ka, with a mean of 14.3±0.5 ka, indicating a rapid deglaciation at the onset of the B-A Interstadial. These ages, combined with published 10Be ages in the HZSP, provide robust evidence for B-A deglaciation on the TP. Furthermore, this rapid deglaciation aligns with similar events observed across the Northern Hemisphere, pointing to a common hemispheric-scale climatic forcing. Comparative analysis of glacial and climatic records indicates that the primary driver was likely abrupt warming, linked to ocean-atmosphere processes associated with a reinvigorated Atlantic Meridional Overturning Circulation.

The new threat from atmospheric Micro/nano-plastics (MNPs) emissions now reaches far beyond the conventional scope of plastic-related issues. While MNP horizontal transport within the planetary boundary layer is well understood, limited knowledge of their vertical transport in the free troposphere and stratosphere hinder comprehensive modeling of their global atmospheric circulation. Considering that the production rates of radioactive beryllium isotopes (7Be and 10Be) above the tropopause is over 100 times higher than that in the near surface atmosphere, if relatively high concentrations and ratios of 10Be and 7Be can be observed near the surface, this phenomenon can serve as a unique isotope "fingerprint" for the invasion of deep stratospheric air invasion. Here, we present evidence of MNPs at mass concentrations of 0.0059-0.11 μg/m³ detected in Lhasa, southern Tibetan Plateau. And through synchronous high-precision observations of 7Be and 10Be, we have discovered strong stratospheric air signals during periods of high MNP concentration. Through the atmospheric transport models to delineate the occurrence, magnitude, retention period, flux, and characteristics of MNP pollution driven by upper-atmospheric vertical circulation in this high-elevation region. We found that under special topographic and aerodynamic conditions, atmospheric vertical circulation will promote the accumulation of MNPs for the enrichment and redistribution of MNPs. This work reveals the importance of vertical circulation in the upper atmosphere in the dynamics of MNP circulation based on evidence from beryllium isotopes.

Abstract Sustainable management of river basins requires an understanding of how water allocation responds to the human decisions driving it, along with the subsequent economic and ecological consequences. Current models often consider water allocation decisions as single and discontinuous events, overlooking the continuous and adaptive nature of human decision‐making processes. This limitation can lead to unintended economic and ecological consequences or even system collapse. We developed a socio‐hydrological model of water allocation that endogenizes the human decision‐making subsystem, which consists of Societal Value, Technology/Practice, and Government Regulation, and couples it with hydrological, economic, and ecological subsystems. Using a 70‐year data set (1949–2019) from the Heihe River Basin, we successfully reproduced the historical trajectory of water allocation. Our results reveal that while the economic subsystem (population and agricultural output) exhibited rapid, self‐propagating growth due to accumulation effects, the ecological subsystem (NPP of the natural vegetation and environmental flow) was characterized by significant hysteresis manifested as two distinct time lags: a delay in decision‐making recognition of ecosystem deterioration and delayed biophysical recovery following remedial interventions. These dual lags explain the transition phase (1990s–2000s) and the persistent trade‐off between economic expansion and ecological restoration. By formalizing the adaptive water allocation dynamics, our model provides a tool for anticipating response delays, thus more predictable water allocation strategies for sustainable basin management.

Abstract. The Tibetan Plateau, a pivotal component of the global climate system known as the "Asian Water Tower," governs freshwater availability for billions. However, the physical mechanisms linking stratospheric circulation to its precipitation variability remain poorly constrained, limiting predictive understanding. Here, this work constructs a new indicator based on the ratio of stratospheric tracer 10Be (t1/2 = 1.39 Ma) and 7Be (t1/2 = 53.29 d), to reveal the modulation mechanism of stratospheric Quasi-Biennial Oscillation (QBO) phase transitions on Tibetan Plateau precipitation processes and its possible large-scale vertical circulation associations. Analyzing synchronous wet-deposition data from Lhasa (Tibetan Plateau) and Xi'an (Loess Plateau) during the 2022–2023 QBO transition, we empirically analyzes the synchronous response relationship between isotope deposition and regional precipitation during the tropopause stable period determined by the 10Be/7Be ratio in precipitation samples. An XGBoost machine-learning model then isolates the coupled impact of the easterly QBO phase and upper-level circulation on precipitation. Our results demonstrate that during the observation period, the easterly QBO excites a meridional wind dipole, driving an anticyclonic circulation that enhances stratospheric air transport to the surface. This dynamical pathway substantially increases precipitation in the southern Tibetan Plateau by approximately 31 %. Attempting to mechanistically linking a fundamental mode of global atmospheric variability to regional water resources via stratospheric isotopic evidence, this framework advances the understanding of cross-scale interactions within the Earth system, with direct implications for evaluating climate model performance and future water security under global change.

Knowledge regarding former behavior of the East Antarctic Ice Sheet (EAIS) is crucial for assessing global sealevel change and understanding the global climate system. Yet, it remains challenging to examine pre-Last Glacial Maximum (LGM) glacial histories of the EAIS due to the limitations of the traditional geologic records. Recent studies suggest that blue ice areas (BIAs) and associated deposits (e.g. supraglacial moraines) have a potential to overcome this problem. However, the relationship between blue-ice evolution and climate changes is not yet well examined. In this study, we investigate two types of BIAs in the Grove Mountains, EAIS, on the basis of surface exposure dating of erratic boulders and cobbles on blue-ice moraines at Mount Harding and Escarpment. Here, we present 27 new ages, including single (10Be; n = 10) and paired (10Be and 26Al, n = 17) exposure-ages. The newly-obtained ages, along with previously-published 10Be data (n = 40), indicate that the studied BIAs have been relatively stagnant since the LGM, and that blue-ice moraines formed in a closed system are much older than those built in the absence of a barrier. Also, the compilation implies multiple phases of preLGM ice flow that corresponded to global cold periods. We suggest that there was likely a response of blue-ice evolution to Antarctic glaciations on orbital timescales.

High-energy cosmic rays bombard target atoms in near-surface minerals, initiating nuclear reactions that produce in situ cosmogenic nuclides such as 10Be and 26Al. Advances in cosmogenic nuclide techniques have been enabled by well-understood production mechanisms, highly sensitive detection at ultra-trace levels, and robust quantitative that describe nuclide production, accumulation, transport, and decay in the near-surface environment. These techniques have advanced Earth science by providing tools for surface exposure dating, sediment burial dating, and quantifying denudation rates of watersheds and bedrocks. This article presents a comprehensive review of the research history of terrestrial in situ cosmogenic nuclide production rates, the theoretical frameworks and computational methodologies used to construct production rate scaling models, with particular attention to key controlling factors, and evaluates the differences among various production rate scaling models and their underlying causes. To improve the accuracy and precision of future production rate scaling models, we recommend the following four research priorities: (1) Enhance quantitative comparison and data assimilation between measured and simulated cosmic-ray spectra to refine particle-transport simulation algorithms and reduce uncertainties in secondary cosmic-ray energy spectra. (2) Reconstruct temporal variations in geomagnetic field intensity and solar activity since the Pleistocene to provide more robust constraints on time-dependent cosmic-ray energy spectra. (3) Systematically measure and theoretically evaluate proton- and neutron-induced cross sections on main target atoms (O, Si, Al, Fe, Mg, etc.) across energy ranges relevant to TCN production and compile the results into a comprehensive evaluated database. (4) Strengthen geological calibrations of production rates across multi-nuclide (3He, 10Be, 14C, 21Ne, 26Al, 36Cl, etc.) and multi-mineral (quartz, calcite, etc.) systems to develop a globally applicable, internally consistent production rate model.

As important components of global commons, environmental changes in polar regions are crucial to the local and global sustainability. However, they have received little attention in the current framework of sustainable development goals (SDGs). This study examines the impacts of climate change in polar regions, emphasizing the interconnectedness of these areas with other parts of the global system. Here we show that polar regions are a limiting factor in achieving global SDGs, similar to the "shortest stave" in Liebig's barrel, primarily due to the teleconnection effects of climate tipping elements. Proactive actions should ensure polar regions aren't left behind in achieving global SDGs. We proposed a specific SDG target and five indicators for the interconnected effect of the cryosphere on climate actions and incorporate considerations for Indigenous peoples in polar regions. With the right actions and strengthened global partnerships, polar regions can be pivotal for advancing global sustainable development.

The effect of temperatures ranging from 0 K to 1000 K on the positron lifetime of He- or H-vacancy complexes in 3C-SiC are studied using first-principles calculations. We observed a steady decrease in the formation energy of H-vacancy complexes upon additional H introduction, in contrast to the variation tendency of formation energies seen in He-vacancy complexes. The intrinsic vacancies (VSi, VC, and VSi+C) exhibit different decrease in positron lifetime with the addition of He or H atoms, with the effect of He being more pronounced. Moreover, VC and its impurity-vacancy complexes are almost incapable of trapping delocalized positrons, with positron lifetimes close to those of the bulk. Positron lifetime calculations for the complexes show no significant temperature dependence from 0 K to 1000 K, except in the case of VC. The above results are interpreted by analysis of electron density, positron density, positron ground-state energy, and positron trapping energy analysis. The results provide a reference for future in-situ temperature-dependent positron lifetime experiments on impurity-vacancy complexes in 3C-SiC.

Geomorphic processes are shaped by climate changes, tectonic movements and human activities. Investigating these interactions is crucial for understanding climate change and landform dynamics. However, the mechanisms driving landform development in high-altitude regions such as the Tibetan Plateau (TP), largely unaffected by human or tectonic activities since the Holocene, remain unclear. This study investigated the Puruogangri icefield region on the central Tibetan Plateau (TP), where diverse landforms such as lakes, rivers, sand dunes and glaciers could offer valuable insights for geomorphic research. Using optically stimulated luminescence (OSL) dating, we analysed the Linggo Co delta and its outwash terraces. The results indicate that the lake maintained a higher water level from 6.2 to 3.5 ka, which dropped between 3.5 and 2.5 ka. The outwash terraces were formed during the periods of accelerated glacier melting around 5.0, 1.8 and 0.6 ka, with warm periods leading to the formation of delta foreset deposits and outwash terraces, while the cold periods characterised by reduced glacier meltwater resulted in the topset deposits as the lake levels decreased. These findings reveal that temperature could be the dominant factor influencing fluvial landform development in this region.

Rock glaciers, periglacial landforms with tongue- or lobe-shaped streams of slowly deforming frozen debris, play an important role in periglacial mountainous regions. The understanding of rock glaciers and their geoecological role at regional scales has been considerably hampered due to survey difficulties. We employ an automated approach for identifying rock glaciers and compile for the first time a complete rock glacier survey over the entire Tibetan Plateau. We find over 130,000 individual rock glaciers, much more than expected from previous inventories over any areas on Earth, also suggesting that the global number of rock glaciers is significantly underestimated today. We reveal an underestimated source of water storage to the Asian Water Tower and an enormous material flux due to rock glacier creep, which warrants consideration for its potential impact on downstreams. This result is also important for improving the modeling of mountain permafrost for a better anticipation of climate change impacts.

Qinghai-Tibet Plateau (QTP) is the largest permafrost region among middle- and low-latitude regions in the world. Permafrost in QTP is dominated by unstable and climate-driven. It is especially vulnerable to climate change and ecosystem disturbances (both natural and human). Currently, more than 9389 km of roads, 580 km of railways, 2631 km of power lines, and 1064590 m2 of buildings are located in the QTP permafrost area. Depending on altitude, the warming rate of the QTP has been twice the global average in recent decades and in the foreseeable future. Climate change-induced permafrost degradation can seriously threaten the stability of infrastructure and thus increase the infrastructure repair and replacement frequency. The consequence can be expressed as the shortening of useful life and increases maintenance costs, leading to diverse financial risks. The damage to infrastructure caused by near-surface permafrost degradation is directly related to the well-being of 10 million people and the sustainable development on the Qinghai-Tibet Plateau, the Third Pole of the Earth. Here we identify the economic damage caused by permafrost degradation to infrastructure on the Qinghai-Tibet Plateau by integrating data-driven projection, multihazard index, and lifespan replacement model. We found that additional cost of approximately $6.31 billion will be needed to maintain the service function of current infrastructure under the historical scenario (SSP245) by 2090. While 20.9% of these potential costs can be saved with strategic adaptations. Controlling global warming to below 1.5 °C will reduce the costs by $1.32 billion relative to the 2 °C target of Paris Agreement. These findings highlight the importance of mitigating global warming and of investment in the adaptation and maintenance of infrastructure on the Qinghai-Tibet Plateau, which has a sparse population but is a climate hotspot.

Abstract. The degradation of marginal permafrost is a sensitive indicator of climate change, with far-reaching implications on regional ecosystems, hydrology, and infrastructure. Located near the southern limit of latitudinal permafrost (SLLP) in Eastern Asia, Northeast China has experienced pronounced permafrost retreat and persistent ground warming in recent decades. This study develops a physics-informed machine learning (PIML) framework that integrates the Temperature at the Top of Permafrost (TTOP) model, observed changes in land use and land cover (LULC), and climate projections from the Coupled Model Intercomparison Project 6 (CMIP6) to improve the understanding and prediction of permafrost dynamics in the region. Results indicate that, under the SSP5-8.5 scenario, permafrost extent may decline by more than 90 % by the end of the 21st century, primarily driven by a sharp reduction in the air freezing index (AFI), especially in high-latitude and high-elevation zones. Land use and cover changes (LUCC), particularly urban expansion and deforestation, further exacerbate ground thermal disturbances. Spatially, mountainous forested areas, such as the Da Xing’anling Mountains, exhibit relatively greater resilience to warming due to dense vegetation and complex topography that help buffer surface energy fluxes. Feature attribution analysis identifies surface temperature, snow cover duration, and vegetation as dominant drivers of permafrost stability, while Uniform Manifold Approximation and Projection (UMAP) clustering reveals distinct degradation trajectories across different land cover types. This study highlights the complex interplay of climatic and anthropogenic factors in permafrost evolution and demonstrates the utility of integrating physical modelling with machine learning to support ecological conservation and infrastructure risk management in cold regions environment.

ABSTRACTPermafrost degradation varies spatially; however, the underlying mechanism remains partially unclear. In this study, we predicted permafrost variation under the influence of climate change to investigate the sensitivity of permafrost degradation to geological and climatic conditions. The results revealed that geological strata can strongly impact the permafrost degradation process. Mainly due to the greater thermal conductivity of sandy gravel in the Arctic, the complete thaw of permafrost will be greatly delayed by more than 160 years compared with that on the Qinghai–Tibet Plateau (QTP). Climatic conditions, such as snow depth, can also greatly affect the degradation process of permafrost: The thaw of permafrost will be delayed by more than 140 years when the snow depth decreases from 0.7 to 0.1 m. Peat soil thickness at ground surface can also affect permafrost degradation. The permafrost temperature increases as peat soil thickens when the thickness is less than 1.0 m, whereas there is a critical peat soil thickness (approximately 0.2 and 0.5 m on the QTP and in the Arctic, respectively) under which permafrost will thaw at the fastest rate. The findings highlight the influence of geology and climate over permafrost degradation.