Over the past decades, the cryosphere has changed significantly in High Mountain Asia (HMA), leading to multiple natural hazards such as rock-ice avalanches, glacier collapse, debris flows, landslides, and glacial lake outburst floods (GLOFs). Monitoring cryosphere change and evaluating its hydrological effects are essential for studying climate change, the hydrological cycle, water resource management, and natural disaster mitigation and prevention. However, knowledge gaps, data uncertainties, and other substantial challenges limit comprehensive research in climate-cryosphere-hydrology-hazard systems. To address this, we provide an up-to-date, comprehensive, multidisciplinary review of remote sensing techniques in cryosphere studies, demonstrating primary methodologies for delineating glaciers and measuring geodetic glacier mass balance change, glacier thickness, glacier motion or ice velocity, snow extent and water equivalent, frozen ground or frozen soil, lake ice, and glacier-related hazards. The principal results and data achievements are summarized, including URL links for available products and related data platforms. We then describe the main challenges for cryosphere monitoring using satellite-based datasets. Among these challenges, the most significant limitations in accurate data inversion from remotely sensed data are attributed to the high uncertainties and inconsistent estimations due to rough terrain, the various techniques employed, data variability across the same regions (e.g., glacier mass balance change, snow depth retrieval, and the active layer thickness of frozen ground), and poor-quality optical images due to cloudy weather. The paucity of ground observations and validations with few long-term, continuous datasets also limits the utilization of satellite-based cryosphere studies and large-scale hydrological models. Lastly, we address potential breakthroughs in future studies, i.e., (1) outlining debris-covered glacier margins explicitly involving glacier areas in rough mountain shadows, (2) developing highly accurate snow depth retrieval methods by establishing a microwave emission model of snowpack in mountainous regions, (3) advancing techniques for subsurface complex freeze-thaw process observations from space, (4) filling knowledge gaps on scattering mechanisms varying with surface features (e.g., lake ice thickness and varying snow features on lake ice), and (5) improving and cross-verifying the data retrieval accuracy by combining different remote sensing techniques and physical models using machine learning methods and assimilation of multiple high-temporal-resolution datasets from multiple platforms. This comprehensive, multidisciplinary review highlights cryospheric studies incorporating spaceborne observations and hydrological models from diversified techniques/methodologies (e.g., multi-spectral optical data with thermal bands, SAR, InSAR, passive microwave, and altimetry), providing a valuable reference for what scientists have achieved in cryosphere change research and its hydrological effects on the Third Pole.

Global warming has led to extensive permafrost degradation, particularly in thermally vulnerablepermafrost in the marginal or transitional zones of altitudinal or latitudinal permafrost. However,comprehensive knowledge about microbial communities in response to rapid permafrostdegradation at large (or interregional) scales remains elusive. In this meta-analysis, existingpublished data were utilized to identify the distributive and co-occurrence patterns of themicrobiome in two interregional locations: the Qilian Mountains on the northeasternQinghai-Tibet Plateau(NE-QTP) and the Xing'anling Mountainsin Northeast China(NE-China).Both areas are situated in the marginal zone of large permafrost units. The results reveal that therapidly degrading permafrost did not overshadow the regional biogeographic pattern of themicrobial community. Instead, the results show some distinctive biogeographic patterns, ascharacterized by different groups of characteristic bacterial lineages in each of the two regions. SoilpH has emerged as a crucial controlling factor on the basis of the available environmental data.Network-basedanalysessuggestagenerallyhighlevelofnaturalconnectivityforbacterialnetworkson the NE-QTP; however, it collapses more drastically than that in NE-China if the environmentalperturbations exceed the tipping point. These findings indicate that the biogeographic patterns ofthe bacterial community structure are not significantly altered by permafrost degradation. Thisresearch provides valuable insights into the development of more effective management methodsfor microbiomes in rapidly degrading permafrost.