The Northwest region of China is a major battlefield and an important ecological and environmental security barrier to China’s western development. Flourishing the Belt and Road Initiative, climate change in this region has a direct impact on water resources, ecology, and environmental security. In the context of global climate change, Northwest China has shown an obvious and rapidly developing warming-wetting trend, which has resulted in increasingly prominent environmental and public security risks that are seriously affecting the sustainable development of the regional economy and society. This poses new challenges for climate change responses, water resource management, and disaster prevention and mitigation in this region. Research on the evolution characteristics, causes, and physical mechanisms of warming-wetting as well as its future trends and possible risks were reviewed. It further summarizes the current scientific consensus and existing problems, and finally looks forward to the key directions of future scientific research. A systematic review of the trend, causes, and future projection of climate warming-wetting in Northwest China will have important scientific implications for further research on this issue.

Climate extremes threaten human health, economic stability, and the safety of both natural and built environments. Compound extreme events are combinations of multiple climate drivers and/or hazards that contribute to societal or environmental risks, and their impacts on human society and natural ecosystems are often more serious and destructive than those of a single extreme event. Understanding the changes in compound extreme events is important for adaptation, mitigation strategies, and disaster risk management. Here, the definitions and connotations of compound extreme events are briefly discussed, including preconditioned, multivariate, temporal, and spatial compounding events. Subsequently, the progress in compound extreme event research is discussed in terms of temporal and spatial evolution characteristics, influencing factors, and future scenario projections. Given the problems in current research, we suggest that future studies should focus on studying compound extreme events regarding variable/index selection and threshold determination, dependence and interaction analysis among drivers and/or hazards, simulation performance evaluation and future projections, and their dynamic processes and disaster-causing mechanisms. Compound extreme events are expected to increase in frequency and intensity in a warming world, and many regions are projected to experience an increase in the probability of compound events with greater global warming. Therefore, we must improve our understanding of the causes and drivers of compound and cascade events.

Tropical Cyclones (TCs) are meteorological phenomena that affect middle and low latitudes worldwide. This paper systematically summarizes and reviews the research progress on the main characteristics, potential influencing factors, and influencing mechanisms of TCs at home and abroad, and summarizes and analyzes their changing trends under the climate background of GW. With the significant increase in global temperature, the sources and tracks of global TCs have shifted poleward, with a slight increase in translation speed, decrease in frequency, and increase in intensity; however, there are significant differences in each ocean. This paper focuses on reviewing the effects of volcanic activity, El Ni?o-Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO), solar radiation, Intertropical Convergence Zone (ITCZ), and aerosols on TC activity. Volcanic eruptions release a large amount of aerosols in the stratosphere, thereby reducing sea surface temperature and negatively affecting TCs. However, there are regional variations in this mechanism. ENSO and PDO modulate the global TC activity through teleconnections, while changes in solar activity and ITCZ are also associated with TC activity. Aerosols have opposite influence mechanisms on TCs at different development stages. Due to the lack of time length and the coarse resolution of most surrogate indicators of instrumental TC data, research on the impact of potential influencing factors on TCs under long-term climate fluctuations is severely restricted. In the future, we should be able to quantify the history of storm activities by finding high-resolution record carriers, thereby further analyzing the relationships between TCs and potential influencing factors, and improving our understanding of the change mechanism in TC activity under the influence of climate fluctuations.

Droughts spread through interrelated land-atmosphere systems and hydrological processes, and evolve into different types of droughts, such as hydrological, agricultural, ecological, and socioeconomic droughts, in different geographical and temporal contexts. Against the backdrop of global climate change and intensified human activities, the propagation and evolution of different types of drought present more uncertainties. Over the past decade, our understanding of the spatiotemporal characteristics, research methods, evolutionary processes, and driving factors of drought propagation has gradually deepened, but clear scientific views have not been realized. Beginning from the definition of drought propagation, this study systematically analyzed the scientific connotation of the problem and clarified the developmental stages of drought propagation research. Six quantitative research methods for current drought propagation were comprehensively summarized: threshold method and run theory, correlation analysis, causal analysis, cross-wavelet analysis, probability models, and meteorological-hydrological models. Furthermore, from the perspective of meteorological-hydrological and meteorological-agricultural drought propagation scenarios and drought propagation driving forces, the main acquired scientific knowledge was analyzed and summarized. The findings reveal the propagation order, stage threshold, spatiotemporal heterogeneity, and human-driven processes of drought propagation research worldwide. Finally, a series of challenges that future drought propagation research will face were analyzed. These include further exploration of spatiotemporal heterogeneity in the propagation process, bridging the gap between mathematical and physical knowledge to establish trustworthy models, and integrating cross-disciplinary knowledge to achieve a full-process analysis of propagation. The systematical analysis of the progress and challenges of domestic and international drought propagation research will provide key theoretical and methodological support for the next steps in drought disaster analysis and scientific management.

At around 20 km height in the atmosphere, a natural phenomenon occurs, in which the lower westerly (easterly) zonal wind changes into the upper easterly (westerly) zonal wind during a specific season, while the meridional wind is very small. This transition layer of the zonal wind is called stratospheric Quasi-Zero Wind Layer (QZWL). The low speed and direction transition of the wind in the QZWL are beneficial for stratospheric airships, high-altitude balloons, and other weakly powered or unpowered near-space vehicles, allowing them to stay there for longer periods. The characteristics of the QZWL with time in the northern hemisphere, the entire China, and key regions in China were summarized based on the QZWL results. The influence mechanisms and characteristics of the thermal wind, stratospheric Quasi-Biennial Oscillation (QBO), Stratospheric Sudden Warming (SSW), eddy flux transport of planetary wave, South Asia high and subtropical westerly jet on the QZWL formation were systematically analyzed. The advantages and disadvantages of MST radar, laser radar, sounding rocket and upper-air balloon in QZWL detection and some relevant facts were compared and analyzed. The advantages and disadvantages of middle atmosphere modeling and numerical weather modeling regarding QZWL forecasting were summarized. Numerical weather modeling is currently the main method for QZWL forecasting and meteorological support, and diagnostic schemes, such as the bottom height and thickness of the QZWL, are the basis for the quantitative study of the refined structure and evolution of the QZWL. The working principle of stratospheric vehicles using the QZWL is summarized. Finally, prospects regarding the key directions of future scientific research are presented. This review of the research progress on the QZWL will provide the basis for the future in-depth study of the QZWL and the deployment and meteorological support of stratospheric vehicles.

Human activities have changed the air oxygen content in urban areas and threatened the regional atmospheric oxygen balance. However, studies on urban atmospheric oxygen (O₂) remain limited, and a systematic assessment of the mechanisms that drive urban O₂ variability is not yet possible. Therefore, the long-term observation of atmospheric O₂ in urban areas is of utmost importance. This study provides an in-depth overview of the Lanzhou online atmospheric oxygen observation platform, which is the first in situ, high-precision, continuous atmospheric O₂ observation platform in China. The platform uses a gas chromatography-thermal conductivity detector (GC-TCD) method to measure the atmospheric O₂ content and establishes an XGBoost-based correction model for atmospheric O₂ observation data. After correction, the observation system error of atmospheric O₂ has significantly reduced to -0.68 μmol/mol. The observation results showed that atmospheric O₂ has clear seasonal and daily variation characteristics and good correspondence with urban human activity indicators (NOx). Based on the capabilities of the atmospheric oxygen observation platform demonstrated in this study, the platform can detect microvariations in atmospheric O₂ against a high background, providing crucial data to support research into urban atmospheric O₂ levels. Due to the close relationship between carbon and oxygen cycles, the long-term observation of atmospheric O₂ can be a scientific basis for establishing regionally appropriate “double carbon” practical paths.

With the development of spaceborne low-light imagers， extremely low-magnitude nocturnal visible radiance can accurately be detected. After accurate radiometric calibration， quantitative applications of satellite-based low-light imager observation data attract particularly increased scientific interest. This investigation systematically summarizes the advances in applications and research of satellite-based low-light imager data in the atmospheric， marine， and environmental sciences at night. First， the development history of satellite-based low-light imager payload is briefly introduced. Subsequently， the typical applications of low-light imager data in the atmospheric， marine， and environmental fields and the corresponding new scientific discoveries are summarized. Finally， considering new scientific objectives， advanced design concepts and application prospects for future satellite-based low-light imagers are proposed and discussed.

The Diurnal Cycle of Precipitation (DCP) is the result of various dynamic and thermodynamic processes in the climate system and is closely related to the water cycle and land-atmosphere interactions. In North China, the DCP is influenced by factors such as valley wind circulation, boundary layer inertial oscillations, and sea-land breeze circulation, exhibiting two peaks during the early morning and afternoon. In addition, the DCP in North China is influenced by anthropogenic aerosol emissions. This study introduces the fundamental characteristics and factors influencing the DCP in North China and summarizes recent research on the connection between the DCP and land-atmosphere coupling in North China, the modeling of the DCP, and the influence of aerosols on the DCP. The existing scientific knowledge is synthesized, and its shortcomings and challenges are outlined. Overall, investigating the DCP and its influencing factors can help us better understand the mechanisms of precipitation formation and evolution. This provides scientific support for enhancing the accuracy of fine-scale precipitation forecasting.

The Tibetan Plateau (TP), Iranian Plateau (IP), and Mongolian Plateau (MP) belong to Asian high-altitude regions. Thermal forcing over the three plateaus is important in contemporaneous and subsequent weather and climate in China. Examination of the spatial and temporal variation characteristics of surface sensible heat over the three plateaus revealed remarkable interannual and interdecadal changes attributable to global warming that occurred from the end of the 20th century to the beginning of the 21st century. Their relationships and possible mechanisms are discussed. A summary of the research progress on the impact of surface thermal conditions over the three plateaus on the weather and climate of China during spring and summer revealed three findings. First, over the TP, sensible heating has a significant impact on the formation, development, and eastward movement of the TP vortex, which induces rainstorms in the eastern part of China with an appropriate circulation background. Second, the Tibetan-Iranian Plateau (TIP) “sensible heat driven air-pump” favors the development of upward flow over the Asian monsoon region. The combined contribution of TIP thermal condition is greater than their linear superposition to the summer precipitation in southern China. Third, the warmer and drier conditions in northern China are closely related to the compensatory downdraft induced by thermal forcing over the TP, IP, and MP. In addition, the abnormal surface heating of the three plateaus triggers abnormalities in local circulation and regulates the weather and climate over northern China through teleconnection patterns. The paper concludes with a discussion of future research considerations and challenges regarding the synergism of the TP, IP, and MP.

Evapotranspiration (ET) encompasses water loss through transpiration and evaporation from soil and water surfaces. Accurate observation of ET is essential for comprehending the ET process, and mechanism, as well as water-energy nexus and land-atmosphere feedback. ET serves as a pivotal link between the hydrological cycle and energy processes. In-situ measurements provide fundamental datasets for validating remotely sensed ET products. The surface renewal theory differs from the commonly used eddy covariance method in describing the physical ET process. Unlike the expensive sonic anemometers in the eddy covariance system, the surface renewal method is cost-effective because it uses a fine- diameter thermocouple to record high-frequency air temperature and estimate the sensible heat flux through coherent structures. The surface renewal method for measuring ET, with an accuracy comparable to that of the eddy covariance system, and it has been widely applied for ET measurements in America and Europe. Recognizing the substantial potential of this method, this paper reviews the theory of surface renewal and research advancements in the method made over the past 30 years. Additionally, preliminary studies related to ET measurements in China using the surface renewal method are also presented. By summarizing this progress and exploring the challenges in the application of the surface renewal method, we can enhance our understanding and promote a variety of domestic ET observation methods.

Guizhou Province, characterized by unique topography and complex climatic conditions, offers an excellent opportunity to study spectral surface albedo (short-wave, near-infrared, and visible light). Analyzing this refines surface parameters and understands the characteristics of solar spectral radiation but also provides scientific references to explore the physical processes of the relevant spectral radiation, variables in the process of energy conversion of the earth-air system in mountainous areas at low latitudes. Therefore, based on MCD43A3 albedo data, MCD15A2H Leaf Area Index (LAI), temperature, precipitation, land use, and soil moisture data, using anomalous variance analysis, Theil-Sen (T-S) and Mann-Kendall (M-K) trend analyses, and geophones, we analyzed the spatial and temporal trends and driving factors of spectral surface albedo in Guizhou Province. The results show that \mathrm{①} interannual changes in spectral surface albedo were in the order of size: near-infrared>short-wave>visible. In addition to visible surface albedo being on the rise (the three bands of surface albedo high-value area were basically the same), there was a line from the northeast to the southwest, and the western distribution of the characteristics of the County of Weining; \mathrm{②} considering seasonal changes, the size order of short-wave and near-infrared surface albedo was the same, as follows: summer>autumn>spring>winter and that of visible surface albedo was spring>winter. The sizes of short-wave and short-wave albedo were the same, as follows: summer> autumn>spring>winter, and that of visible surface albedo was: spring>winter>autumn>summer; \mathrm{③} the driving factors of spectral surface albedo were LAI, followed by land use. The results of this study reveal spatial and temporal variations and driving mechanisms of the spectral surface albedo in Guizhou, which can provide a reference for the ecological protection of mountainous areas in Guizhou.

Data-driven methods with deep learning as their core have been gradually applied in Earth science; however, challenges remain regarding the interpretability of models and physical consistency. With the background of remote sensing big data, combining deep learning and data assimilation methods to develop new techniques for the simulation and prediction of terrestrial water cycle processes has become an important research direction in Earth science. Τhe progress in deep learning in recent years combines improving the quality of observation data of terrestrial water cycle components and reducing the uncertainty of physical models. Furthermore, the key scientific issues regarding data assimilation in terrestrial hydrology based on deep learning fusing remote sensing big data are classified according to the observations, physical models, and system integration: \mathrm{①} How can the temporal and spatial representativeness of samples be enhanced when deep learning inverts remote sensing products? \mathrm{②} How can a new physics-guided deep learning method be developed within the framework of data assimilation? \mathrm{③} How can the predictability of the terrestrial water cycle be improved through the “data-model” dual drive? Relevant research and exploration should help promote the in-depth application of the “data-model” hybrid modeling method in the field of hydrology and improve the simulation and prediction capacity of the terrestrial water cycle process.

Cherts are widely distributed in Precambrian to Cenozoic orogenic belts and sedimentary basins.The origin and depositional environment of cherts are of great importance in understanding the regional paleogeographic, paleotectonic, paleo-ocean, and paleoclimate evolutions. After summarizing the existing geochemical methods for identifying the origin and depositional environment of cherts, it is concluded that the identification of the origin of cherts should focus on authigenic siliceous minerals and use exotic interfusion materials as references. Effective proxies include Al, Ti, Fe, Th, Ge/Si, Si isotopes, Rare Earth Elements (REE), etc. The essence of the discrimination of the depositional environment of cherts is to distinguish the relative contribution of terrigenous and hydrothermal materials; although previous discrimination diagrams provide practicability, they still involve errors and need to be used carefully. As an important type, cherts outcropped in orogenic belts are closely related to the Ocean Plate Stratigraphy (OPS). Here, a correlation scheme between them has been established. According to this correlation scheme, cherts outcropped in orogenic belts can be divided into the ridge subtype, pelagic abyssal plain subtype Ⅰ, pelagic abyssal plain subtype Ⅱ, ocean island-seamount subtype, intra-oceanic arc subtype, and forearc trench subtype. The cherts-OPS correlation scheme not only provides a basis for reconstructing the original sequence of the accretionary complex in an orogenic belt using cherts, but also considers cherts as important evidence for distinguishing the main oceanic basins from the back-arc and inter-arc oceanic basins. Taking the Eocene cherty ooze obtained by oceanic drilling in the Pacific as an example, it is suggested that the main oceanic basin is characterized by deep-sea plain cherty rocks that are almost unaffected by terrigenous and hydrothermal materials. These cherty rocks have geochemical characteristics such as Fe/Ti values close to 20, Eu/Eu* values close to 1.1 and negative Ce/Ce* values. These results provide new perspectives and references for subsequent research on cherts in orogenic belts.

Ecological resilience, the ability of an ecosystem to absorb and adapt to environmental change to maintain its sustainability, was first systematically introduced by the Canadian ecologist C.S. Holling in 1973 and has since rapidly attracted attention and been used across multiple disciplines. In the context of global change, the response of terrestrial ecosystems to increasingly intensifying arid environments, specifically the spatial patterns and evolutionary mechanisms of vegetation ecological resilience under drought stress, has become a core focus of current ecological and ecohydrological research. In recent years, numerous studies have been conducted on the relationship between vegetation change and water stress, enhancing our understanding of this mechanism. However, the interpretation of the ecological resilience of vegetation varies widely and remains controversial, and one of the main reasons for this is that the understanding of the connotations of ecological resilience is not yet unified. To address this issue, we synthesized the views of researchers worldwide and suggested that the analysis of ecological resilience should not only consider the system resistance and recovery capacity under drought events but also the system response and adaptation behavior under changing environments from the perspective of system evolution. These include resistance, recovery, and adaptation, which should be the three most important dimensions for determining ecological resilience. Focusing on these three main dimensions, we reviewed the results of recent research conducted globally and summarized the current understanding of ecological resilience and the key issues to be addressed in terms of spatial patterns, impact mechanisms, and adaptation strategies for ecological resilience. Through an analysis of the concept of ecological resilience and the current state of research, we hope to promote academic discussions on the definition of ecological resilience and its quantitative methods to facilitate an understanding of the evolution of resilience and its underlying mechanisms.

Dynamic monitoring of suspended sediment in rivers has important application values for channel changes, safe operation of water conservancy projects, ecology, and environmental protection. Real-time remote sensing technology can monitor suspended sediment in sizeable regional river water bodies. Compared to large bodies of water such as oceans and lakes, remote sensing of suspended sediment in rivers has received less attention. Existing research has primarily focused on estuarine areas where rivers enter the sea. This study systematically summarizes published data sources and models of satellite remote sensing of suspended sediment in rivers worldwide to fully utilize the advantages of multi-source satellite remote sensing data with different temporal, spatial, and spectral resolutions and to realize remote sensing monitoring of suspended sediment transport in a broader area and at different river levels. The difficulties and challenges of satellite remote sensing of suspended sediments in rivers are discussed. On this basis, the future development of remote sensing monitoring of suspended sediment in rivers has been viewed from three perspectives: removing atmospheric correction of the proximity effect, concentration on remote sensing considering suspended sediment particle size distribution, and three-dimensional remote sensing of suspended sediment transport flux.

The National Natural Science Foundation of China (NSFC) has received widespread attention as the primary funding institution for basic scientific research in China. Here, we analyze the results of the proposals received by the Division of Geography, Department of Earth Sciences, National Natural Science Foundation of China, in 2023. An analysis of the proposal review and funding processes was undertaken for three sub-disciplines (Physical Geography, Human Geography and Geographic Informatics); three types of projects (general program, Young Scientists Funding Program, and Regional Funding Project); and four scientific themes or focus areas, as formulated by the NSFC. In addition, issues to be noted in the proposal submission and peer review are discussed. For projects completed by the end of 2022, we first analyzed the publication status of SCI/SSCI/EI/CSCD/CSSCI indexed articles in various project categories and then focused on the representative achievements.

Hydroxylamine (NH₂OH) is one of the most active trace forms of nitrogen in oceans, and it is the key intermediate product of many nitrogen cycle processes, such as ammonia oxidation, dissimilatory nitrate reduction to ammonium and anaerobic ammonia oxidation. Therefore, it is an important component of the marine nitrogen cycle network framework. Concurrently, NH₂OH is an important precursor of the greenhouse gas nitrous oxide (N₂O), closely related to the production and release of marine N₂O. Accordingly, a systematic understanding of the source and sink, spatiotemporal variations, and regulatory mechanisms of NH₂OH in the ocean is essential to understand the oceanic nitrogen cycle and climate effects. However, the nanomolar concentration of NH₂OH in the ocean and its complex and active migration and transformation processes render the oceanographic community’s understanding of NH₂OH unclear. Current research on marine NH₂OH is systematically reviewed, focusing on the potential source and sink processes of NH₂OH, the determination methods of NH₂OH, the possible contribution of NH₂OH to marine N₂O, and the distribution characteristics and potential impact factors of NH₂OH in the ocean. Finally, the problems and difficulties in determining NH₂OH and the possible mechanisms affecting its distribution are summarized, and suggestions and prospects for future research on marine NH₂OH are discussed.

The accurate acquisition of in situ particle detection information in clouds is important in revealing the physical mechanism of cloud precipitation formation, improving the parameterization scheme of numerical weather prediction models, and evaluating the seeding effect of weather modification. Digital holographic measurement technology can obtain three-dimensional positioning information of particles and has advantages, including a wide measurement range (μm to mm), high spatial resolution (mm magnitude), and accurate determination of instrument sampling space. Therefore, it has wide application prospects in cloud microphysics observations. This study summarizes the current situation of holographic cloud particle imagers worldwide. Several key technical issues involved in the development of instruments were analyzed, such as the holographic optical path design, mechanical protection design, and hologram processing. Applications of holographic observations to reveal the freezing mechanism of ice crystals in mixed-phase clouds and microphysical mechanisms in clouds with turbulent mixing were introduced. Finally, certain thoughts and prospects were discussed from the perspective of technology application, which can provide a reference for the development of related instruments and research on cloud microphysics observations.

We analyzed the submissions, acceptances, reviews, and grant funding of various projects managed by the Environmental Geosciences Division，National Natural Science Foundation of China in 2023, and we summarized the outcomes of funded and completed projects of this discipline at the end of 2022. Based on this analysis, the advances in environmental geosciences are discussed.

As a result of global warming, the melting of ice-rich permafrost causes the ground to collapse, thereby creating thermokarst lakes, while the greenhouse effect caused by the concurrent release of greenhouse gases results in a positive feedback with climate warming. Microorganisms play important roles in various aspects of the carbon cycle. Understanding the mechanisms of microbial regulation of the carbon cycle in thermally melting lakes is of great significance for coping with future climate change. Therefore, by combining previous studies, this paper first elucidates the formation process of thermokarst lakes and the microorganisms inhabiting these special habitats; subsequently, the main microorganisms involved in organic carbon decomposition, methane production, and methane oxidation, and the regulation mechanisms and influencing factors are analyzed in detail. Based on this analysis, we conclude the following: \mathrm{①} The organic matter in thermokarst lakes originates from the land, while some nutrients, such as phosphates, plant biopolymers, and leucine residues, are also transported from the land to the water. \mathrm{②} With improvements in temperature and aeration conditions, the availability of most nutrients increases the genetic diversity of microorganisms and promotes their roles in organic carbon decomposition. Changes in temperature, substrate, dissolved oxygen, and microbial community affect the processes of methane production, methane oxidation, and carbon sequestration, thereby affecting the carbon cycle. \mathrm{③} Some deficiencies in previous studies are summarized, and a new research perspective is proposed to deepen our understanding of microbial involvement in the carbon cycle in thermokarst lakes. With the help of metagenomic technology and incubation, the regulatory mechanisms of microbes for the carbon cycle can be revealed more clearly, and field observations of carbon emissions from thermokarst lakes under different environmental conditions can be strengthened. Exploring the use of microbes for mitigating the negative effects of climate change should be based on the above fundamental research.

Ozone is among the most important trace gases in Earth’s atmosphere and plays a crucial role in both climate change and ecology. Tropospheric ozone is an important component of photochemical smog, and its variations are closely related to human activity. Monitoring of tropospheric ozone based on satellite remote sensing can help us better understand and quantitatively explain the characteristics of tropospheric ozone changes in different seasons, times, and regions, and explore the mechanism of ozone generation in the troposphere. With the comprehensive development of satellite remote sensing techniques, ozone remote sensing products (e.g., total ozone, profiles, etc.) have improved significantly in terms of accuracy and spatiotemporal resolution. However, the accuracy of tropospheric ozone products is still not sufficient for the current scientific application of the atmospheric composition of the troposphere due to the weak satellite signals and complexity of the subsurface. This review focuses on satellite remote sensing of tropospheric ozone. It outlines and analyzes the development history and current status of ozone satellite remote sensing payloads and discusses the characteristics and applicability of remote sensing retrieval algorithms based on different technologies (direct and indirect retrieval, multiband joint retrieval, collaborated nadir-limb retrieval, and innovative algorithms based on machine learning techniques). It further discusses the application of satellite remote sensing for the provision of reliable tropospheric ozone observation data at the global and regional scales. Overall, this review envisions the application of satellite remote sensing for providing reliable tropospheric ozone observations at the global and regional scales.

Inland water is an important source of global methane (CH₄) emissions, and CH₄ emitted through ebullition accounts for a large proportion of the total CH₄ emissions from inland waters. Here, the latest progress in domestic and international research has been systematically summarized to introduce the generation, transport, oxidation, and release of CH₄ via ebullition in inland waters as well as the methods and techniques for measuring CH₄ ebullition. Subsequently, temporal and spatial variations in CH₄ ebullition from global inland water were compared at different temporal and spatial scales. In addition, the mechanisms of the relevant influencing factors in the processes of CH₄ generation and ebullition are further summarized, and current development and applications of CH₄ ebullition models are discussed. Finally, potential research directions and challenges related to CH₄ ebullition from inland water are proposed, aiming to provide a basis for subsequent research on CH₄ ebullition, investigation of process and control mechanisms, and model development and estimation in this field.

Watershed geomorphology and river network structure controlled by tectonic frameworks, regional climate, vegetation, and biological factors are the combined results of the long-term internal and external forces of the Earth. Owing to the different tectonic, lithological, and climatic conditions in various regions, different watersheds have different geomorphic and river network structural characteristics that influence hydrological response mechanisms. In this study, the characteristic parameters for a quantitative description of the watershed geomorphic system and river network morphology are presented, and the impacts of tectonics, lithology, climate, and other factors on watershed geomorphology and river network structures are reviewed. Based on this, it is emphasized that reproducing the evolution of watershed geomorphology and quantifying its main controlling factors is the main problem. Subsequently, the birth, development, and application of the geomorphic evolution model are expounded. Finally, it is suggested that the main future development direction should involve combining traditional geomorphological research methods and geomorphic evolution models to study the influencing mechanisms of watershed geomorphology and river network structure.

The Paleoproterozoic Great Oxidation Event (GOE, approximately 2.43~2.06 Ga) is the first significant atmospheric oxygen increase and fundamentally changed the environment and habitability of the Earth. This study summarizes the research progress on the GOE and related carbon cycle perturbation events in the early and middle Paleoproterozoic, focusing on the time frame, initiation process, and mechanism of the GOE, extremely δ¹³C_carb-positive excursion event (Lomagundi-Jatuli event), and carbon cycle perturbation events after the GOE. The initiation of the GOE was intermittent, and research on the initiation mechanism presents diverse viewpoints. The atmosphere-ocean system experienced oxidation and deoxygenation processes during the Lomagundi-Jatuli event, in which the initiation mechanism may have been caused by the increase in ocean primary productivity during this period, but the influence of other mechanisms (such as the deep carbon cycle of the Earth) cannot be ruled out. After the Lomagundi-Jatuli event, global organic carbon burial increased significantly and lasted until approximately 1.7 Ga (Shunga event), during which there was a δ¹³C_carb-negative excursion event (Shunga-Francevillian event). The mechanism of the Shunga and Shunga-Francevillian events remains to be studied.

Groundwater dating is one of the key links in the study of water cycles, especially in hydrogeology. However, the proposed concept of groundwater age and its dating methods are complex and difficult to distinguish, which hinders practical application and further development. This study systematically examines the concept of groundwater age and resident time that often appear in academic circles, simultaneously differentiating and analyzing the derived idealized age, tracer age, apparent age, age distribution, and model age, and comprehensively analyzes and draws a relationship diagram among the definitions. Data of the sample collection and analysis methods, advantages, and disadvantages of the natural isotopes of groundwater dating (including the radionuclide decay method and stable nuclide linear calculation method), and the methods for detecting radionuclides produced by human activities and greenhouse gas tracers are summarized and reviewed. There are two perspectives of groundwater dating methods: water sample points and water systems. The model interpretation methods of multi-tracer combination and age data from the perspective of the water body system (dynamic) are reviewed. Furthermore, we synthetically state that the groundwater dating method should be determined comprehensively according to the research objectives and range of application of tracers, with more attention paid to the study of age distribution characterizing the spatiotemporal dynamics of groundwater systems. Future studies should strengthen the integration and model research of multidisciplinary data, such as geology, hydrology, and hydrochemistry, to establish a numerical model of groundwater flow to describe age distribution and model research.

Quantitative assessments of progress towards Sustainable Development Goals (SDGs) and the complex interactions of indicators are critical for monitoring the achievement of SDGs and guiding policymaking and implementation. Based on Big Earth Data and the SDGs global indicator framework, an index system for evaluating progress towards SDGs in frontier, multi-ethnic underdeveloped areas was developed from the perspective of social, economic, and environmental dimensions and included 70 indicators. The study area was the National Innovation Demonstration Zone (Lincang) for the 2030 Agenda for Sustainable Development. The model incorporated regional characteristics and data acquisitioned from Lincang in 2015-2020 through field research. Consequently, we calculated the social, economic, and environmental sub-indices and integrated index of sustainable development of Lincang City from 2015 to 2020, evaluated the progress trend of SDGs and indicators, and proposed key challenges and solutions for the sustainable development of Lincang City. Research shows that the integrated index and the social, economic, and environmental sub-indices of sustainable development have shown an increasing trend from 2015 to 2020. In terms of the SDGs, progress was achieved with respect to all 16 SDGs. The average annual growth rate of SDG 5 was the highest, whereas that of SDG 13 remained unchanged. In addition, 81% of indicators showed acceptable progress. This study provides a reference for sustainable development planning in other typical demonstration areas and underdeveloped mountainous areas in China and worldwide.

Marine carbon storage plays a crucial role in reducing global greenhouse gas emissions. To ensure the efficient and safe storage of CO₂, it is imperative to monitor the potential migration of CO₂ before, during, and after injection. Current methods for monitoring marine carbon storage encompass built-in sensor monitoring focusing on the seabed wellbore, geophysical monitoring targeting reservoirs and caprocks, and marine environmental monitoring focusing on the seafloor and water column. These three methods can be used to obtain temperature/pressure/acoustic data near the injection/monitoring wellbore, seismic/electromagnetic/gravity data of deep reservoirs and caprocks, and acoustic/chemical/oceanographic data of near-bottom sedimentary layers and seawater, respectively. Analyzing these datasets is expected to reveal the migration characteristics of CO₂ injected into the formation. However, the integrated use of relevant monitoring methods and technologies and the design of high-quality monitoring strategies currently pose significant challenges for both academic and engineering communities. To enable scientific and systematic monitoring of the safety of marine carbon storage, offering essential guidance for offshore storage operations, and concurrently enhancing monitoring efficiency while reducing monitoring costs, we have compiled the fundamental principles, application status, and challenges encountered by different monitoring methods and technologies. We also anticipate future development of monitoring technologies for marine carbon storage.

Globalization and elevated atmospheric Nitrogen (N) deposition have significantly altered the terrestrial carbon cycle. Soil microbial Carbon Use Efficiency (CUE) plays a key role in adjusting soil cycling rates and processes and is also an important parameter in soil C cycle models. However, the effects of elevated N deposition on soil microbial CUE are often inconsistent, which limits the reliability of predictions of both soil C cycle dynamics and C storage capacity under global changes. Here, we review advances in research on soil microbial CUE and measurement methods. We further explore the mechanisms underlying the effects of increased nitrogen deposition on CUE from both biological and abiotic perspectives in forest ecosystems. In terms of biological mechanisms, N deposition can affect CUE by changing microbial biomass and community structure and by regulating microbial enzyme activities. In terms of abiotic mechanisms, N deposition can affect CUE by changing the N addition-induced changes in the soil nitrogen state, soil stoichiometry, soil pH, and aboveground vegetation dynamics (such as root exudates and litter input), which can independently or jointly affect soil microbial CUE. In general, moderate nitrogen deposition can alleviate ecosystem nitrogen limitation and stimulate microbial activity, thus increasing soil microbial CUE. In contrast, excessive N deposition decreases microbial CUE by inhibiting microbial growth. Lastly, the potential research activities and recommendations for future research are presented. Therefore, it is imperative to optimize the determination of microbial CUE for comparative research among different ecosystems. At temporal and spatial scales, more attention should be paid to the interaction effects of multiple factors under global changes, so that there is a strong theoretical basis for evaluating and predicting the soil carbon sequestration capacity in forest ecosystems.

N₂O is an important greenhouse gas that also damages the ozone layer. N₂O emissions have been observed during microalgae cultivation and in microalgae-based ecosystems, such as eutrophic lakes. However, little has been reported on the important role of the N₂O balance in algae and the potential algal N₂O production pathways. A review of recent relevant studies on N₂O synthesis and fixation by algae shows that the studies mainly focus on the relationship between algae and N₂O emissions, several possible pathways of N₂O production and consumption in algae, the influence of the algal microenvironment on the distribution pattern of N₂O, and the potential impacts on global climate change. However, the Intergovernmental Panel on Climate Change currently does not consider the possible N₂O emissions during algal blooms or algal aquaculture; hence, it is necessary to intensify experimental studies related to algal N₂O production globally to take important steps towards a comprehensive clarification of the important roles of algae in N₂O emission and fixation and a comprehensive assessment of greenhouse gas emissions from aquatic ecosystems.

From 2015 to 2017, the Western Cape province in South Africa suffered a severe drought, resulting in an extreme shortage of water resources in the city, making its capital, Cape Town, the first modern city in human history to face the threat of a “Day Zero” disaster (i.e., the day when the city’s water taps are turned off). However, the interaction mechanisms and processes of various disaster-causing factors remain unclear, and how to scientifically cope with the natural precipitation variation mode by man-made water-supply management needs to be further explored. Therefore, this paper explores the key stages, spatial distribution, and management benefits from the three dimensions of meteorological drought, hydrological drought, and urban water supply management. The results show the following: \mathrm{①} The Western Cape experienced a significant increase in the area and intensity of meteorological drought from 2015 to 2017, with the most severe drought conditions occurring in May 2017. Compared with the Standardized Precipitation Index (SPI), the drought detected by Standardized Precipitation Evapotranspiration Index (SPEI) was more significant. \mathrm{②} The hydrological drought conditions in the Western Cape in May 2017 were the most severe. This is broadly consistent with the pattern of spatial and temporal characteristics of meteorological drought, reflecting the rapid spread of meteorological-hydrological drought. Both the Standardized Runoff Index (SRI) results and the change in reservoir water volume reflect water scarcity in the region, indicating that the drought event had a serious impact on the Western Cape, which relies heavily on rainfall and reservoir water supply. \mathrm{③} The Western Cape government adopted different levels of water restrictions and management policies in response to the evolution of this drought, effectively delaying and avoiding a “Day Zero” disaster; however, addressing the political and economic aspects of water inequality is still debatable and worth improving. This paper shows that urban drought problems involve multiple systems and interactions among the meteorology, hydrology, and water supply, and need to be monitored, understood, and mitigated in terms of the spatial and temporal processes.

The migration processes of the Cenozoic intracontinental foreland basins in western China provide valuable insights into the shortening and uplifting histories of coupled orogenic belts. A comprehensive review of the research methodologies used to reconstruct foreland basin migration and its quantitative relationship with crustal shortening enables us to uncover the structural implications of this process. Seismic reflection profiles crossing the foreland basins image the stratal onlaps and conglomerate-sandstone transitions in the basins. Based on the interpretations of seismic profiles, the migration rate of foreland basins can be determined by integrating stratigraphic age constraints derived from magnetostratigraphy. The variations in the rates correspond to the variations in the underthrusting rates of the foreland basin basement relative to the orogenic belts, revealing changes in the horizontal crustal shortening rates absorbed by the orogenic belts. Through a comparative analysis of the migration processes of the rejuvenated intracontinental foreland basins on the northern side of the West Kunlun Mountains and the southern and northern sides of the Tianshan Mountains, these two mountains contrast markedly in terms of crustal shortening rates and deformation patterns since approximately 30 Ma. The contrast between these mountains indicates differences in their dynamic mechanisms. Furthermore, this method holds great potential for future applications in unraveling the growth process of the northeastern margin of the Qinghai-Tibet Plateau.

Division V (Atmospheric Discipline) of the Department of Earth Sciences, National Natural Science Foundation of China (NSFC), successfully completed the application, review, funding, and conclusion of the centralized receipt of the Program in 2023. In terms of program applications, Division V of the Department of Earth Sciences received 1 928 applications from the General Program, Young Scientists Fund, and Fund for Less Developed Regions in 2023, indicating an increase of 6.1% over the applications in 2022. Two applications were rejected because of non-compliance with management standards in 2023, and this result is an improvement compared to previous years. Atmospheric Discipline received 62 applications for National Science Fund for Distinguished Young Scholars, 92 applications for Excellent Young Scientists Fund, and 49 applications for key program in the field of ‘Weather, climate, and associated sustainable development.’ From the perspective of reviews, the comprehensive evaluation scores of communication reviews for the General Program, Young Scientists Fund, and Fund for Less Developed Regions increased compared to the previous two years. This review clarifies the positioning of the “supporting technology” section to support programs that are truly engaged in key technology research and development. In terms of funding, the total number of the three types of funds reached 417, and the average funding rate was 21.6%, which was lower than that in 2022. In total, 319 projects were concluded in 2022, and performance indicators, such as the number of published papers, were comparable to those in previous years.

Rivers connect the terrestrial landscape and oceans and are considered “bioreactors” of carbon. Understanding the carbon cycling processes in rivers and constructing numerical models for riverine carbon cycling is imperative to estimate regional and global carbon budgets. The summary and discussion of the development and application of riverine carbon cycling models remains inadequate. This study reviewed the mechanisms and models of riverine carbon cycling based on a comprehensive literature review. First, we briefly overview the critical processes in migrating and transforming various carbon components, including particulate organic carbon, dissolved inorganic carbon, and dissolved organic carbon. Riverine carbon cycling models are classified into two types: statistical and process-based. The representative models’ simulation methods, applications, advantages, and disadvantages were compared. Based on statistical or machine learning methods, empirical statistical models establish the relationship between the riverine carbon flux and environmental factors. This type of model is simple but has poor extrapolation and universality. Process-based models are based on land surface or hydrological models coupled with river carbon cycling-related biogeochemical processes. This model simulates and predicts variations in different riverine carbon fluxes and is more reliable but complicated. Such models typically focus on different scientific problems, and the representations of riverine carbon cycling-related processes differ among these models. Simulation research on riverine carbon cycling is still in its early stages; however, many shortcomings remain. For example, the representations of terrestrial and aquatic carbon cycling and human activities in existing riverine carbon cycling models are insufficient; thus, they cannot accurately simulate and predict long-term changes in riverine carbon cycling. In the future, it will be necessary to strengthen observations of river carbon cycling processes and improve our understanding of terrestrial and aquatic carbon cycling to represent the mechanisms and processes in the model. This will improve the accuracy of riverine carbon cycling simulations and provide a scientific basis for China to achieve its double-carbon goals.

The Anthropocene Working Group (AWG) of the International Commission on Stratigraphy voted that the Anthropocene should be defined by a Global boundary Stratotype Section and Point (GSSP or ‘golden spike’) as a formal chronostratigraphic unit. Increasing evidence has shown that human activities have drastically intensified since the mid-twentieth century, altering the original rate and direction of Earth’s evolution, triggering a profound impact on Earth’s environment, and leaving their imprint on geological records through physical, chemical, and biological markers. Consequently, the 1950s was assumed to be the ideal onset of the Anthropocene. Currently, 12 candidate sites for the GSSP of the Anthropocene have been proposed for consideration by the AWG. Chinese researchers have made outstanding progress in recent years regarding the establishment of a system of proxies for human activities and the global comparison of the candidate sites for the GSSP of the Anthropocene. These proxies, including anthropogenic radioactive isotopes, microplastics, δ¹³C, δ¹⁵N, and diatoms, have great potential as markers of human activities. These proxies recorded in the sediments of Sihailongwan Maar Lake, which is far away from cities and less affected by human activities, indicate that this site is sensitive to global change. The concentrations of ^{239, 240}Pu have drastically increased since 1953 CE in the sediment profile collected from Sihailongwan Maar Lake. as Additionally, other proxies such as PAHs, ¹²⁹I, soot ¹⁴C, SCP (spheroidal carbonaceous particles), DNA, δ¹³C, and Pb exhibit synchronous changes near 1953 CE, indicating the onset of Anthropocene. Two sediment stratotype profiles collected from Sihailongwan Maar Lake and Beppu Bay, Japan, were selected by the AWG as auxiliary sections for the GSSP of the Anthropocene. The ultimate goal of Anthropocene science should be to deepen the theory and technological innovation of sustainable development of the Earth-humans system and adaptation based on clarifying the impact of human activities on the Earth system.

The Yangtze River is the largest river system in Asia, and its formation and evolution are of great significance for understanding the topography, climate change, biological evolution, and material cycles of East Asia. The Three Gorges lie in the central Yangtze Block, and its formation connects the drainage in the Sichuan Basin and the Jianghan Basin; therefore, it is regarded as one of the most critical events in the history of the Yangtze River. However, the debate over how and when the Three Gorges were formed has been ongoing for over a century. This study reviews the century-long debate, especially regarding the formation mechanism and age of the Three Gorges, to clarify the formation of the Yangtze Three Gorges. A comparison highlighted a conflict between the erosion time of the Three Gorges and the provenance analysis in the downstream basin, stemming from limitations in research ideas, objects, and methods. Determining the formation time of the Three Gorges necessitates a comprehensive approach that integrates gorge erosion and provenance analysis in the Jianghan Basin. Methods such as monazite fission track, cosmogenic nuclide dating, and geochemical analysis of single-grain minerals offer precise constraints on gorge erosion and aid in establishing a source-sink system between the Jianghan Basin and Sichuan Basin. Drawing on the principles of Earth system science and source-sink systems, this study proposes an analysis of tectonics, landforms, and climatic evolution to understand the evolution of large drainage systems such as the Yangtze River. In particular, a comprehensive analysis of the geochemical characteristics and exhumation histories of the Qinghai-Xizang Plateau, basin development, and geochemical characteristics of detritus minerals is required to investigate the evolutionary processes of large rivers such as the Yangtze River.

On August 24, 2023, the Japanese government started discharging the Fukushima Nuclear Contaminated Water (FNCW) into the North Pacific. This process is bound to pose radiation risks for the marine ecological environment. In this study, we analyzed the concentrations of major artificial radionuclides in the FNCW and estimated their inventories. Based on the data provided by the Tokyo Electric Power Company, we found that the concentrations of ³H in FNCW tanks as of March 2023 ranged from 1.9×10⁵ to 25.0×10⁵ Bq/L, significantly exceeding the maximum release concentration for ³H (6×10⁴ Bq/L) allowed by Japanese law. In addition, the concentrations of ⁹⁰Sr and ¹²⁹I in some FNCW tanks were higher than the corresponding maximum release concentrations (30 Bq/L for ⁹⁰Sr and 9 Bq/L for ¹²⁹I) allowed by Japanese law. The inventories of ³H and ¹²⁹I in the FNCW before the discharge were estimated to be 0.9 and 6.2×10⁹ Bq, respectively, i.e., comparable to the leakage amounts of ³H (0.1~1.0 PBq) and ¹²⁹I (6.9×10⁹ Bq) to the ocean during the nuclear accident stage. We further discuss the migration and behavior of typical Fukushima radionuclides (e.g., ³H, ¹⁴C, ⁶⁰Co, ⁹⁰Sr, ¹²⁹I, ^{134, 137}Cs, and ^{239, 240}Pu) in marine environments from three aspects: \mathrm{①} transport of Fukushima radionuclides by ocean currents in the Pacific; \mathrm{②} sediment adsorption to radionuclides; and \mathrm{③} marine biota uptake of radionuclides. This study is expected to provide scientific foundations and insights for radiation monitoring and risk assessment, which may be required for an appropriate response to the discharge of the FNCW.

Ocean aerosols are of important because of their climatic and environmental effects. When bubbles in seawater rise to the surface and burst, they enrich the surface-active substances present in the sea-surface microlayer into Sea Spray Aerosol (SSA), thus affecting their physical and chemical properties. In this study, the sources and quantitative characterization methods for marine surface-active substances are reviewed. The effects of surface-active substances on the concentration and particle size distribution of SSA are addressed, and the influencing mechanisms of hygroscopicity, cloud condensation nucleation activity, and ice nucleation activity are summarized. Owing to different sources, types, and other environmental conditions; the effects of surface-active substances on SSA generation and physicochemical properties vary significantly, making it difficult to study the environmental and climatic effects of SSA. In the future, further observational and modeling research on surface-active substances is required to provide scientific support for improved regional and global modeling of SSA.

The Intergovernmental Panel on Climate Change Sixth Assessment Report (AR6) stresses threat of the continuous melting of polar ice sheets and hence rising global sea levels on our socioeconomic and living environment. However, large uncertainty remains in future projections of Earth’s ice sheet, which might be reduced by improving our understanding of its evolution history and associated dynamics by ice-sheet modeling. Glacial index method is an effective approach to investigate transient ice sheet change by interpolating discrete climate forcing into continuous climate forcing based on paleoclimate proxies. This indicates the choice of paleoclimate proxy might be of crucial impact on simulated transient ice sheet change. Here we investigate this issue with a focus on the tempo-spatial evolution of the Northern Hemisphere ice sheet during the last glacial cycle using two sets (six in total) of proxies representing global sea level and temperature changes, respectively. Three key conclusions are summarized in the following. First, the characteristics of proxy trajectory have a significant influence on the simulated ice volume’s evolutionary characteristics. Second, the presence of millennial-scale abrupt climate change events in proxies lowers the simulated overall ice volume when tendency and amplitude of proxies are similar. Third, ice sheet extent is constrained by the summer 0 °C isotherm which is modulated by the tendency and amplitude of different proxies, even when subjected to the same Last Glacial Maximum climate forcing. Therefore, our results emphasize the need to carefully consider the characteristics of paleoclimate proxies when using the glacial index method for studying global ice sheet changes over time. Understanding the limitations and potential biases associated with the chosen proxies is crucial to avoid misinterpretation and overstatement of modeling results.

The early Paleogene was a typical greenhouse climate period in the Cenozoic, during which a series of rapid and short-lived warming events (termed “hyperthermals”) occurred. Hyperthermals were characterized by negative carbon isotope excursion. Among them, the Dan-C2 thermal event of the early Danian is considered to be the first to occur after the biological mass extinction at the end of the Cretaceous; thus, its environmental significance and ecological effects have received widespread attention. However, as research continues, controversies regarding the Dan-C2 event continue to grow: \mathrm{①} The global significance is controversial; in the marine records, the δ¹³C negative excursions during the Dan-C2 event were restricted to planktonic foraminifera and bulk records in parts of the Atlantic and Tethys Oceans, while benthic foraminifera rarely recorded this event, suggesting that it may only be a regional carbon perturbation event. Furthermore, the warming indicated by the oxygen isotopes (δ¹⁸O) of bulk and planktonic foraminifera during this event was limited to surface waters in parts of the North Atlantic, with evidence of warming in bottom waters generally lacking. At the same time, although evidence of the terrestrial Dan-C2 event has been discovered, the terrestrial records still have significant deficiencies in terms of quantification, chronology, and continuity compared with the marine records, which makes it difficult to conduct in-depth and effective comparisons between the terrestrial and marine records; therefore, the global significance of the Dan-C2 event is questioned. \mathrm{②} The trigger mechanism is controversial; the high-precision chronological frame shows that the Dan-C2 event occurred at the eccentricity maximum, indicating that the orbital cycle had a certain influence on the event. Simultaneously, the temporal coincidence of the Dan-C2 event with the last phase of the eruption of the Deccan Traps volcanism implies that greenhouse gas emissions from volcanic activity may have contributed to warming during the Dan-C2; however, the relative magnitudes of both contributions to the event is difficult to assess. Future research should focus on the following: \mathrm{①} Exploring the variability of the Dan-C2 event records in different areas and revealing the reasons for the absence of deep-ocean water records. \mathrm{②} Establishing more reliable terrestrial records and further exploring the global significance of the Dan-C2 event and its triggering mechanism.