Abstract Carbonate weathering carbon‐sink (CWCS) is a critical yet inaccurately quantified component of terrestrial carbon sequestration. However, the mechanisms through which climate change and vegetation dynamics drive the spatial heterogeneity of CWCS remain unclear. We integrated multi‐source data to identify altitude thresholds and nonlinear response characteristics of CWCS driven by climatic and vegetation globally. Our findings show that global carbonate weathering sequestered 127.60 ± 7.70 Tg C yr−1 from 1950 to 2014, equivalent to 3.65% of global forest carbon sink. We identified a dichotomous pattern in CWCS at an altitude threshold of 3,000 m: rates decreased below but increased significantly above this elevation. This altitude threshold marks a fundamental shift in climate sensitivity and driving mechanisms, meaning that warming inhibits carbonate weathering in warm lowlands, while high‐altitude cold regions accelerate carbonate weathering through enhanced glacial snowmelt (percent contribution: 20.71%–38.96%) and vegetation–carbon dioxide feedback (NDVI threshold: 0.33–0.67). By 2100, global CWCS is projected to increase by 14.51%–24.90% compared to historical period (1950–2014). High‐altitude cold regions are projected to emerge as pivotal growth areas for CWCS in the future (2015–2100), contributing 45.02%–59.50% of newly added CWCS, despite accounting for only 28.41% of carbonate areas. Our results demonstrate that climate warming has transformed cold high‐altitude regions into indispensable engines for enhancing terrestrial carbon sink.

Abstract. This paper describes Global Change Analysis Model-China version 8 (GCAM-China-v8), an open-source integrated assessment model that represents interactions among energy, economic, and water systems within a globally consistent framework, with explicit subnational representation for China. GCAM-China-v8 builds on the GCAM and represents the world as 31 geopolitical regions outside China, while disaggregating China into 31 province-level regions to capture regional heterogeneity. GCAM-China-v8 can be used to explore how changes in socioeconomic drivers, technological progress, and policy assumptions affect energy and water demand and production at the subnational level in China, while maintaining consistency with national and international boundary conditions. This paper documents the model structure and data inputs, with particular emphasis on the methodological updates introduced in GCAM-China-v8, including enhanced sectoral and temporal representations. To demonstrate the capabilities of the updated model, we apply GCAM-China-v8 to two illustrative scenarios with contrasting assumptions about future socioeconomic development and energy system transformation. This paper provides a transparent and extensible modeling framework for future research on China’s long-term energy and climate transitions. It also contributes to the broader Integrated Assessment Models (IAMs) community by advancing national-scale model development within an open and consistent framework.

Global change is accelerating the chemical weathering of silicate rocks and the associated phosphorus release. However, the effects of phosphorus release on the global patterns of plant phosphorus limitation remain unclear. Here, we show that approximately 47% of the exposed areas in global silicate rocks are subject to phosphorus limitation of vegetation growth, as estimated using the ratio of leaf nitrogen to phosphorus resorption efficiency. Phosphorus-limited areas are projected to expand markedly with global warming, and the proportion may reach 54 - 59% according to two model scenarios (the shared socioeconomic pathways SSP2-4.5 and SSP5-8.5). Nevertheless, phosphorus release from accelerated chemical weathering of silicate rocks mitigates this limitation, with a relative contribution of approximately 15.5%. This work highlights the implications of accelerated chemical weathering of silicate rocks and its resulting phosphorus release for the global patterns of phosphorus limitation, providing a scientific foundation for phosphorus management strategies.

Wind and solar power are central to Chinau2019s carbon neutrality strategy and energy system transformation. This review adopts a system-oriented perspective to examine the future development of wind, photovoltaic (PV), and concentrated solar power (CSP), situating technological progress within a broader framework that includes forecasting approaches, power system flexibility, energy storage integration, and sectoral coupling. It summarizes the spatial potential and projected capacity trajectories under carbon neutrality goals, with estimates suggesting a combined capacity of 5,496 to 7,662 GW of wind and solar power by 2060, constituting more than 83% of Chinau2019s total installed power capacity. While notable progress has been made in technological maturity and the reduction of power generation costs, supported by robust domestic supply chains, persistent challenges remain across technical and systemic dimensions, including limited generation efficiency, the high cost of supporting energy storage technologies, and constraints on grid flexibility and policy coordination. This review further proposes a strategic roadmap for sustainable development, emphasizing the integrated deployment of wind and solar as the dominant sources of power generation.

Large-scale rural depopulation has altered the rural environment and reshaped the distribution pattern of species. However, the impact of rural depopulation on biodiversity is unclear. Based on plant species richness data, we used random forest model (RFM) and generalized additive model (GAM) to explore the impact of rural depopulation on plant diversity. The results showed that a 1.82 % decrease in human pressure in rural depopulation areas in China promoted vegetation restoration and increased plant diversity. Plant diversity in rural decreased by 2.25 % on average, while it increased by 3.75 % in rural areas that experienced depopulation. Plant diversity was 1.48 times greater in the severely depopulated rural areas than in the slightly depopulated areas. When the total population reaches around 1.33 billion, the plant diversity affected by population changes will reach a threshold. This research helps understand the potential positive impacts of rural depopulation on environmental restoration and plant diversity increase.

In this study, the characteristics of rural domestic wastewater discharge in the Yangtze River Basin, China, are analysed via geographic information visualization, pollutant load assessment, and correlation analysis. Through the use of a geographic information visualization system, this study intuitively presents the characteristics of rural domestic wastewater discharge in the Yangtze River Basin. In pollutant load assessment, the pressure caused by rural domestic wastewater discharge on maintaining the target water quality standards in the tributaries and main stream of the Yangtze River is comprehensively analysed. Correlation analysis reveals the social and natural factors influencing the levels of rural domestic wastewater discharge. The findings indicate that the average discharge level of rural domestic wastewater in the Yangtze River Basin remains low, with an average water discharge level of 39.24 L/(capita·day), a chemical oxygen demand (COD) of 27.50 mg/(capita·day), an ammonia nitrogen (NH3-N) content of 1.53 mg/(capita·day), a total nitrogen (TN) amount of 2.74 mg/(capita·day), and a total phosphorus (TP) content of 0.22 mg/(capita·day). Based on the current levels of rural domestic wastewater discharge and the concentrations of the above substances in the natural environment, the impact of rural domestic wastewater discharge on maintaining water quality functions in the tributaries and main stream of the Yangtze River can be considered negligible, although regional differences exist. Discharge levels are significantly influenced by various social factors, including educational level, per capita disposable income, and consumption expenditures, as well as natural factors such as average annual temperature, average annual humidity, and average annual rainfall. Overall, this study provides reference data for the analysis and management of rural domestic wastewater discharge in both similar regions in China and globally.

The karst geological carbon sink, formed through the chemical weathering of carbonate rocks, is an important part of the global terrestrial carbon sink. It has substantial potential and plays a crucial role in the global carbon cycle and regional carbon neutrality efforts. The fifth (AR5) and sixth (AR6) assessment reports of the Intergovernmental Panel on Climate Change (IPCC) have clearly affirmed the existence of geological carbon sinks associated with the chemical weathering of carbonate rocks, stating that carbon capture and geological storage are key mitigation schemes. However, numerous studies have shown that exogenous acids are widely involved during the chemical weathering of rocks, adding complexity to the carbon sequestration process and its driving mechanisms. This increases the uncertainty in assessing the carbon sequestration potential. Therefore, a key task is to accurately estimate the geological carbon sinks generated by the chemical weathering of carbonate rocks to resolve the problem of the global carbon sink loss, balancing the carbon budget, and achieving carbon neutrality. In this review, we examine assessments of the carbonate rocks chemical weathering carbon sink influenced by exogenous acids, focusing on the principles, frameworks and methodologies of carbon sink estimation. We also highlight recent advancements, key influencing factors, and underlying driving mechanisms. Looking ahead, we highlight key challenges in enhancing the accuracy and precision of carbonate rocks chemical weathering carbon sink assessments under the influence of exogenous acids. Addressing these issues will support more informed policy decisions on pathways to global carbon neutrality.

Seismic peak ground acceleration (PGA) is a key indicator to characterize the strength of seismic effects, which affects the rate of chemical weathering of carbonate rocks and the ability to capture CO2. However, the response mechanism and process of Carbonate rock weathering Carbon Sink (CCS) to PGA are not clear. To this end, this paper clarifies the spatial and temporal patterns of CCS in China and reveals their response to PGA based on PGA, climate, lithology and other datas, combined with methods such as the random forest model and maximal potential dissolution model. The results showed that the CCS Flux(CCSF) was 5.32 t C km-2 yr-1 and the Full CCS (FCCS) was 1346 x 104 t C yr-1, which was influenced by PGA, with the flux being the largest at 0.05 g PGA (5.38 t C km-2 yr-1), mainly in the south-western part of the country where hydrothermal conditions are favourable. Meanwhile, the response of CCS to PGA was affected by latitude and altitude divergence. CCS at the same latitude showed a fluctuating downward trend with the enhancement of PGA. Two trends of CCS and PGA at the same altitude appeared, one was that CCS increased with the enhancement of PGA when the altitude was less than 2500 m as well as 4500-6500 m, and the other was that CCS decreased with the enhancement of PGA when the altitude was 2500-4500 m. At the same PGA, CCS decreased with increasing latitude and elevation, respectively. This may be due to the fact that higher altitude and latitude are associated with lower temperatures, which affects the rate of chemical weathering of carbonate rocks, and hence CCS. The aim of this paper is to understand the response relationship between CCS and PGA, which helps to reveal how geologic activities affect the carbon cycle. The results of the study bridge the gap between tectonic geology and CCS systematic research to a certain extent, and promote the integration of the disciplines. This is of great significance for assessing the potential impact of natural disasters such as earthquakes on carbon sinks.

Ecological connectivity in landscapes is crucial for plant diversity conservation. The barrier risk to ecological connectivity represents the risk to ecological connectivity loss or weakening, resulting from the barrier to biological information exchange among habitats. Therefore, clarifying the barrier risk to the ecological connectivity of plant diversity in space can reveal the spatial impacts of reduced ecological connectivity on plant diversity. This study analyzed effects of karst peak, river network, arable land, and impervious surface on plant diversity in karst natural, countryside, urban, and island landscapes in Guizhou Province with fragile environment. Then, we calculated the barrier distance of ecological connectivity to reveal the barrier risk to the ecological connectivity of plant diversity in space. The results showed that karst peak was the source of high plant diversity, and plant diversity could diffuse about 400 m around karst peaks. River network and arable land enhanced the connectivity among karst peaks to maintain plant diversity, and the effect on enhancing the connectivity was about 300 m and 450 m, respectively, while the weakening effect of impervious surface on connectivity was about 350 m. Based on the distance for plant diversity diffusing around karst peaks, the barrier distance of ecological connectivity was determined by the combination type of river network, arable land and impervious surface in landscapes. From low to high, the barrier risk to the ecological connectivity of plant diversity was about 1,110 m in the combination of river network and arable land, about 790 m in the combination of river network, arable land and impervious surface, about 520 min the combination of arable land and impervious surface, about 400 m in the combination of river network and impervious surface. Our findings clarify the barrier risk to the ecological connectivity of plant diversity in space, and provide a scientific basis for plant diversity conservation from the perspective of ecological connectivity.

Carbonate rock chemical weathering carbon sinks reduce the rate of increase of the atmospheric CO2 concentration and global warming. However, uncertainty still exists in the estimation results of carbonate rock chemical weathering carbon sink fluxes (CCSF), and the contributions of climate change and ecological restoration to the CCSF are not clear. To this end, we compiled published site data on ion concentrations in different watersheds in China and used a classical thermodynamic dissolution model to reassess the potential and spatial and temporal patterns of the CCSF in China from 1991 to 2020. We quantified the contributions of temperature (MAT), precipitation (MAP), evapotranspiration (ET), soil water (SM), and the normalized difference vegetation index (NDVI) to the CCSF. The results revealed that (1) China's CCSF was 22.76 t CO2 km-2 yr-1, which was higher than the global average (15.771CO2 km-2 yr-1). The total carbonate rock chemical weathering carbon sink (CCS) was 4772.67x104 t CO2, contributing 14.91% of the global CCS through a carbonate rock area of 252.98x104 km-2. (2) China's CCSF decreased gradually from southeast to northwest, with values of 33.14, 12.93, and 7.27 t CO2 km-2 yr-1 in the southern karst, Qinghai-Tibetan karst, and northern karst regions, respectively. (3) The overall CCSF in China exhibited an increasing trend from 1991 to 2020, with a rate of increase of 0.16 t CO2 km-2 yr-1. (4) The contributions of the MAP, MAT, ET, SM, and NDVI to the CCSF were 63.3%, 3.02%, 27.5%, 3.1%, and 3.05%, respectively. Among them, the increase in precipitation was the main contributor to the increase in the CCSF in China over the last 30 years, while the enhancement of ET offset part of the positive contribution of the increase in precipitation to the CCSF. In conclusion, the results of this study provide a systematic quantification of the magnitude, the patterns, and the influencing factors of CCS over a long time series in China. The results are of great significance and provide a reference for the diagnosis and gap analysis of the national and global carbon neutrality capacities.

The control of rocky desertification is the largest ecological restoration project in southwestern China, but its impact on the carbon sequestration capacity of karst ecosystems is not clear. Therefore, in this paper selects typical subtropical karst areas in Guangxi are selected as the research object, the carbon sequestration potential of the terrestrial ecosystems are quantified, including karst inorganic carbon sinks, and the response of the terrestrial ecosystem carbon sink to rocky desertification restorationis discussed. The results show that (1) the karst inorganic carbon sink flux (CCSF) is 42.75 t CO2/km2/yr, with a total CCS of 491.12 x 104 t CO2, accounting for only 2.5 % of the country's land area and contributing 7.6 % of the karst inorganic carbon sink. (2) The flux of the vegetation organic carbon sink is 380.44 t CO2/km2/yr, and the total amount is 4403.55 x 104 t CO2/yr., Overall, the spatial distribution exhibits a pattern of high in the northwest and low in the northeast. (3) With decreasing rocky desertification area, the magnitude of the terrestrial ecosystem carbon sink has exhibited a corresponding increasing trend. In particular, during 2010-2020, the rocky desertification area decreased by about 0.868 x 104 km2, and the terrestrial ecosystem carbon sink increased by 114.04 t CO2/km2/yr. This article provides a systematic spatial diagnosis of the carbon sequestration potential of terrestrial ecosystems, including karst inorganic carbon sinks, in the karst areas of Guangxi, and reveals their responses to the restoration of karst rocky desertification. This work has strong reference value and significance for the diagnosis and analysis of the carbon neutrality capacity at the national and global levels.

The importance of carbonate weathering carbon sinks (CCSs) is almost equal to that of vegetation photosynthesis in the global carbon cycle. However, CCSs have become controversial in formulating carbon neutral policies to deal with global climate problems in various countries, since the carbonate dissolution is reversible. In order to address these controversies, we reviewed recent advances in understanding CCSs and examined the outstanding controversies surrounding them. We have analyzed the five controversies, revealing the existence of CCSs, quantifying their magnitude, clarifying their spatiotemporal pattern, and documenting how they have increased and how they evolved under the background of global change. By addressing these five controversies, we help to bring clarity to the role of CCSs in the carbon cycle of global terrestrial ecosystems.

Soil biodiversity (SB) is experiencing significant changes worldwide, yet its responses to climate and land use changes remain unclear. In light of this, we combined multiple environmental factors to construct a global SB dataset with a spatial resolution of 0.25 degrees degrees x 0.25 degrees degrees from 2000 to 2019. We determined that the global mean SB value was 0.66 during 2000-2019, and it slowly increased at a rate of 6.24 x 10-4/yr.-4 /yr. The highest SB value (1.20) occurred within the Amazon Plain. Among the climate factors, temperature (T) was found to be responsible for the majority of the SB changes, accounting for approximately 40% of them. Compared to the results of other studies, our findings indicated that the SB increased across all types of land use and that urbanization had a positive impact on the increase in the SB. However, the most significant increase occurred in the pasture/range land. Precipitation (P) had similar effects on the SB in the pasture/range land and unmanaged grass/shrubland, while the areas with sparse or no vegetation experienced significant variations in temperature. These findings provide additional insights into the global pattern of SB and highlight the role of climate and land use changes in driving global and regional changes in SB.

Dryness stress can limit vegetation growth, and the cooling potential of vegetation will also be strongly influ-enced. However, it is still unclear how dryness stress feedback weakens the sustainability of vegetation-based cooling. Based on the long-time series of multi-source remote sensing product data for the period 2001-2020, the relative contribution rate, and the method of decoupling and boxing, we determined that greening will likely mitigate global warming by 0.065 +/- 0.009 degrees C/a, but nearly 47 % of the area is unsustainable. This phenomenon is strongly related to dryness stress. The restricted area of soil moisture (SM: 68.35 %) to vegetation is larger than that of the atmospheric vapor pressure deficit (VPD: 34.19 %). With the decrease in SM, vegetation will decrease by an average of 14.9 %, and with the increase in VPD, vegetation will decrease by 3.8 %. With the continuous increase in the dryness stress area, the sustainability of the vegetation cooling effect will be threatened in an area of about 21.03 million km2, which is equivalent to the area of North America. Specifically, we found that with the decrease in SM and the increase in VPD, the contribution of vegetation to the cooling effect has been weakened by 10.8 %. This conclusion confirms that dryness stress will threaten the sustainability of vegetation -based climate cooling and provides further insight into the effect of dryness stress on vegetation cooling.

China is experiencing large-scale rural-urban migration and rapid urbanization, which have had significant impact on terrestrial carbon sink. However, the impact of rural-urban migration and its accompanying urban expansion on the carbon sink is unclear. Based on multisource remote sensing product data for 2000-2020, the soil microbial respiration equation, relative contribution rate, and threshold analysis, we explored the impact of rural depopulation on the carbon sink and its threshold. The results revealed that the proportion of the rural population in China decreased from 63.91 % in 2000 to 36.11 % in 2020. Human pressure decreased by 1.82% in rural depopulation areas, which promoted vegetation restoration in rural areas (+8.45 %) and increased the carbon sink capacity. The net primary productivity (NPP) and net ecosystem productivity (NEP) of the vegetation in the rural areas increased at rates of 2.95 g C m- 2 yr- 1 and 2.44 g C m- 2 yr- 1. Strong rural depopulation enhanced the carbon sequestration potential, and the NEP was 1.5 times higher in areas with sharp rural depopulation than in areas with mild rural depopulation. In addition, the rural depopulation was accompanied by urban expansion, and there was a positive correlation between the comprehensive urbanization level (CUL) and NEP in 75.29% of urban areas. In the urban areas, the vegetation index increased by 88.42%, and the urban green space partially compensated for the loss of carbon sink caused by urban expansion, with a growth rate of 4.96 g C m- 2 yr- 1. Changes in rural population have a nonlinear impact on the NEP. When the rural population exceeds 545.686 people/km2, an increase in the rural population will have a positive impact on the NEP. Our research shows that rural depopulation offers a potential opportunity to restore natural ecosystems and thus increase the carbon sequestration capacity.

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The human-water relationship (HWR) has shifted from the simple utilization of water resources to a complex spatial redistribution process through powerful human activities, such as water conservancy projects and policies. Water conservancy projects have changed the HWR; however, it is still unclear how related policies, such as the ecological civilization policy recently advocated by the Chinese government, affect the HWR. Here, a nearly 600-year typical Tunpu village named Baojia Tun was taken as the study area. Based on an improved water balance formula and a new technology known as remote sensing hydrological station (RSHS), the water cycle process over nearly 600 years in the typical Tunpu village named Baojia Tun and its basin was reconstructed, and the long-term evolution of the HWR over different space and time spans was revealed. The results show that (1) the HWR developed from an initial resource-rich balanced stage to an extensive-development unbalanced stage and finally transformed into a rebalancing stage; the four stages of the HWR are predevelopment, take-off, ac-celeration, and rebalancing. (2) At the village scale, due to the suitable geographical conditions and cultural value, the composition of water use units in the water cycle process of Baojia Tun has generally remained stable from the Ming Dynasty to modern times. (3) At the basin scale, due to the increased runoff caused by land use/cover change being more significant than the decreased runoff caused by irrigation water intake, the trend of runoff shifted from slowly decreasing to accelerated increases, with the change rate of runoff increasing from -6.21 x 10(4) m(3)center dot a(-1) in the Ming Dynasty (1470-1636) to 48.78 x 104 m(3)center dot a(-1) in the China stage (1949-2020). (4) The synchronous promotion of socioeconomic development and the ecological civilization policy has realized the unity of socioeconomic and ecological benefits, making the HWR exhibit a good sign of rebalancing. This research reveals that the positive effect of ecological civilization policy on the HWR can eliminate the unfavourable factors in the previous development model and adjust it to a sustainable development model, providing significant enlightenment for long-term planning and policy formulation for sustainable high-quality develop-ment in other countries or regions.

China is the country with the largest area and widest distribution of carbonate karst, with a population of approximately 200 million and an economic scale of approximately 10% of the country. In particular, the southwest region centered in Guizhou, located at the upper reaches of the Yangtze and Pearl Rivers, is an economically underdeveloped but critical ecological security barrier for the country. Karst landforms are important topological features. Scientific diagnosis of the health of its ecosystem is not only essential for ecological restoration and sustainable development but is also the basic premise for formulating response plans. Although a significant amount of research has been carried out in the past, a lack of systematic and holistic understanding still exists. Based on previous studies, in this paper, we further summarize the evolution and development of karst landforms into six stages: diagenetic, continental, mountain-forming, cluster, forest-forming, and primitive stages. On this basis, we also systematically summarize and detail five aspects: The calculation of weathering and soil-forming rate of carbonate rocks, diagnosis of soil water, evaluation of soil and water loss, interpretation and evolution of rocky desertification, and scientific measurement of ecosystem services. Despite the different research methods of different scholars in different times, the results are very different. However, after comprehensive consideration of the existing research results and the advantages and disadvantages of their application methods, the following conclusions were made. (1) Although the chemical weathering of carbonate rocks is very fast (30-130 mm ka(-1)), their soil formation rate is extremely slow due to their low content of acid-insoluble substances (within 5%), generally between 5 and 50 t km(-2) a(-1). (2) The soil is small and the distribution discontinuous, but the soil water content is relatively high, ranging from 0.2 to 0.4 m(3) m(-3). This may be related to the catchment effect of surrounding bedrock, and it will be dry in the future. (3) The modulus of soil erosion is low, generally between 2 and 200 t km(-2) a(-1). However, due to steep slope, heavy rainfall, and abrupt contact with rock and soil, the risk of soil erosion is very high, and there is a certain proportion of underground leakage. (4) The evolution of rocky desertification can be divided into three classic types, namely univariant, progressive, and retro-variant, but the method of rocky desertification resolution through decision tree and human-computer interaction is relatively efficient and accurate. (5) The evaluation model of karst ecosystem service function should be based on the soil formation rate to correct the water and soil conservation function and the climate adjustment function based on the karst geological carbon sink. At present, the indicators, methods, and models for diagnosing the health of the karst ecosystem must be improved and innovated to fully reflect the particularity of the karst region and the matching of the model methods, to improve the spatial and temporal resolution of the monitoring data (especially to establish a coupling model of the karst social-ecosystem), to accurately depict the response process of the karst ecosystem to climate change and human activities, and to improve the accuracy and predictability of the diagnostic model. In short, in this paper, we systematically summarize and detail the methods and major progress in diagnosing the health and sustainability of China's karst ecosystem and further propose the future research direction and breakthrough focus from the perspective of "rock soil water stone life", with a view to providing scientific and technological support for maintaining the ecological security and sustainable development of karst areas.