The article proposes the main scientific issues associated with achieving carbon neutrality goal. The scientific understanding needed for achieving carbon neutrality goal and its role in supporting the achievement of this goal are comprehensively discussed focusing on three aspects of natural changes in the Earth system, the relationships between carbon neutrality and the natural Earth system, as well as between carbon neutrality and human activities. It is indicated specifically that the scientific issues related to natural changes in the Earth system include the understanding of carbon cycle in the Earth natural system, the role played by natural processes in climate warming, and paleoclimate change. The scientific issues related to the relationship between carbon neutrality and the Earth natural system include the impact of carbon neutrality on the Earth natural system, and sensitivities of climate warming to greenhouse gas radiative forcing. The scientific issues related to the relationship between carbon neutrality and human activities include interactions of the Earth natural system with socio-economic system, local-scale atmospheric variations associated with clean energy development and its impacts, as well as geoengineering and its influences on the Earth natural system. It is pointed out that an in-depth understanding of these issues will offer an essential scientific basis for adapting and mitigating climate change reasonably and effectively, which can provide an important scientific support in achieving the goal of carbon neutrality.

Climate change is a serious challenge to natural ecology and human society. As an important tool for addressing climate change, climate models provide important support for understanding the mechanism of the past climate system, climate services and projections of future global change scenarios. However, problems in process representation, subgrid parameterization and spatial resolution of climate models have severely limited their simulation and prediction capabilities. With the development of economy and society, artificial intelligence (AI) technology has been widely used, and its advantages of integrating multi-source data, identifying potential information, and learning from existing “experience” are expected to provide new assistance for climate research and application. Against this background, this paper firstly provides a concise review of the development of climate models, then combines the characteristics of AI on this basis to examine the application of AI in climate research and services, and analyzes the challenges faced at this stage. The results show that existing observational data and model outputs can provide a sufficient data base for AI applications, and AI can optimize and integrate climate models accordingly, thus improving the accuracy of climate simulation and prediction results. In the future, it is important to focus on the coupling of AI and climate models and to expand the application of AI in various areas of climate change, so as to more effectively address the challenges posed by global climate change.

Weather forecasting is closely related to the social economy and people’s lives. With the intensification of global warming, extreme weather events are widespread, frequent and intense, and traditional weather forecasting will face more significant challenges. Firstly, the relationship between climate change and extreme weather events is expounded in this paper, and then the impacts of global climate change on conventional and extreme weather forecast are analyzed, and it is found that climate change will increase the difficulty of extreme weather forecasting, and the role of improving the accuracy of extreme weather forecasting in disaster prevention and mitigation under the “new normal” is also emphasized and further analysis of climate warming will make weather forecasting face new challenges. On this basis, this paper further puts forward new trends of future weather forecast operational developments as well as countermeasures and suggestions to adapt to climate change, such as vigorously developing high-resolution and multi-circle nested numerical prediction models, in-depth research on the mechanism and predictability of extreme weather events in the context of climate change, developing the combination of dynamic-statistical model based on mechanism and big data analysis, artificial intelligence technology and new forecasting methods, and improving the scientific literacy and ability of forecasters.

The Asian Water Tower is the most important and vulnerable water tower in the world. Its most prominent feature is the glacier and snow processes. Climate change has led to a rapid reduction of solid water bodies such as glaciers and snow in the Asian Water Tower, while liquid water bodies such as lakes and rivers have significantly increased, resulting in an imbalance between solid and liquid phases. There is a spatial imbalance in the distribution of water resources, with an increase in water resources in the northern endorheic basins and a decrease in the southern exorheic basins. Glaciers are melting at an accelerated rate, with significant spatial differences between the southeast and northwest, showing severe glacial mass loss in the southeast and Tianshan regions, relatively minor losses in the northwest regions, and relative stability or advancement in the Pamir and West Kunlun regions. Snow cover and annual snow days have decreased, snowmelt is occurring earlier, and both maximum snow water equivalent and snowmelt are decreasing. In the future, research should be focused on the changes in glacier and snow processes in high-altitude areas, improving the spatiotemporal resolution of glacier and snow process models, strengthening research on future water resource changes under different scenarios, and proposing water security response strategies.

In the past 40 years, climate change has led to the warming and humidification of the Tibetan Plateau, which has had a significant impact on the geographical distribution and function of ecosystems of forests, shrubs, grasslands, wetlands, and deserts. The distribution range of shrubs, grasslands and wetlands is expanding, with the boundary moving westward and towards high-altitude areas. Under the influence of climate change, the productivity, carbon sequestration, and soil conservation capacity of the ecosystem on the Tibetan Plateau have improved, and changes in water conservation have shown significant special heterogeneity. The profound impact of climate change on phenology, plant growth rate, distribution range and species interactions of animals and plants, as well as biodiversity, requires further observation and research.

The “Beautiful Cryosphere” (BC) is the extension and application of the concept of a “Beautiful China” in the cryosphere. It is a synthesis of natural beauty, service beauty, and harmonious beauty, and a dialectical unity of benefits and harms. The concept of the BC is re-explained in the text by reviewing and re-interpreting the connotation of the BC, analyzing the relationship between the BC and “Beautiful China”. On this basis, the origin and development course of the BC are analyzed from the two main lines of the systematization of cryosphere science and the construction of a Beautiful China and its researches, from the discipline and social perspectives. The two levels of research content within the BC are further analyzed. Driven by advances in understanding, national needs, and scientific research projects over the past 20 years. The evolution of the BC research content includes three phases: an exploration stage from 2007 to 2015, the stage of expansion and summary between 2015 and 2020, and comprehensive deepening stage from 2020 to the present.

The impact of climate change on the industrial sector is gaining increasing attention. Both slow-onset and sudden climate factors have important impacts on the manufacturing, mining, and electricity industries. In the short term, the industrial sector mainly engages in passive adaptation under the influence of climate factors, while in the long term, it can engage in proactive adaptation when anticipating climate change and its potential consequences. Case studies and questionnaire surveys are important approaches to understanding and analyzing the adaptive behavior of individual enterprises, while various econometric models and integrated models still focus on assessing the impact of climate change on industrial output, exports and other aspects, lacking evaluation and analysis of the climate adaptation behavior of the industrial sector. The challenges of adapting to climate change involve both research and practice. In terms of research, the definition of climate adaptation is controversial, and there exists a lack of exploration regarding the effectiveness of adaptation, maladaptation, and adaptive limits. In practice, cost and decision-making barriers are the main challenges. In the future, in order to assist the industrial sector in better adapting to climate change, it is important to conduct more quantitative analyses, link the impacts of climate change on industry with adaptation strategies, consider the heterogeneity of regions, industries, and enterprises, construct models and evaluation systems to explore the complex underlying mechanisms of industrial climate adaptation.

The response of cryospheric hydrological processes to climate change, and its impacts has become a key issue in global change research. On a global scale, the mass loss of glaciers (i.e., the amount of meltwater from glaciers) has shown an accelerating trend over the past 20 years, ranging from (48±16) to (57.6±13) Gt/(10 a), while significant regional differences exist. At the watershed scale, the response of glacier meltwater to climate change varies among different watersheds, primarily depending on the size of the glaciers within each watershed and the compositional characteristics of glaciers of varying sizes. Although there are still differences in understanding the future trends of glacier meltwater across various glacier regions, particularly regarding the timing of critical inflection points, there is a consensus on the overall pattern of spatial changes in glacier meltwater. The future trend in global glacier meltwater is expected to be controlled by the rate of change in ice sheets and large glaciers at high latitudes. Global warming has led to significant changes in the intra-annual distribution of runoff during the snowmelt period, with a notable advance in the timing of snowmelt in most watersheds by up to 20 days. Additionally, early snowmelt runoff has significantly increased, with peak flow occurring earlier. It is projected that an increase in the rain-to-snow ratio in the future will lead to a reduction in snowpack storage, while simultaneously increasing sublimation, further advancing the timing of snowmelt runoff and reducing its contribution to watershed runoff. Climate change affects permafrost hydrological processes in several ways, including changes in the hydrological effects of the underlying surface, the runoff regulation function of the active layer, and variations in the supra-permafrost water. In terms of the hydrological effects of the underlying surface, enhanced freeze-thaw cycles, the expansion of thermokarst, and the deepening of the active layer directly impact surface runoff generation and flow processes, thereby affecting the intra-annual distribution of surface runoff. Regarding the runoff regulation function of the active layer, changes in the active layer not only influence surface runoff processes but also affect vertical and horizontal subsurface flow within the active layer, as well as the recharge and runoff generation capacity of the supra-permafrost water. The most important aspect is that the freeze-thaw dynamic and depth variation of the active layer play a role in regulating hydrological processes both within the year and over the long term. In terms of supra-permafrost water changes, various studies have shown that permafrost degradation has already impacted subsurface runoff to some extent, with the most significant effect being the direct contribution of permafrost degradation to river flow. In some watersheds, this contribution even reaches a substantial magnitude. The role of cryosphere hydrology at the watershed scale mainly manifests in three aspects: water source conservation, runoff replenishment, and hydrological regulation. Climate change has led to significant changes in the elements of the cryosphere, which in turn have altered the watershed functions of cryosphere hydrology. However, these changes vary greatly across different watersheds.

Climate change has led to rapid cryosphere changes in the Qinghai-Xizang Plateau, resulting in the increasing of the scale and frequency of cryosphere disasters. Consequently, cryosphere changes impose considerable threaten to the engineering safety, impacting the regional sustainable development and people’s well-being in the Qinghai-Xizang Plateau. This paper reviews the challenges faced by engineering in the cryosphere regions of Qinghai-Xizang Plateau, and expounds the cryosphere changes in recent years and its future change trends. From the perspective of the types of cryosphere disasters and the observed influence of cryosphere disasters on engineering, the influence of cryosphere disasters caused by cryosphere changes on engineering design and safe operation, as well as the economic cost of engineering construction and maintenance are discussed. The coping strategies to mitigate the cryosphere changes and disasters under climate change are put forward, and the coping strategies and technical measures of engineering are discussed.

The cryosphere human geography and environment is a discipline to study geographical distribution pattern and evolution law of human activities (population, livelihood, culture, economy, politics, etc.) in the cryosphere, which is closely related to cryosphere science, climate change science, environmental science, sociology and other disciplines. This discipline mainly focuses on human activities in the cryosphere region, how humans adapt to the cryosphere environment, and the comprehensive impact of these environmental changes on human society. The results show that: (1) During 1970-2024, the keyword of indigenous people have the highest frequency and the highest correlation with other keywords, followed by sustainable development, culture, climate change adaptation, community and health. These keywords have a prominent position and are the focuses and hot spots of the research on the human geographical environment of the cryosphere. (2) Keyword clustering forms the 10 most representative clusters of “climate change adaptation, politics, sustainable development, indigenous people, channel, health, food security, resources, culture and tourism”. (3) From 1990 to 2020, the population in the Arctic showed a slight decrease trend, while the population in the Qinghai-Tibetan Plateau showed an increase trend. Due to the restriction of the cryosphere environment, the inter-regional population migration was weak. (4) The cryosphere culture is dominated by the traditional culture of sea hunting, hunting and nomadism; the religion is dominated by primitive polytheism; the ethnic and linguistic diversity; and it is significantly affected by modern lifestyle and climate change. (5) The Arctic cryosphere is dominated by traditional reindeer industry and fishing activities, while the exploitation of mineral, oil and gas resources is mainly operated by enterprises. At the same time, the loss of Arctic sea ice has boosted the import and export trade of Arctic countries. The regional economic structure of the Qinghai-Tibetan Plateau cryosphere is dominated by animal husbandry. (6) Opportunities and risks coexist in cryosphere tourism. As a result of climate warming, its tourism comfort is increasing, the accessibility of tourism around the Arctic is increasing, and the impact on snow and ice resources in middle and low latitudes is significant, which has affected the sustainability of ski tourism. (7) Accelerated melting of polar ice caps and sea ice has enhanced the availability of polar resources. As the interests of many countries are involved, all countries intend to expand their territory or sphere of influence and obtain more resources, which leads to the strengthening of the game between major powers. The geopolitical problems of the middle and low latitudes cryosphere mainly focus on “water conflict”. In view of the significant impact of climate change on the human and geographical environment of the cryosphere, more attention should be paid to three issues in the future: the improvement of the livelihood and welfare level of the indigenous peoples in the cryosphere, the autonomy of the indigenous people in the cryosphere, and the sustainable development goals and realization paths of the polar regions.

This paper systematically reviews major extreme weather and climate events in China’s regions under the intensified global warming background from 2010 to 2023. It focuses on analyzing the characteristics and socio-economic impacts of these events and further summarizes the latest progress in attribution research on these occurrences. Among the annual top ten significant weather and climate events in China from 2010 to 2023, extreme precipitation and flood events, along with typhoons, accounted for the highest proportion at 27% and 15%, respectively. Extreme heat, drought, cold-related low-temperature and snowfall events, as well as pollution events associated with haze and dust, each accounted for 11%-12%, while severe convective weather and other meteorological events accounted for 7% and 6%, respectively. With the intensification of global warming, the frequency and intensity of extreme heat, extreme precipitation, and drought events in China have significantly increased. Trend attribution of extreme events focuses on the impact of climate change on their long-term trends. The increase in extreme heat and drought events is mainly attributed to anthropogenic forcing, while extreme precipitation, drought, wildfires, and other extreme events are also closely linked to human-induced warming. Human activities, particularly greenhouse gas emissions, are the primary drivers of the long-term changes in extreme events in China. Event attribution research focuses on changes in the probability and intensity of extreme events themselves. Studies based on circulation analog methods, atmospheric models, and storyline approaches indicate that human activities have significantly increased the intensity and frequency of extreme heat, drought, wildfire events, and compound hot-dry events, while slightly reducing the probability and intensity of cold events. The impact on precipitation events varies by event type, but most studies suggest that human activities have heightened the risk of extreme precipitation events. Despite significant progress in the attribution of extreme events in recent years, research gaps remain in understanding events like severe typhoons, severe convective weather, and other types of compound extreme events. Additionally, challenges persist due to insufficient observational data and the lag in climate model development. Establishing a real-time detection and attribution system will provide scientific guidance for the formulation and implementation of disaster prevention and mitigation policies, holding great significance.

Severe air pollution events by fine particulate matter (PM_2.5) and ozone (O₃) are the target of air pollution control in China. This paper reviews the research progress on the impacts of climate change on severe pollution events of PM_2.5 and O₃ in China in recent years. The results show that severe PM_2.5 pollution mainly occurs under stagnant weather conditions, while severe O₃ pollution mainly occurs under conditions of high temperature and low humidity. Climate change (including both anthropogenic global warming and the natural variability in the climate system) affects the local meteorological conditions that are conducive to severe pollution through changing large-scale circulation and regional circulation pattern. At present, the research on the impacts of climate change on severe PM_2.5 pollution is quite advanced, with the capability of identifying the impacts of climate factors or global warming on typical severe pollution events or the long-term trends of such events. However, there are few studies on the impacts of climate change on severe ozone pollution.

There are usually two kinds of metrics being used to measure emissions, including Global Warming Potential (GWP) and Global Temperature Change Potential (GTP). These metrics are scientific basis for making emission policies and thus have important reference for policy makers in manufacturing and related economic fields. Meanwhile, it is significant to quantitatively understand the effects of emission and its reduction on the past and future climate change. How to accurately calculate and reasonably apply GWP and GTP to assess the impact of emission on global warming is an important scientific issue and a hot topic in climate change. Therefore, it has received extensive attention from the scientific community and related fields. IPCC AR5 and AR6 have set up special chapters for GWP and GTP to summarize and discuss the content of calculation methods and their application development. Based on the discussion of GWP and GTP in IPCC AR5 and AR6, this paper firstly summarizes the basic conceptions of emission metrics and their development in the past 30 years, then introduces the algorithms of common emission metrics of GWP and GTP in detail, finally gives the differences and applicability of the two metrics systematically. GTP is more closely related to global mean surface air temperature change, so it has potential advantages compared with GWP in evaluating the impact of greenhouse gases on surface air temperature. However, GTP also has some uncertainties, such as the influence of climate sensitivity factors, the heat exchange in the Earth system, and the selection of target time points. Then, the values of key emission indicators are summarized in the table for reference, including CO₂, CH₄, N₂O, HFC, CFC, PFC and aerosols. In addition, this paper also introduces some emerging emission metrics, such as Combined-GTP (CGTP) and GWP*. These new metrics are more precise, and more suitable for short-lived greenhouse gases.

This paper elaborates on the definition and origin of climate finance, analyzing its development, current status, challenges, and opportunities both domestically and internationally. Moreover, this paper explores how multilateral development banks are innovating in climate finance and discusses the lessons and value that can be learned from their approaches. Finally, the paper proposes seven recommendations to promote the future development of climate finance in China: improving the policy system of climate finance, establishing diversified financing channels, strengthening the construction of climate finance service systems, enhancing the application of digital technology, building a high-quality climate investment and finance project pool, exploring quantitative methods for climate finance, and intensifying international cooperation and exchanges.

As a major frontier scientific field in climate change research, climate change detection and attribution aim to reveal the causes of climate change and quantify the impact of external forcing on climate change. These issues are not only the core of scientific research on climate change, but also the hotspot and focus of the international negotiations on climate change. China started relatively late in the field of detection and attribution, but in the past decade, with the efforts of Chinese scientists, we have achieved a number of breakthroughs in the understanding of regional climate change and the attribution of extreme events in China, and made remarkable research progress in the field of detection and attribution of climate change in China. This review shows that since the middle of the 20th century, human activities, mainly greenhouse gas emissions, are the major driver of regional warming and changes in the frequency, intensity and duration of temperature extremes in China. Human activities have a clear influence on changes in extreme precipitation, and signals of human activity can also be found in changes in some types of drought. At century scale, anthropogenic signals can be detected in the change in both mean and extreme temperatures. For major high-impact extreme events, anthropogenic forcing increases the probability of hot extreme events and decreases the probability of cold extreme events. The attribution conclusions of human influence on heavy precipitation events, drought events and complex events have low consistency, and are affected by event definition and attribution methods, etc. It is still very difficult to assess the general conclusions on the extent of human activities’ influence on these events. In the future, it is necessary to strengthen the detection and attribution on changes in precipitation, drought, atmospheric circulation, compound events, etc., to understand and improve the reliability of extreme event attribution results.

From the perspective of the energy framework, related research on Earth’s energy budget, effective radiative forcing, climate feedback, and climate sensitivity is systematically reviewed. Since the 1980s, Earth’s energy budget has increased by 0.28-0.52 W/m², primarily due to a sustained reduction in reflected solar radiation at the top of atmosphere. This is a crucial factor driving global warming during this period. These changes in the energy balance are closely linked to anthropogenic forcings and their effects on the climate. The Intergovernmental Panel on Climate Change (IPCC) Sixth Assessment Report (AR6) indicates that during the period of 1750-2019, the best estimate of total anthropogenic effective radiative forcing is (2.72±0.76) W/m², which is projected to result in a global surface temperature increase of approximately 1.29 (1.00-1.65) ℃. Overall, climate feedback can offset the comprehensive disturbance caused by radiative forcing to the Earth system, helping to stabilize the climate state. The best estimate of net feedback provided by IPCC AR6 is -1.16 (-1.81--0.51) W/(m²·℃). To project future climate change, the IPCC AR6 provides best estimates for equilibrium climate sensitivity and transient climate response as 3.0℃ and 1.8℃, respectively, with very likely ranges of 2.0-5.0℃ and 1.2-2.4℃. Based on the forcing-feedback framework under the energy budget balance, the scientific community has clarified the impact of external forcings, such as anthropogenic and natural factors, on climate change by quantifying the Earth’s energy budget and its long-term changes, and by distinguishing between radiative forcing and climate feedback. Based on the best estimates of climate feedback parameters and climate sensitivity, the magnitude of the climate response to forcing can be quantified, enabling reasonable projections of the future climate.

In order to respond to climate change and to conduct systematic globalized observations of atmospheric constituents and their related physical and chemical properties, the Chinese government, in cooperation with the WMO and the United Nations Global Environment Facility (GEF), established the first global atmospheric baseline observatory (the Waliguan Baseline Observatory) in the Eurasian hinterland at Waliguan Mountain, Qinghai province, in September 1994, and has also conducted long-term observations of key atmospheric constituents, including greenhouse gases, aerosols, ozone, radiation, and acid rain, which are closely related to weather, climate, the environment and human health. After 30 years of construction and development, the Waliguan Baseline Observatory has accumulated a large amount of first-hand and globally representative atmospheric background observational data, which provide fundamental support for in-depth research, assessment and prediction of changes in atmospheric composition and their impacts on weather and climate changes, and also serve as an early warning and monitoring of future changes in atmospheric composition. This paper systematically reviews the Waliguan Baseline Observatory’s development history, major observing programs, and research results over the past 30 years. It also looks forward to future development direction and research focus.

Subalpine forests, playing an important role in maintaining biodiversity and regional water and carbon balance, are highly sensitive to global climate changes. In the context of global climate change, response and adaptation of subalpine forests are among the key scientific issues of terrestrial ecosystems. Tree growth is an important reflection of changes in forest ecosystems. This paper summarizes the diverse patterns of subalpine tree growth along altitudinal gradients, and sums up potential mechanisms underlying the different growth responses of subalpine trees, which included “temperature and precipitation effect hypothesis”, “carbon supply limitation hypothesis”, “carbon utilization limitation hypothesis” and “the influence of underground ecological processes”. Finally, the shorting-comings of these existing hypothesizes are discussed, the importance of hydraulics character of trees in regulating ecological processes is disclosed, and the future research directions are prospected.

The impacts of climate change on natural disasters are intensifying, giving rise to new characteristics and trends in disaster activities, and a significant increase in disaster risks. Disaster prevention and mitigation efforts now face unprecedented challenges. This paper examines the mechanisms and activity patterns of natural disasters under climate-driven factors, focusing on cross-sphere disaster characteristics and the spatiotemporal ocean-land linkages of disaster activities. It highlights the “new normal” and challenges of disaster risks in the context of climate change and evaluates the effectiveness and limitations of current disaster risk management strategies. To enhance the scientific and technological capabilities for disaster risk prevention, this paper proposes five key scientific questions: (1) The impacts of climate change on sphere processes and their disaster-inducing mechanisms; (2) Prediction and risk evolution of catastrophic events driven by extreme weather; (3) Mechanisms and risk assessments of major disasters on socio-economic systems; (4) AI-driven adaptive framework for dynamic disaster risk management; (5) Theoretical frameworks for building resilient societies to adapt to climate change.

Integrated Assessment Models (IAMs) have played a significant role in the global and national processes of addressing climate change, especially in all the assessment reports of the Intergovernmental Panel on Climate Change (IPCC), supporting the evaluation and formulation of global emission reduction targets. The development of IAMs themselves has gone through stages from highly synthesized models to large-scale complex models. With the CO₂ emissions of countries committed to carbon neutrality accounting for the majority of global CO₂ emissions, the research direction of IAMs also needs to undergo major adjustments, shifting from the original focus on assessing scenarios and pathways for temperature targets to more detailed studies of economic sectors, technologies, and related economic and ecological environmental factors, in order to support the understanding and formulation of the paths and policy measures for energy and economic transitions under the goal of carbon neutrality. The transition of IAMs research needs to be advanced as soon as possible and requires the participation of more academic research groups.

In presence of anthropogenic forcing, global climate has exhibited a long-term warming trend, superimposed by a quasi-periodic multidecadal oscillation of 60—70 years, which is strongly influenced by the Atlantic Meridional Overturning Circulation (AMOC). As a critical component of the global ocean circulation, AMOC governs the distribution of ocean heat and freshwater, thereby significantly impacting climate. This paper reviews the structure and variability of AMOC based on direct observation array and the observation proxy since the instrumental temperature, salinity and sea surface height are available. We show that the AMOC leads the global mean surface temperature by approximately 45°—90°, which is primarily driven by heat transport in the intermediate and deep ocean and its effect on the surface climate system’s energy balance modulated by external radiative forcing. We also address key challenges in understanding AMOC variability and its climatic implications: first, observations did not exhibit statistically significant AMOC trend, providing few supports to the AMOC slowdown shown in numerical models; second, external radiative forcing may alter the relationship between AMOC variability and global surface temperature through its impacts on the internal climate variability. Future research should focus on continuous, high-quality observations to enhance understanding of AMOC’s multidecadal variability and its climate impacts, for more accurate climate models and more effective climate change policies.

In this paper, the development process of the IPCC National Greenhouse Gas Inventory Guidelines is systematically reviewed, and the evolution characteristics of its four stages are summarized, namely, from the initial stage framework construction to the systematization and department improvement stage, and then to the stage of system upgrade based on scientific research breakthroughs, further, to refine and finalize the latest guidelines. Based on the Modalities, Procedures and Guidelines (MPGs) for the transparency framework for action and support referred to in Article 13 of the Paris Agreement, and using the 2006 IPCC National Greenhouse Gas Inventory Guidelines, the specification and requirements for the preparation of greenhouse gas inventories are systematically elaborated, the mandatory requirements (“shall”) and non-mandatory requirements (“should”, “may” and “encourage” ) in MPGs are compared and analyzed, and the institutional construction based on the design of “mandatory regulations plus flexibility mechanism” are revealed. Finally, it highlights the challenges China faces in transition from the 1996 Guidelines to the 2006 Guidelines while preparing the Biennial Transparency Report (BTR) and National Inventory Document (NID). It also proposes measures to address these issues and recommends accelerating the establishment of a greenhouse gas accounting and reporting system that meets the requirements of the MPGs with Chinese characteristics.

The current global average sea level rise is experiencing an acceleration. This study assesses the risk of permanent inundation in coastal China caused by sea-level rise under the extreme scenario of rapid ice sheet retreat. The bath-tub approach is employed to simulate the inundation extent due to future sea-level rise. Under the SSP1-2.6 and SSP5-8.5 scenarios, the newly added static permanent inundation area along the coast of China increases from 0.32%-2.29% in 2100 to 1.14%-6.33% in 2150. Existing coastal defenses can effectively cope with the process of gradual permanent inundation, with major risks lying in high-tide flooding and backwater effects caused by the rise in baseline water levels, as well as the amplification effect on the frequency of extreme coastal floods. It is necessary to promptly assess the capabilities of coastal defense levels and take corresponding measures, emphasizing the impact of amplification effects from extreme compound disasters. In the Black Swan scenario of ice sheet instability, the range of sea-level rise far exceeds coastal defense capabilities, leading to widespread static inundation. By 2300, the inundation areas will account for 6.26%-18.89% of coastal regions. The destabilization of polar ice sheets can lead to extremely high rates of sea-level rise, leaving a relatively short window for coastal adaptation measures, such as enhanced defenses, and increasing the risk of systemic failures. Coastal regions need to prioritize emerging risks under the Gray Rhino and Black Swan scenarios of sea-level rise to meet the demands of climate change adaptation planning and risk management decisions.

As agricultural production faces an increasing risk of climate change, there is an urgent need to strengthen adaptive capacity building in order to promote extensive agricultural adaptation actions. This paper synthesizes the progress of scientific understanding on agricultural adaptation to climate change and the scientific support on adaptation actions with literature review, and then summarizes the progress and shortcomings in the capacity building for agricultural adaptation to climate change according to the logical layers of efficient utilization of agro-climatic resources, agricultural disaster prevention and alleviation, ecological governance and climate risk management. Presently, the description on adaptive capacity building in the published literatures, reports, and policy documents is too general. This paper presents an effort on in-depth investigation how to increase agricultural adaptive capacity. The capacity building for efficient utilization of agro-climatic resources, agro-meteorological disaster reduction, ecological governance, and agricultural management is clarified as utilizing thermal climatic resources and water resources; lowering the climatic hazards, diminishing exposure, decreasing vulnerability of climate change-affected agricultural systems; increasing the agricultural ecosystem services of food production and supply, regulation, supporting, and cultural function; enhancing the research and development of agricultural adaptation technologies, innovating the financing mechanism, and improving policies and legislation, respectively. Finally, it proposes a series of recommendations for the enhancement of future agricultural adaptive capacity building, including the systematic evaluation of agricultural climate risk, identification of adaptation priorities, construction of agricultural adaptation technology system, formulation of agricultural adaptation plan, and raising public awareness regarding adaptation to climate change.