Research Progress in and Planning Strategies for Multi-scale Measurement of the Efficiency of Urban Blue-Green Infrastructure in Carbon Sink Enhancement and Emission Reduction

<sec><title>Objective</title> Ecosystem services are the link between ecosystems and social systems. While effectively coordinating regional ecological, social and economic needs and promoting carbon sequestration and emission reduction, ecosystem services can be transmitted to surrounding areas to boost regional ecological space optimization. Under the guidance of the carbon peaking and carbon neutrality goals, clarifying the positive impact of ecosystem services on net carbon sink efficiency in metropolitan areas and the spillover effect of ecosystem services can effectively contribute to regional ecosystem service enhancement, and realize efficient carbon sequestration and reduction in ecological space. </sec><sec><title>Methods</title> Supported by multi-source panel data spanning the period from 2010 to 2020, this research takes the Shanghai Metropolitan Area as the research object and divides the research area into 40 research units. Based on the multiple benefits of ecosystem services in synergistically promoting urban sink enhancement and emission reduction, this research constructs a net carbon sink efficiency indicator system. Then, utilizing the undesirable slacks-based measurement (SBM) model, the research evaluates the net carbon sink efficiency of each unit during the period from 2010 to 2020, and further explores the distributional characteristics and spatial-temporal changes of carbon sinks, carbon emissions, and net carbon sink efficiency from the geospatial perspective. In combination with the guiding content of spatial synergistic planning for the Shanghai Metropolitan Area, four important ecosystem services, namely water retention, water purification, soil retention and biodiversity maintenance, are quantitatively characterized with the InVEST model. Subsequently, based on the spatial decomposition effects (direct, indirect and total effects) obtained with spatial econometric model, the influencing mechanisms of ecosystem services and their interrelationship on the net carbon sink efficiency of 40 research units are analyzed. In addition, the spatial spillover effects of ecosystem services are innovatively revealed according to ecosystem service flow conduction mechanisms. </sec><sec><title>Results</title> Research results are summarized as follows. 1) During the 11 years from the 2010 to 2020, the growth of carbon dioxide emissions in the Shanghai Metropolitan Area gradually slowed down, while the net primary productivity of vegetation continued to increase, and the areas with high carbon emissions and high carbon sinks were partially overlapped; in addition, the net carbon sink efficiency of some core nodes, such as Shanghai City, maintained a steady improvement, effectively driving neighboring cities to reduce carbon emissions and increase carbon sinks; meanwhile, the areas with improved net carbon sink efficiency have some similar characteristics and can be divided into 2 types: areas with high production value, high carbon emissions, and high carbon sinks, and those with medium-high production value, low carbon emissions, and medium-high carbon sinks. 2) The four ecosystem services have significant spatial heterogeneity and relatively stable changes over the 11-year period, with the high values mainly distributed in the southwestern part of the area with high vegetation cover and the area around the Taihu Lake with concentrated water resources, while the low values mainly distributed in the concentrated urban construction areas and near the regional traffic arteries, and the total amount of the four ecosystem services has shown fluctuating characteristics. 3) Regarding the spatial decomposition effects of ecosystem services on net carbon sink efficiency, there are differences in the coefficients, directions and significance of the spatial effects of different ecosystem services. For the ecosystem service trade-off index and relationship index, the direct effects are significantly positive, while indirect effects significantly negative. </sec><sec><title>Conclusion</title> The research clarifies that water-related ecosystem services such as water retention and water purification services can significantly affect carbon reduction and sink enhancement in the Shanghai Metropolitan Area, and attention should be paid to water network system and its coupling effects with green and grey spaces, so as to further stimulate the ecological vitality of Jiangnan water vein. As there are differences in the spillover effects of different ecosystem services, it is necessary to differentiate the optimization and enhancement strategies for each type of ecological space and its ecosystem services according to local conditions, and the conservation of important ecological spaces in the metropolitan area should be continuously strengthened, followed by joint protection and control of ecological red lines in neighboring areas, so as to promote territorial spatial carbon reduction and sink enhancement activities, thus contributing to the steady improvement of the net carbon sink efficiency of the Shanghai Metropolitan Area in general. The research clearly demonstrates the positive effects of enhancing water-related ecosystem services and conserving important ecological spaces on regional carbon sinks and reduction, and effectively reveals an effective path for synergistic carbon reduction in the region, which may provide certain reference for improving territorial spatial management. </sec>

Exploring the spatio-temporal variation characteristics of carbon source and carbon sink under different disposal methods of crop straw is of great significance for optimizing the utilization policy of crop straw resources in China and realizing the goal of maximizing carbon emission reduction and carbon neutralization. Based on data from National Statistical Yearbook, we examined the changing trends of both the amount and value of carbon emission, carbon emission reduction, carbon sink enhancement under different crop straw disposal methods in 31 provinces of Chinese mainland. The results showed that the mean annual carbon emissions of straw burning in China from 2008 to 2019 were 8.74 million tons of CO2e. Since 2014, the mean annual reduction rate of carbon emissions was 17.3%. The mean annual carbon emission reduction of energy utilization was 39.82 million tons of CO2e, with solid briquette fuel produced by straw contributing the most with a contribution of about 98%. The amount of carbon sequestration of straw returning to field was increasing annually, with an average annual value of 271 million tons of CO2e. There was a carbon ecological surplus in straw disposal in China. The annual growth rate of net carbon emission reduction was 9.8%. The net carbon emission reduction intensity and its value were increasing, reaching 2.62 t·hm-2 and 76.19 yuan·hm-2 in 2019, respectively. A spatial pattern of 'high in the east and low in the west' was observed for the mean annual carbon emissions of straw, energy carbon emission reduction, carbon sink of straw returning to the field, and net carbon emission reduction in China, with main external characteristics of the regional differences and spatial aggregation.

Increasing the carbon sink capacity of terrestrial ecosystems is a primary strategy to mitigate climate change and achieve the "carbon neutrality" goal. Clarifying the status and future dynamics of carbon sink of terrestrial ecosystems in Northeast China is crucial for achieving "carbon neutrality" as this region is a core contributor to carbon sink in China's terrestrial ecosystems. Here, we systematically summarized current research on carbon sink of terrestrial ecosystems across Northeast China, including the measurements and spatial-temporal patterns of carbon sinks, driving mechanisms of carbon sinks, the assessments of carbon sink potential, and technologies for increasing carbon sequestration. There are substantial uncertainties in quantifying terrestrial ecosystem carbon sink in Northeast China due to differences in data sources and methods, especially for forest carbon sink measurements, ranging from 0.020 to 0.157 Pg C·a-1. Carbon sink function depends on carbon exchange processes across plant-soil-atmosphere interfaces. The key pathways to enhance carbon sequestration in Northeast China under different temporal and spatial scales remains unclear. Improving terrestrial ecosystem quality is the key and core of carbon sequestration and sink enhancement. However, there is an urgent need to develop a multi-ecosystem collaborative carbon sequestration and sink enhancement technology system for the "dual carbon" goal. Future research needs to develop an accurate carbon sink measurement system that integrates multi-source data and multi-scale technologies to accurately assess the function and potential of carbon sink in Northeast China, focus on the multi-scale driving mechanism of carbon sink functions, develop new technical systems for coordinated enhancement of carbon sink for the Northeast terrestrial ecosystems, and carry out demonstrations of carbon sink enhancement technologies. These efforts will provide the scientific and technological supports for achieving the "carbon neutrality" goal.

Carbon source and sink monitoring is an important prerequisite for realizing the dual-carbon target and the evolution of its spatial-temporal pattern and the spatial-temporal heterogeneity of the driving factors are the scientific basis for the implementation of the emission reduction and sink enhancement policy according to the local conditions, which is of great importance for the sustainable development of the region. Based on the carbon balance of payment relationship, the carbon surplus and deficit of Shaanxi Province counties were calculated in 2000, 2010, and 2020 from land use, and a series of exploratory spatial and temporal analysis methods （ESTDA）, including spatial autocorrelation, cold and hot spot analysis, standard deviation ellipse, and LISA-time pathway, were used to study the dynamics of carbon surplus and deficit in Shaanxi Province at different spatial-temporal scales. From the 21 indicators, six types of major driving factors were selected by principal component analysis, and the geographical spatio-temporal weighted regression model （GTWR） was used to identify their spatio-temporal heterogeneity to construct a comprehensive system of indicators to analyze the carbon deficit and its spatio-temporal heterogeneity in Shaanxi Province. The results showed that： ① A carbon surplus of 8.56 million tons in 2000, a carbon deficit of 3 296 tons in 2010, and a deficit of 33.34 million tons occurred in 2020 in Shaanxi Province, and the growth rate of carbon emissions was much larger than that of carbon sinks, which indicates that it was gradually moving towards carbon peaks in Shaanxi Province； however, there is a long way to go to achieve the goal of carbon neutrality. ② The geographical distribution of the "north deficit and south surplus" phenomenon was visually represented. A carbon deficit was concentrated in the wind and sand area along the Great Wall and Guanzhong plain. The spatial-temporal leap characteristics were more stable. In conclusion, efforts aimed at emission reduction and carbon sink enhancement were strategically directed towards the northern Shaanxi Region. ③ Among various indicator systems including urban construction, natural resources, anthropogenic activities, energy consumption, industrial development, and ecological protection indicator systems, only ecological protection positively drove carbon profit and deficit. Notably, natural resources had the strongest spatial and temporal heterogeneity in their impact on carbon deficit, and energy consumption was positively driven in some areas of Shaanxi Province. The results will provide accurate policy directions for the development of carbon neutral strategies in Shaanxi Province.

As the cornerstone of economic and social development， county-level regions hold significant strategic importance for accurately assessing China's carbon source distribution and carbon sink capacity， as well as effectively guiding the precise implementation of carbon neutrality strategies. The Three Gorges Reservoir Region， as a critical ecological barrier and water regulation zone， represents a significant case study for exploring land use and dual-carbon management. Supported by spatial technologies， this study used Landsat TM/Landsat 8 OLI remote sensing images from the years 2000， 2005， 2010， 2015， and 2020 as data sources. It employed models and methods such as standard deviation ellipses， centroid analysis， spatial autocorrelation analysis， and integrated carbon management to measure and analyze the spatiotemporal evolution of land use， carbon budgets， and carbon balance management zoning in the study area. The results indicate： ① The study area was dominated by forest land and arable land. Construction land increased the most， reaching 1 769.13 km2， while grassland and arable land decreased by 1 677.67 km2 and 810.15 km2， respectively. Other land categories remained relatively stable， exhibiting spatial heterogeneity and unevenness in land use changes. ② Carbon emissions in the Three Gorges Reservoir Region first increased sharply and then gradually decreased， peaking at 39.15 million tons in 2010 and subsequently declining annually to 35.56 million tons， a reduction of 9.19%. The turning point occurred in 2010， with significant differences in the rate of change before and after and a slower declining trend over the subsequent decade. ③ Carbon absorption in the Three Gorges Reservoir Region initially declined sharply （-9.50%）， then increased moderately （6.94% from 2005 to 2015）， followed by a slight decrease （-3.38% from 2015 to 2020）， with significant overall fluctuations. ④ The spatial pattern of carbon budgets was evident， with 55.00% of carbon emissions concentrated in 11 counties at the reservoir tail and efficient， annually increasing carbon absorption in 11 counties at the reservoir belly. The distribution of carbon absorption and emissions was uneven， with higher emissions at the reservoir tail and higher absorption at the reservoir head， warranting particular attention. ⑤ Carbon management zoning indicated that the reservoir tail mainly consisted of compensation payment zones， while the reservoir head and belly were balance zones， exhibiting clustering and heterogeneity in their distribution. There remains significant room for optimization in emission reduction and carbon sink enhancement. The study provides scientific basis and practical guidance for carbon management in the Three Gorges Reservoir Region and similar regions， while also contributing important insights to the ecosystem carbon cycle theory， addressing global climate change， and promoting green and low-carbon development.

In the context of global warming, the Wuhan Urban Agglomeration is actively responding to China’s carbon peak and carbon neutrality goals and striving to achieve a reduction in carbon sources and an increase in carbon sinks. Therefore, it is critical to investigate carbon emissions from land use. This study uses the carbon emission coefficient method to calculate carbon emissions from land use in the Wuhan Urban Agglomeration, analyzes its temporal and spatial changes and differences in urban structure, and couples with the Markov–PLUS model to simulate and predict the carbon emissions of four scenarios of land use in 2035. The research found the following: (1) during the Wuhan “1+8” City Circle stage, carbon sources and emissions increased steadily, with average annual growth rates of 1.92% and 1.99%, respectively. Carbon sinks remained stable and then decreased, with an average annual growth rate of −0.46%. (2) During the Wuhan Metropolitan Area stage—except for 2020 and 2021, which were affected by COVID-19—carbon sources, sinks, and emissions continued to grow in general, and the average annual growth rates increased to 4.46%, 1.58%, and 4.51%, respectively. (3) In terms of urban structure differences, Wuhan is a high-carbon optimization zone; Xianning, Huangshi, and Huanggang are ecological protection zones; other cities, such as Ezhou, Xiaogan, and Xiantao are comprehensive optimization zones; and there is no low-carbon development zone. (4) The multi-scenario simulation results show that carbon sources and emissions are the highest under the economic development scenario, with values of 100.2952 and 9858.83 million tons, respectively, followed by cropland protection, natural development, and low-carbon development scenarios. Under low-carbon development, carbon sinks were the highest, with values of 1.9709 million tons, followed by natural development, economic development, and cropland protection scenarios. The research results are conducive to the formulation of carbon peak and neutrality goals as well as low-carbon development plans for the Wuhan Urban Agglomeration.

Excessive carbon emissions lead to global warming, which has attracted widespread attention in the global society. Carbon emissions and land use are closely related. An analysis of land use carbon emissions and carbon fairness can provide guidance for the formulation of energy conservation and emission reduction policies. This study uses data on agricultural production activities, land use and energy consumption and uses the carbon emission coefficient method to calculate carbon emissions and carbon absorption. The tendency value is used to analyze trends in land use carbon emissions and carbon absorption. The Gini coefficient, ecological support coefficient and economic contributive coefficient are used to analyze the fairness and difference of carbon emissions. The results showed that: (1) During the study period, there were fewer provinces with rapid growth in carbon emissions and carbon absorption and more provinces with slow growth. (2) Cultivated land and woodland are the main carriers of land use carbon absorption, and most provinces steadily maintain the type of carbon absorption to which they belong. (3) Carbon emissions from construction land are the main source of total carbon emissions, and the high concentration areas of carbon emissions are mainly located in the more economically developed areas. (4) There are obvious regional differences in the net carbon emissions. By 2015, Shanxi–Shandong High–High agglomeration areas and Yunnan–Guangxi Low–Low agglomeration areas were finally formed. (5) The distribution of carbon emissions in different provinces is not fair, and the spatial distribution is obviously different. Based on the analysis results, relevant suggestions are made from the perspectives of carbon emission reduction and carbon sink enhancement.

By the end of 2020, most countries in the world have successively proposed carbon-neutral targets. Among them, the major economies in the world, such as the United States (USA), the European Union, Japan, and Canada, have proposed to achieve carbon-neutral targets by 2050. As the world’s largest carbon emitter, China has a total carbon emissions of more than 11.3 billion tons, accounting for about 30% of global carbon emissions. Therefore, the carbon emission reduction required for China is much higher than that of other economies, and its carbon-neutral tasks are obviously more complex and diversified. On 22 September 2020, the Chinese government announced in the 75th Session of the UN (United Nations) General Assembly (New York, USA) that China aims to achieve carbon neutrality before 2060. The announcement of the carbon-neutral target clearly indicated that China needs to carry out a self-revolution to achieve zero CO2 emissions before 2060. The concept of carbon neutrality is essentially a balance between carbon sources and carbon sinks. The carbon source is the process of releasing CO2 into the atmosphere, and the carbon sink is the process of absorbing CO2 from the atmosphere. Investigating the atmospheric system within a certain period, when the amount of CO2 emitted by all carbon sources into the system is equal to the amount of CO2 absorbed by all carbon sinks from the system, carbon neutrality can be achieved. There are various carbon sources and sinks in nature with complicated relationships. Among them, the most important carbon source related to human activities is energy production. In 2020, China’s power sector emitted about 4 billion tons of CO2 per year, which is close to 40% of the total emissions. Thus, the power sector is one of the key areas in emission reduction to achieve the carbon-neutral goal. Building a carbon-neutral power system is the only way to achieve decarbonization in the energy sector. Based on the carbon balance principle, this paper proposed the critical equation of carbon neutrality for power systems. And the further strategies in establishing a carbon-neutral power system were explored according to the carbon neutrality equation: (1) Improve energy efficiency thus reducing the consumption of carbonaceous energy; (2) adjust the energy structure and reduce the proportion of carbonaceous energy; (3) rebuild the balance of sources and sinks by adopting CO2 capture, utilization and storage (CCUS) technology to achieve low-carbon utilization of carbonaceous energy. Results indicate that, although improving energy efficiency of carbonaceous energy is effective in CO2 mitigation, it is limited by the declining energy saving potential of thermal power plants to be the main technical way in carbon emission reduction. Besides, increasing the proportion of renewable energy can quickly reduce the carbon emission intensity of the power system, which is currently the main technical way to reduce the CO2 emission of the power system. However, although energy conservation and the development of renewable energy can reduce the carbon emission intensity of the power system, the CCUS technology and the negative emission technology will be indispensable to achieve the goal of carbon neutrality. And the large-scale promotion of the CCUS technology must overcome technical obstacles of the rather high energy consumption of CO2 capture. Thus, building a carbon-neutral power system in the future requires a combination of energy efficiency, renewable energy and CCUS technology.

Carbon sink enhancement is of great significance to achieving carbon peak and carbon neutrality. This study firstly estimated the carbon sink in the Beijing–Tianjin–Hebei Region using the carbon absorption coefficient method. Then, this study explored the differentiation of carbon sink enhancement potential with a carbon sink–economic carrying capacity index matrix based on carbon sink carrying capacity and economic carrying capacity under the baseline scenario and target scenario of land use. The results suggested there was a remarkable differentiation in total carbon sink in the study area, reaching 2,056,400 and 1,528,300 tons in Chengde and Zhangjiakou and being below 500,000 tons in Langfang and Hengshui, while carbon sink per unit land area reached 0.66 ton/ha in Qinhuangdao and only 0.28 t/ha in Tianjin under the baseline scenario. Increasing area and optimizing spatial distribution of arable land, garden land, and forest, which made the greatest contribution to total carbon sinks, is an important way of enhancing regional carbon sinks. A hypothetical benchmark city can be constructed according to Qinhuangdao and Beijing, in comparison with which there is potential for carbon sink enhancement by improving carbon sink capacity in Beijing, promoting economic carrying capacity in Qinhuangdao, and improving both in the other cities in the study area.

• Identified 3 types of potential spaces for carbon sink enhancement in Beijing. • Beijing's ecological carbon sink may rise to 10.84–11.48 million tons by 2035. • Additional afforestation offers minimal carbon sink benefits. • Sustainable forest management and restoration are key to carbon sink enhancement. • Systematic planning and governance strategies for ecological space were proposed. Beijing proposes to take the lead in achieving carbon neutrality by 2050, so the ecological carbon sink needs to be improved urgently, but there are still practical problems such as scattered layout and imperfect functions of ecological carbon sink spatial elements such as water, forest and farmland due to the lack of overall coordination. Based on establishing the relationship between the territorial ecological spaces and the ecosystem carbon pools, this paper systematically evaluated the current status of the ecological carbon sink across the entire area and all elements of the territorial space in capital Beijing, and identified potential spaces for carbon sink enhancement, including afforestation-suitable barren land and planned afforestation site, construction land retreat for ecological space recovery, and degraded forest. By combining the urban master plan and relevant departmental targets, the medium- and long- term carbon sink potential was simulated. The results showed that: (1) The current status of the ecological carbon sink in the whole territory is about 7.58 million tons, which is much smaller than the current carbon emission level, and its spatial difference gradient is obvious, but there is also a relative imbalance within the circle. (2) The reasonable range of the city's ecological carbon sink growth potential by 2035 is about 10.84–11.48 million tons, and the potential for increasing carbon sink mainly comes from sustainable forest management and the restoration of degraded forests, while the carbon sink increase from new afforestation is only <0.3 million tons. Accordingly, ecological restoration strategies for territorial space were put forward in terms of degraded forests, untreated mines, demolished illegal land use, wetlands, urban green spaces and farmlands, and the policy implications of territorial ecological space planning and governance in the capital Beijing was proposed to replace increment with spatial optimization and multi-objective coordination.

As a major global carbon emitter， China's provinces and municipalities contribute more than 90% of the country's carbon emissions， while the rest is mainly emitted by special administrative regions， trans-regional emission sources， and airspace and sea areas. How to accurately predict the carbon emissions of different provinces and municipalities and formulate emission reduction policies is the basis for realizing the national dual-carbon target and high-quality synergistic economic development. Taking Shaanxi Province， located in Northwest China， as an example， a top-down and bottom-up integrated RR-STIRPAT-LEAP model is developed using relevant cross-section data from 2000 to 2021， and the prediction accuracy is improved by optimizing the weights of sub-models. On this basis， the carbon emissions of Shaanxi Province from 2022 to 2060 are forecasted， and five joint scenarios are designed to simulate the dual-carbon pathway of Shaanxi Province in combination with the carbon sink absorption model. The ReliefF algorithm is used to analyze the important potential drivers of carbon emission reduction. The results found that the prediction accuracy of the RR-STIRPAT-LEAP-Shaanxi model was significantly better than that of a single model， and the optimized model error was 0.24%. It was predicted that Shaanxi Province will reach its peak in 2030， and the emissions （in terms of tons） will be 419.09 million tons （Mt）. Under the joint scenario， macro-control-EMT-F Shaanxi Province will achieve carbon neutrality by 2060， with an emission of -25.69 million tons， indicating that ecological carbon sinks played an important role in achieving carbon neutrality. Comparison of carbon emission changes under different joint scenarios revealed that upgrading the energy structure and improving energy efficiency were the key drivers of Shaanxi Province's low-carbon transition and that the implementation of macroeconomic and sectoral energy consumption control strategies could reduce more carbon emissions. ReliefF showed that Shaanxi Province's carbon emission reduction focused on the following industrial sectors in order： industry &gt; power generation &gt; agriculture &gt; residential sector &gt; transportation， storage， and postal services &gt; construction &gt; other services. Among them， agriculture was not only an important source of carbon emissions but also an important carbon sink， and its potential for emission reduction should not be ignored. After comprehensively analyzing the short and medium to long-term carbon emission pathways and carbon emission reduction drivers， this study provides a pathway map for the synergistic development of Shaanxi Province， which will provide a scientific basis for government policymakers and relevant enterprises to formulate low-carbon and high-quality economic development plans.

The Hu-Bao-O-Yu urban agglomeration is an important energy exporting and high-end chemical base in China, and is an important source of carbon emissions in China. The early achievement of peak carbon emissions in this region is particularly crucial to achieving the national carbon emission reduction targets. However, there is a lack of multi-factor system dynamics analysis of resource-dependent urban agglomerations in Northwest China, as most studies have focused on single or static aspects of developed urban agglomerations. This paper analyses the relationship between carbon emissions and their influencing factors, constructs a carbon emission system dynamics model for the Hu-Bao-O-Yu urban agglomeration, and sets up different single regulation and comprehensive regulation scenarios to simulate and predict the carbon peak time, peak value, and emission reduction potential of each city and urban agglomeration under different scenarios. The results show that: (1) Hohhot and Baotou are expected to reach peak carbon by 2033 and 2031 respectively, under the baseline scenario, while other regions and the urban agglomeration will not be able to reach peak carbon by 2035. (2) Under single regulation scenarios, the effect of factors other than the energy consumption varies across cities, but the energy consumption and environmental protection input are the main factors affecting carbon emissions in the urban agglomeration. (3) A combination of the economic growth, industrial structure, energy policy, environmental protection, and technology investment is the best measure to achieve carbon peaking and enhance the carbon emission reduction in each region as soon as possible. In the future, we need to coordinate the economic development, energy structure optimisation and transformation, low-carbon transformation of industry, strengthen research on carbon sequestration technology, and further increase the investment in environmental protection to make the Hu-Bao-O-Yu urban agglomeration a resource-saving urban agglomeration with an optimal emission reduction.

The influence of rapid urbanization and land use changes on terrestrial carbon sources/sinks in Guangzhou, China

In recent years, China has been vigorously carrying out the planning and implementation of Sponge City. Since the implementation of Sponge City projects involves substantial materials and energy consumption, it is significant to account corresponding carbon emissions and sinks. The existed studies about carbon emission of stormwater management measures, however, are not able to take the whole life cycle and different facilities into consideration. Therefore, this study develops a comprehensive accounting model based on Intergovernmental Panel on Climate Change (IPCC) guidelines and life cycle assessment (LCA) method to predict carbon emissions and carbon sinks of Sponge City projects more comprehensively and accurately. The model is applied to an actual residential community in Shanghai as a case study. Results show that the total indirect carbon emission is estimated to be 774,277 kg CO2 eq during a 30-year lifespan, among which carbon emissions from operation and maintenance phases are 2570 kg CO2 eq/year and 7309 kg CO2 eq/year, respectively, both directly proportional to the service life of the facilities. Three kinds of achievable carbon sinks are carbon sequestration in green space (5450 kg CO2 eq/year), carbon sink from rainwater utilization (15,379 kg CO2 eq/year) and carbon sink from runoff pollutant removal (19,552 kg CO2 eq/year). Carbon neutrality is expected to be reached after approximately 19 years. The established carbon emission accounting model can contribute to better planning and construction of Sponge City in China and enhance further energy conservation and carbon emission reduction.

Climate change leads to permafrost thawing, accelerating carbon emissions increases, challenges the goal of climate change mitigation. However, it remains unknown whether implementing ecological restoration projects in Alpine areas can offset the adverse effects of permafrost thawing locally. Here we took the Qinghai‒Tibet Plateau as an example to explore this issue based on the improved Biome-BGCMuSo model. We found future climate change-induced permafrost thawing will decrease carbon sink. Projects’ carbon sink enhancement could fully counteract the permafrost thawing-induced carbon loss. Additionally, future warmer and wetter climates will enlarge the suitable area for restoration. If these areas are taken into account, carbon sink attributable to Projects will further increase. These results indicate that ERPs have the potential to combat future permafrost thawing-induced carbon loss, and their contribution will be further amplified by future climate change.