Search

Soil organic carbon (SOC) plays a central role in ecosystem carbon sequestration and climate change mitigation, and its stability and dynamics are related to sourcing from microbial vs. plant residues. However, SOC sourcing and its regulating mechanisms remain poorly understood in soil's most bioactive compartment, the rhizosphere, which may differ from non-rhizosphere and under different mycorrhizal tree species. To fill the knowledge gap, here we collect the rhizosphere and non-rhizosphere soils under an arbuscular mycorrhizal (AM; Castanopsis eyrie) vs. an ectomycorrhizal (ECM) tree species (Pinus massoniana) of varied tree diameters (i.e., ages) in the Gutianshan subtropical forest of China. Plant and microbial residual components are quantified by lignin phenols and amino sugars, respectively. Coupled with the measurements of soil, microbial community and plant litter properties, we assess potential mechanisms (i.e., saprotrophic bacteria competition, microbial necromass recycling/reuse, and substrate quality control) influencing the distribution of plant and microbial residues in the rhizosphere vs. non-rhizosphere. We show that lignin phenols are more concentrated in rhizosphere than non-rhizosphere SOC, especially under the ECM trees showing inhibited saprotrophic decomposition induced by competition between ECM fungi and (saprophytic) bacteria. Amino sugars are also more concentrated in the rhizosphere of ECM trees due to ECM fungal contribution, but not under AM trees exhibiting reduced fungal necromass stability partially reflected by low biomass-normalized necromass accumulation coefficients in the rhizosphere. As a result, ratios of amino sugars to lignin phenols are relatively lower in the rhizosphere than non-rhizosphere under AM tree, challenging the presumed microbial dominance in rhizosphere carbon accumulation. These results highlight differences in and controls on rhizosphere SOC sourcing related to different mycorrhizal tree species, providing new information on the mechanisms regulating soil carbon dynamics in root-soil systems. • Rhizosphere has more lignin in SOC than non-rhizosphere, especially under ECM tree. • Saprotroph inhibition contributes to lignin preservation in ECM tree rhizosphere. • AM tree rhizosphere has a low fungal necromass accumulation coefficient. • Amino sugar-to-lignin ratio is lower in AM tree rhizosphere than non-rhizosphere. • Our result challenges the presumed microbial dominance in rhizosphere SOC. [ABSTRACT FROM AUTHOR]

This study developed a climatic-economic-technological integrated assessment model named CIECIA-TD-F. Based on model, the implementation effects of low carbon technology financing on climate mitigation, technology promotion, and economic development in the context of climate change cooperation were studied. The results indicate that carbon reduction, under the current pledged climate financing scale, is limited. Global surface warming in 2100 is still around 2.38 °C even when the technologies are globally shared. Low carbon technology financing improves technology R&D and absorptive capacities of the least developed countries. Their carbon reduction rates reach 50 percent under the capacity principle. However, donations impair the R&D inputs of developed countries and delay their advanced technological progress, leading to 1 percent more carbon emissions. This limits the imitations of China and Russia in turn by decreasing their imitation numbers by 1–2 percent. Collecting 800 billion USD per year from 2030 to 2100 is a climatically effective means. It holds global warming to 1.99 °C. However, the donors suffer more than 1 percent of economic losses. That indicates the economic feasibility of this means is weak. On this basis, we proposed a Pareto-improvement scheme which combines financing with technology sharing and national R&D improvements. This policy mix both achieves the 2 °C goal and protect the economic benefits of all countries. Thus, policy mix combining different measures will be more suitable for improving reduction effects and achieving multiple goals. Compared with sole technology financing, it has more significant global carbon governance meanings and is noteworthy in future climate negotiations. • Nine combinations of typical collection and dispensation principles were assessed. • The current scale of climate financing pledge was insufficient. • 2 °C goal can be achieved by improving financing scale dramatically in short term. • Advanced technology innovation was delayed for the economic losses of the funding donors. • A Pareto improving scheme was proposed. [ABSTRACT FROM AUTHOR]

Carbon capture, utilization, and storage (CCUS) is a crucial technology for global climate mitigation. To implement large-scale CCUS, decisions about where and how to build a CO 2 transportation network are urgently required. However, previous studies are limited in proposing the economical transportation network for CCUS that considered comprehensive risks from socio-economic, geographical and geological factors. Here, we develop a pipeline layout planning model to investigate the cost-effective and reliable transportation network for CCUS. Results show that to meet the annual CO 2 emission reduction target of 654 million tons for CCUS in the coal-fired power sector under China's carbon neutral goal, pipelines with a total length of 17,589 km need to be constructed. The emission sources can be transported in pipelines with an average radius of 58 km, and with diameters of 8, 12, and 16 inches. Northeast, north, and northwest China are the main areas suitable for pipeline construction. • Northeast, North, and Northwest in China are vital areas for capture, transport, and storage. • Five large-scale pipeline network groups can be constructed in China. • Pipeline construction is greatly affected by a variety of practical factors. [ABSTRACT FROM AUTHOR]

Carbon capture, utilization, and storage (CCUS) is a crucial technology for global climate mitigation. To implement large-scale CCUS, decisions about where and how to build a CO 2 transportation network are urgently required. However, previous studies are limited in proposing the economical transportation network for CCUS that considered comprehensive risks from socio-economic, geographical and geological factors. Here, we develop a pipeline layout planning model to investigate the cost-effective and reliable transportation network for CCUS. Results show that to meet the annual CO 2 emission reduction target of 654 million tons for CCUS in the coal-fired power sector under China's carbon neutral goal, pipelines with a total length of 17,589 km need to be constructed. The emission sources can be transported in pipelines with an average radius of 58 km, and with diameters of 8, 12, and 16 inches. Northeast, north, and northwest China are the main areas suitable for pipeline construction. • Northeast, North, and Northwest in China are vital areas for capture, transport, and storage. • Five large-scale pipeline network groups can be constructed in China. • Pipeline construction is greatly affected by a variety of practical factors. [ABSTRACT FROM AUTHOR]

Community shared solar (CSS) program has great potentials in contributing to the complete decarbonization of the power sectors worldwide. Few research have focused on its potential diffusion from the user perspective. This paper fills the gap by conducting a survey-based unlabeled choice experiment in the Guangdong Province, China to investigate the determinants of potential users' willingness to participate in CSS programs. We analyzed the survey data using a random parameter logit model. Our results show that users are more likely to participate in CSS programs with lower upfront payment, trialability, shorter payback period, a public utility as provider and larger impact on climate change mitigation. However, they are likely to accept longer payback period in CSS programs with higher participation rate because of the potential benefit from interpersonal communication. Users' previous knowledge of CSS programs and income will also increase their willingness to participate in CSS programs with higher upfront payment. Our results provide important implications for designing policies and business models to promote the distributive renewable energy in China. • Community shared solar is widely accepted among surveyed individuals in our choice experiment. • The business model, and the ownership structure of community shared solar affect its potential adoption. • The interpersonal communication and public promotion of community shared solar program can increase its popularity. [ABSTRACT FROM AUTHOR]

[Display omitted] • The greening rate increased with time after cascade-dam implementation. • Temperature was the most significant driving force on vegetation growth. • Temperature and sunshine hours positively affected vegetation. • Vegetation was negatively correlated with precipitation and vapor pressure deficit. The eco-environment in ecologically fragile regions has received increasing concern due to its vulnerability to climate changes. Determination of vegetation dynamics is a prerequisite for sustainable management of eco-environment evolution due to its vital role in regulating earth system and ecosystem services. China′s Three Gorges Reservoir area (TGRA), as a typical ecologically fragile region, was selected to explore its vegetation dynamics and response to local climate in different periods (1982–2020) of GZD-TGD (Gezhou Dam-Three Gorges Dam). The 1982–2020 NDVI dataset was obtained by integrating the overlapping period (2001–2015) of GIMMS NDVI and MODIS NDVI. The results demonstrated that TGRA exhibited a generally greening trend in 1982–2020, and the greening rate increased with the implementation of GZD-TGD, particularly in the last 20 years, which greatly promotes the capacity of vegetation carbon sink. At the annual scale, the mitigation of climate warming occurred with GZD-TGD implementation, particularly after the first impoundment of TGD (−0.0114 ℃yr−1). At the seasonal scale, a certain cooling effect in summer and a warming effect in other seasons (especially in winter) induced by this cascade project were observed, which became more pronounced after the water level reached 175 m. Furthermore, temperature had the most significant positive effect on vegetation dynamics, which increased with GZD-TGD implementation. The driving force of precipitation, VPD (vapor pressure deficit) and sunshine hours was relatively less significant but could not be ignored, with negative contributions from precipitation and VPD and positive contribution from sunshine hours. These findings provide further insights into the effect of climate changes mediated by GZD-TGD on vegetation growth and facilitate the dissection of the complex soil–plant-atmosphere feedback interaction. [ABSTRACT FROM AUTHOR]

Agricultural land carbon opportunity cost (COC) characterizes potentials for carbon sequestration through ecosystem restoration, which is a critical component for formulating nature-based solutions to mitigate climate change. Yet existing relevant estimates still stayed at global scale, lacking estimates at national and provincial scale. Here, we integrated multi-source downscaled data to estimate the magnitude of land COC for 20 categories of crops and livestock in 30 provinces of China. Results show that beef got the highest land COC with about 29% of the national total, and COC per unit production of beef was much higher than that of other products. The high beef-induced COC was primarily caused by vast amount of grass feed consumed by beef cattle, resulting in native forest land being cleared into grazing land. Moreover, both land COC and crops yield per unit area of cropland enhanced with latitude decrease, but the increase rate of the former was much higher than that of the latter. Therefore, improving utilization efficiency of existing grazing land and raising yields per unit area of existing croplands in low-latitude provinces, rather than clearing new native forest land into grazing land and cropland, would have great functions on declining national total land COC for agricultural products. The research could also contribute to discussions of local tradeoffs between land carbon storage and agricultural production and then inform climate mitigation strategies. • Land carbon opportunity cost (COC) by province-product in China was estimated. • Sichuan, Hunan, and Guangxi had the largest capacity to restore carbon. • Beef production contributed the most (29%) of national total COC. • Land COC per unit yield enhanced substantially with decreasing latitude. • Tradeoffs between carbon stock and agricultural production needs to be discussed. [ABSTRACT FROM AUTHOR]

• Three behaviors are responsible for 63–81% of indirect household carbon emissions. • Household carbon inequality larger than income inequality in poorer provinces. • On average, over 50% of a province's carbon accounts are self-production emissions. • Most CO 2 inflows/outflows of a province relate to 5 consuming/producing provinces. • Most CO 2 inflows/outflows of a province relate to 3 local/non-local sectors. The design of "fairness" and "justice" climate policies for controlling indirect household carbon emissions (IHCEs) requires joint efforts from the demand side and supply side. On the demand side, this study constructs behavior-specific IHCEs inventory for different household groups (differed by income level) in different regions to identify high-emitting households and corresponding high-emitting consumption behaviors. On the supply side, the "Carbon Account" is set up for different regions regarding various household consumption behaviors to screen all potential emitting-related stakeholders in the entire demand–supply chains. Using 25 Chinese provinces as study cases, the findings indicate that carbon inequalities across household groups are greater than income inequalities in poorer provinces, whereas the opposite is true in richer provinces. For most high emitting households (most were middle-high- and high-income households) in 25 provinces, Food & Beverage, Housing, and Durable goods are the top 3 carbon-intensive consumption behaviors, together accounting for 64–81% (72% on average) of total IHCEs. For the three carbon-intensive behaviors, the province-level carbon account analysis shows that a province's self-production emissions (local consumption, local emissions) took up an average of 52%, 70%, and 47% of its carbon accounts. An average of 83%, 80%, and 79% of net carbon transfer-in of a province (non-local consumption, local emissions) sourced from its 5 major consuming provinces, while 76%, 81%, and 77% of transfer-out (local consumption, non-local emissions) of a province were outsourced to its 5 major producing provinces, respectively. Furthermore, according to the sector-level carbon accounts, an average of 75%, 89%, and 76% of the sector carbon transfer-in, and an average of 72%, 80%, and 79% of the sector carbon transfer-out of a province were emitted by three dominant local or non-local industrial sectors, respectively. This study could provide policy implications for local governments to take joint climate mitigation strategies between the demand-side and supply-side targeting high-emitting household consumption behaviors. [ABSTRACT FROM AUTHOR]

• CO 2 sequestration and EGR are experimentally evaluated in two shale gas reservoirs. • Pore heterogeneity and connectivity are evaluated via multifractal analysis. • Shale composition controls on gas storage is evaluated from gas adsorption measurements. • Links between MICP and gas adsorption measurements were used to evaluate EGR suitability. In the global effort toward climate change mitigation, geologic storage of CO 2 in shale plays is becoming critical while it can improve production from these reservoirs. In this study, the gas storage capacity and CO 2 sequestration suitability of the Longmaxi and Niutitang shale gas reservoirs is investigated and compared via XRD analysis, programmed pyrolysis, low pressure N 2 and CO 2 adsorption, high pressure CH 4 adsorption, and MICP analysis. Results showed that clay and TOC controls on micropore heterogeneity and connectivity happens only within the Longmaxi Formation. Furthermore, both components play a role in the adsorbed quantities of gas in the formation which revealing a higher storage capacity in mesopore-macropores. This was verified by a positive correlation between adsorbed volume within the mesopore-macropore space. The Longmaxi Formation was also found to own better pore connectivity and PSD homogeneity of mesopore-macropores, indicating easier pathways for CO 2 movement channels within the pore network. Furthermore, the samples from the Longmaxi exhibited a positive relationship between adsorbed volume with the CO 2 breakthrough pressure and median pore diameter, alike between the mesopore-macropore volume and CO 2 breakthrough pressure. This means, the injected CO 2 will displace adsorbed methane within the mesopore-macropore and will be adsorbed and stored in such pores. Overall, superiority of the Longmaxi shale over the Niutitang for CO 2 storage and EGR would be significant for future operations in similar shale gas reservoirs in China and around the globe. [ABSTRACT FROM AUTHOR]

China, the world's largest CO 2 emitter, is making every effort to transition to a low-carbon economy and fulfill its part of a concerted global commitment to combating climate change. In tandem with decarbonizing energy and industries, feasible supplementary measures are urgently needed to help remove anthropogenic CO 2 from the atmosphere. A burgeoning literature has emphasized the CO 2 removal capability of land re-naturalization (such as afforestation and wetland restoration), thereby regarding cognate land-use conversions as Nature-based Solutions (NbS) and potential climate policy options. However, little empirical evidence exists concerning the effectiveness of different land re-naturalization pathways (such as converting wetlands to forests or agricultural lands to grasslands), and it also remains unclear how NbS alternatives (i.e., land-use conversions resulting in negative CO 2 emission) and non-NbS options (i.e., land-use conversions resulting in positive CO 2 emission) could affect the social cost of carbon (SCC), a conventional measurement for prescribing carbon mitigation approaches. This study aims to fill in this knowledge gap via embedding NbS into the dynamic integrated climate-economics (DICE) model to quantify their impacts on the SCC. Using the Pearl River Delta region (south China) as a case study for the temporal horizon during 2000–2020, we find that both positive and negative CO 2 fluxes have been brought by different natural/semi-natural land conversions, affecting the SCC correspondingly. A total of 7 out of 17 types of land-use conversions could be identified as feasible NbS interventions, including forest restoration, forest-to-wetland, grassland-to-forest, grassland-to-wetland, grassland-to-cropland, cropland-to-forest, and cropland-to-wetland conversions, which could reduce the SCC values (comparing 2020 base-year with 2000 base-year) by 0.0132, 0.0009, 0.0033, 0.0030, 0.0001, 0.0082, and 0.0001 (USD/tCO 2), respectively. While the SCC is mainly determined by energy and industrial structure, the overall effect of NbS is larger than the sum of land urbanization and non-NbS land-use conversions. Via embedding the real-world inter-dynamics of land-use conversions into the SCC quantification, this study presents a pioneer assessment of the impacts of NbS on the SCC in an integrated framework, sheds important insights into the effectiveness of NbS, and offers practical implications for policy-makers to devise comprehensive policies covering all feasible CO 2 abatement options. [ABSTRACT FROM AUTHOR]

[Display omitted] • TUEEC in 10 urban agglomerations in China are substantially different. • TUEEC within urban agglomeration have an impact on CO 2 emissions. • Ecological construction partially mitigated emissions growth. • Guarding against unsustainable development is vital to carbon neutral. Urban agglomerations are major generators of CO 2 emissions owing to human socioeconomic activities. Evaluating the trade-offs between urban expansion and ecological construction during rapid urbanization is a crucial step towards climate change mitigation and carbon neutrality. This study investigated the impacts of trade-offs between urban expansion and ecological construction on CO 2 emissions using multi-source data and spatial and statistical analysis. Ten urban agglomerations in China, with various development levels, were selected as study areas. The results indicated that (1) urban development in the 10 urban agglomerations expanded by 90%–288.9%, while ecological land changed by −28.1–2.3%. (2) CO 2 emissions grew by 154.2–291.2% in urban agglomerations, and the south and east of China emitted more CO 2. The high-value clusters of CO 2 inside of all urban agglomerations expanded outward from cities. (3) Urban expansion increased emissions, while ecological construction partially mitigated emissions growth. Moreover, ecological development within cities helps to reduce excessive urban emissions and should be given more attention. (4) It is as important to guard against unsustainable development as it is to reduce existing high emissions. Low-carbon development paths must continue to be supported in western China. On the basis of the results, we identify important implications for meeting China's target of carbon neutrality. These contribute to an understanding of future development modes for urban agglomerations and reveal the impact of trade-offs of land use on CO 2 emissions. [ABSTRACT FROM AUTHOR]

With the aim to meet customers diverse energy needs by an economical and ecological means, integrated energy system has become a popular choice. Amongst various integrated energy system coupling configurations, individual heating infrastructure entails painstaking attention due to rapid expansion. Individual heating network plays a massive role in carbonizing the atmosphere as traditionally individual heating demands are fulfilled by fossil fuel-fired (natural gas and coal) boilers. Recently, trend is heading towards the integration of energy efficient technologies like micro combined heat and power and heat pumps to replace fossil fuel boilers. However, individual heating performance evaluation is generally investigated by energy analysis that employs only the first law of thermodynamics, thereby exergy analysis assessment and its comparison with energy analysis become noteworthy to measure actual performance. In this work, energy and exergy analysis of the individual heating network of China for the year 2030 is performed under the framework of both laws of thermodynamics. The proposed work includes various technological options like Hydrogen fired micro combined heat and power, natural gas fired micro combined heat and power and heat pumps to replace the fossil fuel boilers intending to attain an economically viable and carbon-free environment. At first, energy and exergy efficiencies of the aforementioned heat producing components are computed and afterwards EnergyPLAN technical simulation strategy is employed to evaluate performance in terms of costs, CO 2 emissions and primary energy supply. Subsequently, a comparison of both analysis is provided in order to present the difference between the two analysis which substantiates that exergy analysis provides inferior results than energy analysis as depicted in case 3 where heat pumps inclusion appears to be the most decarbonized alternative for energy analysis but corroborates vice versa for exergy analysis. However, exergy analysis complements the energy analysis that helps evaluating the actual performance of system in relation to climate change mitigation and cost-effectiveness. • Energy and exergy analysis of individual heating network of China is performed. • Economical and decarbonized environment is proposed. • Exergy analysis results are inferior to energy analysis. • Heat Pump is considered worse alternative according to exergy analysis. [ABSTRACT FROM AUTHOR]

• The SOC content in macroaggregates was 8–67% higher than that in other aggregates. • Hydrolase activities were positively correlated with the SOC content in aggregates. • Microbial community diversity decreased as the soil aggregate size increased. • Forty-year-old orchards primarily promoted SOC storage in macroaggregates. Soil organic carbon (SOC) is closely related to ecosystem functions and services, such as biodiversity conservation and the mitigation of climate change. Soil aggregates are among of the most important microbial hotspots and are an important material for C cycling. However, the effects of microbial properties such as enzyme activities and microbial communities on SOC across different soil aggregates remains unclear. Here, we evaluated the SOC, microbial biomass carbon (MBC) content, hydrolase enzyme activities (i.e., β-glucosidase, α-glucosidase, and sucrase), and microbial communities in different soil aggregates in 7-, 20- and 40-years orchards and newly established orchards in southern China to determine the relationships between the SOC and microbial properties. The aggregate-associated SOC, MBC contents and three enzyme activities were unevenly distributed. The average SOC and MBC contents in > 0.25 mm aggregates increased by 40% and 26%, respectively, compared with those in the other aggregates (< 0.25 mm). The β-glucosidase and α-glucosidase activities in the 0.053–0.25 mm aggregates were the lowest among different aggregates, but the sucrase activities did not differ significantly across soil aggregates of different sizes. The average SOC and MBC contents, and the three enzyme activities in the > 0.25 mm aggregates in the forty-year orchard increased by 2.53-, 1.41- and 2.09-fold, respectively, compared to those in the newly established orchard. Positive correlations with the soil aggregate size were observed for Chloroflexi, and negative correlations were found for Actinobacteriota, Proteobacteria and Acidobacteria. The relative abundance of Ascomycota increased, and the relative abundance of Basidiomycota decreased with increasing orchard age. Our study demonstrated that the increased orchard age (40 years old) accelerated C cycling in soil aggregates of different sizes by increasing aggregate-associated enzyme activities and changing the microbial community composition, and greater SOC accumulation occurred in macroaggregates (> 0.25 mm) than in microaggregates (< 0.25 mm). [ABSTRACT FROM AUTHOR]

The responses of grain yield and greenhouse gas (GHG) emissions to climate warming in rice paddies are serious concerns for both global food security and climate change mitigation. However, the impact of free-air temperature increase (FATI) on grain yield and methane (CH 4) and nitrous oxide (N 2 O) emissions remains unclear for one of the most globally significant rice production practices: the double rice cropping system. Here, we conducted a two-year field experiment to examine the effect of FATI by infrared heaters on grain yield and CH 4 and N 2 O emissions in a double rice field in subtropical China. FATI increased rice canopy temperature by 2.0 °C and soil temperature by 1.2 °C on average but had no effect on either early or late rice yield production. FATI did not affect CH 4 emissions, but significantly increased N 2 O emissions in both the early and late rice seasons. Averaged across two years, N 2 O emissions increased by 0.3 kg ha−1 and 0.7 kg ha−1 in the warmed plots for the early and late rice seasons, respectively. Consequently, FATI enhanced the global warming potential (GWP) and GHG intensity (i.e., yield scaled GWP) in the double rice cropping system. In addition, warming increased the abundance of ammonia-oxidising bacteria, ammonia-oxidising archaea, and a nitrite reductase gene (nirS), but decreased that of a nitrous oxide reductase gene (nosZ). Our results indicate that warming by FATI does not affect grain yield and CH 4 emissions but stimulates N 2 O emissions in the double rice cropping system and therefore promotes a potential positive feedback with future climate warming. • Free-air temperature increase (FATI) with infrared heater was performed in a double rice field. • Moderate warming by FATI had no significant effect on rice yield. • Moderate warming by FATI did not significantly affect CH 4 emissions. • Moderate warming by FATI stimulated N 2 O emissions. [ABSTRACT FROM AUTHOR]

The ever-increasing anthropogenic greenhouse gas (GHG) emissions worldwide make it quite challenging to meet country-specific Nationally Determined Contributions (NDC) targets. Therefore, it is evident that the existing emissions abatement measures need to be taken a step further. Internationally Transferred Mitigation Outcomes (ITMOs) are allowed in Article 6.2 of the Paris Agreement as a cooperative approach to achieving NDC goals. There is a potential to create ITMOs between Canada and China by replacing coal use in China with British Columbia (BC)'s liquefied natural gas (LNG) supply. Replacing coal with LNG in energy generation applications is a promising approach to mitigate emissions. With global and national pressures to reduce emissions, China has created a market for LNG imports to cater to its rising natural gas (NG) consumption due to the coal-to-gas source switching strategy. However, the terms under Article 6.2 requires generated ITMOs to ensure environmental integrity, support sustainable development goals, and have a robust accounting system. Therefore, the current study aims to quantify the life cycle environmental outcomes of generating ITMOs by exporting LNG from BC to Chinese end-users while integrating uncertainties and to provide policy recommendations in adherence with the requirements of Article 6.2. Different LNG export scenarios were generated in the study and environmental impacts of each scenario were assessed and compared using a life cycle assessment (LCA) framework developed by the authors. Sensitivity and uncertainty analyses were conducted to understand the impacts created by the data uncertainties in the final result. By replacing conventional coal with NG, approximately 40–45% and 26%–32% emissions reductions can be obtainable for Chinese textile and chemical industries, respectively. The highest emissions reduction of approximately 60% was observed when coal is replaced with NG for district heating. The life cycle emissions (LCE) quantification framework provided in the study provides stakeholders with a systematic approach to determine the total GHG emissions and emissions reduction potential of different LNG export scenarios. [ABSTRACT FROM AUTHOR]

Achieving the carbon neutral targets before year 2060 is one of the important commitments for mitigating global climate change by Chinese government. However, the manner in which one would maximize the carbon sequestration of the planted forests is still unclear. Estimating accurately the carbon balance in forestry depends highly on the dynamics of numerous delay-released carbon pools (e.g., harvest residues, wood products), thus the strategies used to account for the carbon emissions of these components may have great influences on the decision-making and profitability associated with planted forests. This study developed a tool that allows forest managers and policy makers to analyze the effects of alternative accounting strategies for recognizing carbon emissions on the optimal rotation lengths and profitability of planted forests. The considered carbon balance not only refers to the within-forest pools, e.g., living biomass, harvest residues, annually generated litters and dead trees, but also refers to the outside-forest pools that include wood products, biofuel, operating process and substitution effect. The obtained results indicated that the lengths of optimal forest rotation decreased significantly with increases in site index, planting density and discount rate, while they increased dramatically with increases of carbon price. The gaps in rotation lengths were as large as 13.5 years, 6.9 years, 27.6 years and 11.0 years, respectively for the ranges of site index (10–18 m), planting density (2500–4444 trees per hectare), discount rate (1%–5%), and carbon prices (0–880 CNY/ton CO 2) assumed. The effects of delay-released carbon pools on the optimal rotation lengths were not significant, when the substitution effects of wood products and biofuels were considered under the current carbon trading markets; however, some exceptions were observed when a very high carbon price (880 CNY/ton CO 2) was assumed. [Display omitted] • A management tool that considers carbon balance and wood production was developed. • The optimal rotations are sensitive to forest- and economic-based variables. • The delayed effects of carbon emissions on optimal rotations were offset by substitution effects. • Pricing CO 2 sequestrated in forests can increase optimal rotations and profitability. [ABSTRACT FROM AUTHOR]

[Display omitted] • A bi-level joint-probabilistic programming approach is developed. • It can handle leader–follower issues and joint-probabilistic constraints. • The proposed approach is applied to China's multi-regional energy system model. • The optimal schemes during 2021–2050 under three mitigation scenarios are obtained. • Results are helpful to achieve low-carbon goals in multi-regional energy system. Climate change mitigation and renewable resources utilization are becoming particularly urgent for energy system management. In this study, a bi-level joint-probabilistic programming (BJPP) method is developed for planning multi-regional energy system under different mitigation policies and uncertainties. BJPP can handle leader–follower issues in decision-making process as well as examine the risk of violating joint-probabilistic constraints. Based on the BJPP method, a China's multi-regional energy system (named as BJPP_CMES) model is formulated to provide optimal scheme for energy system planning of China over a long-term horizon (2021–2050) by synergistically minimizing carbon dioxide (CO 2) emission and system cost. A series of scenarios associated with different carbon capture and storage (CCS) levels and violation risks of energy-demand constraints are examined. Results reveal that: (i) the share of non-fossil energy in China's energy supply would keep increasing in 2021–2050, and the highest growth of the renewable supply would occur in Ningxia (rising 47.7%); (ii) Sichuan, Inner Mongolia, and Gansu would be the top three suppliers of renewable electricity; (iii) the CO 2 emission of China would reach a peak of [44.3, 54.8] billion tonnes during the period of 2026–2030; Shandong, Inner Mongolia, and Shanxi would be main contributors of CO 2 emission in the future; (iv) compared with the single-level model, the CO 2 emission from the BJPP_CMES model would reduce by [2.7, 5.7]%; (v) among developed regions, the individual probability level of Jiangsu-Zhejiang-Shanghai is the most significant parameter for both CO 2 emission and system cost. The findings are helpful for decision makers to optimize multi-regional energy system (MES) with a low-carbon and cost-effective manner, as well as to provide useful information for renewable energy utilization and regional sustainable development. [ABSTRACT FROM AUTHOR]

• Energy upgrade is promoted by interprovincial coordinating of economy and resource. • Energy upgrade is determined by change of farmers' preference for low-quality energy. • Energy upgrade can be promoted together in agriculture and rural life. Rural energy upgrade in developing countries is an essential part of the world climate mitigation work. To systematically promote rural energy upgrade, we took the case of China and used a spatiotemporal model to investigate the spatiotemporal characteristics of energy ladders in agriculture and rural life of developing countries. The proportion of clean energy consumption in agriculture showed an interprovincial competition effect, whereas the proportion of oil consumption in rural life showed a demonstration effect. Severe reliance on coal hinders energy upgrade. Urbanisation has improved the clean level of energy use in agriculture but does not significantly affect the in rural life. Technological progress has increased the proportion of clean energy consumption but has little impact on the proportion of oil and gas consumption. The abundance of coal resources has prompted the massive use of coal and coal-fired power. Energy-use habit promotes the use of all types of energy. Except for that of gas, the consumption of different types of energy in agriculture and rural life mutually promotes. In summary, the development of energy technologies should be established based on the regional resource endowment and economic development level. Also, subsidy principles for clean energy projects should be established based on the development level of the agriculture and residents' income. Rural energy upgrade is coordinated with urbanisation and the modernisation of the agriculture and rural life styles while paying attention to the mutual promotion between the agriculture and rural life. During the change of the energy-use habit under policy guidance, attention must be paid to interprovincial cooperation. Finally, a reasonable market mechanism should be established to promote energy upgrade. [ABSTRACT FROM AUTHOR]

Most contemporary urban cellular automata (CA) models primarily focus on the simulation of urban land expansion, and cannot effectively simulate vertical urban growth. This study addresses this drawback by extending a patch-based urban CA model with a component that can predict the building volumes of an urban land expansion scenario. The proposed model is evaluated through a case study in the Guangzhou-Foshan metropolitan area, China. The horizontal urban growth simulations achieve a mean 'Figure-of-merit' value of 0.1406 at the cell level and an agreement of 97% at the pattern level. The building volume prediction made by the methods of random forest and k -nearest-neighbor has a testing R 2 of 0.90 and a mean percentage absolute error of 22%. The proposed model is applied to the urban growth projections under the shared socioeconomic pathways (SSPs). The results successfully reflect the influences that different SSPs have on vertical urban developments. These results also complement related research of urbanization projections under the SSPs, because most existing studies consider the impacts of horizontal urban growth only. As building volumes and heights are fundamental parameters to urban climate modeling, the ability of the proposed model to project future change in vertical urban developments can support the mitigation of climate change effects on human settlements. • Horizontal and vertical urban growth is simulated by using a patch-based CA model. • RF and k -nn are combined to predict building volumes and yield a high R 2 of 0.90. • The proposed model predicts building volumes and heights for the SSPs. [ABSTRACT FROM AUTHOR]

The reduction of agricultural greenhouse gas emissions relies on farmers' active involvement in mitigation actions. However, little is known about farmers' capability of engaging with climate change mitigation. This study addresses the gap by delineating an actor-centered, capability-based, and multi-dimensional framework of farmers' carbon capability to elucidate how and to what extent farmers are equipped to engage in climate change mitigation. A structural equation model and farm-level data collected from China are used to explore the structural relationships between the carbon capability constructs. The results show that farmers' intrapsychic constructs are pro-environmental, and their cognitive knowledge about pro-climate farming practices is moderate. However, the performance of pro-climate farming is largely not under farmers' behavioral control. Farmers generally have a weak tendency to perform stable pro-climate farming behaviors, while they are slightly more inclined to behave pro-environmentally in social interactions. In addition, farmers' behavioral control capability emerges as the strongest predictor of the behavioral capability of farming, which, in turn, is an essential prerequisite for both the behavioral capability of socializing and influence capability. The findings of this study have important strategic implications for policymakers seeking to reduce agricultural greenhouse gas emissions. • A conceptual framework of farmers' carbon capability is proposed and tested. • Analyses elucidate the aspects in and extent to which farmers are equipped to engage in climate change mitigation. • Pro-climate farming is largely not under farmers' behavioral control. • Farmers' control over pro-climate farming matters to their own behaviors but also to peers' responses. [ABSTRACT FROM AUTHOR]

Promoting technology development co-operation is particularly relevant while addressing global climate change or regional pollution. Investors may contribute to increasing environmental-related patents, which may help to improve the quality of the environment as long as supported by proper regulations and policies. In the quest towards a cleaner environment via the mitigation of climate change, this study investigates the relationship between technological innovation, income level, renewable energy and carbon emissions in both the United States and China. Applying the dynamic auto-regressive distributive lag (DARDL) simulation method revealed varying impacts of regressors on CO 2 emissions in the short-run and long-run. Accordingly, this study empirically confirms that (i) technological innovation reduces carbon emissions in the United States but it is not statistically significant in China. (ii) Renewable energy reduces carbon emissions in both countries. (iii) The impact of income level on emissions decreases from short-run to long-run in both countries. Decision-makers in China should stimulate more effective environmental-related innovations to decrease CO 2 emissions and should permit easy access to environmental-related patents together with reducing its cost of registration. • Investigates the role of green technological innovation in decreasing CO 2 emissions. • Applies the novel Dynamic ARDL simulation. • Green technological innovation reduces CO 2 emissions in the U.S. Only. • Confirms that renewable energy mitigates CO 2 emissions both in the U.S. and China. [ABSTRACT FROM AUTHOR]

In recent years, ozone pollution has attracted wide attention from the scientific community, policymakers and the public. Previous studies have already confirmed the effects of meteorological conditions on regional ozone pollution events in the last two decades. However, due to the lack of historical ozone observations, the relationship of climate variability and ozone pollution has been less discussed. In our study, we use the NCEP/NCAR Reanalysis data and modeled historical surface ozone from CMIP6 (Coupled Model Intercomparison Project Phase 6) to explore the impact of climate variability related to Tibetan Plateau on summertime (June, July and August) ozone in Central China during 1950–2019. The results show that in interdecadal timescale, the annual summertime ozone over Central China is significantly correlated (R = −0.52; P -value <0.05) with the springtime (March, April and May) thermal forcing, indicated by total atmospheric energy (TPE), over Tibetan Plateau. In high TPE years, the East Asian monsoon (southerly wind flow) and vertical ascending motion have been enhanced in summer. It is conducive to both the diffusion of ozone and its precursors and occurrence of cloudy and high humidity weather. These processes lead to lower ozone concentrations up to 6.97 ppb (compared with values averaged during 1950–2019) over Central China. On the contrary, in low TPE years, summertime surface ozone concentrations have been increased by 2.96 ppb (the mean value is 49.00 ppb and the standard deviation is 11.75 ppb for 1950–2019) on average of Central China, due to the weakened East Asian monsoon and weakened vertical ascent, thus the stable weather with low humidity and small near surface wind. After the year 2000, the TPE has increased with a rapid growth rate of 3 × 104 hPa J kg−1 yr−1. However, similar to the reported surface ozone increments based on the modeling results and observations, the CMIP6 summertime surface ozone has shown an increasing trend in the last two decades (0.45 ppb yr−1 and 0.25 ppb yr−1 over Central China and entire China during 1950–2019, respectively). While a decline trend (0.18 ppb yr−1) of ozone from 1980 to 2019 over Central China is calculated after the removal of emission-attributed trend. These results indicate that the ozone increasing trend dependent on the changes of precursor emissions has offset the ozone mitigation attributed to the climate. • Effect of springtime thermal forcing over TP on summertime ozone is revealed. • Thermal forcing over Tibetan Plateau has an interannual to decadal variation. • Historical weather over Asian monsoon region are affected by thermal forcing over TP. • Ozone increases due to emissions has offset the ozone mitigation due to the climate. [ABSTRACT FROM AUTHOR]

• An integrated top-down and bottom-up modeling framework was developed. • Analyze low-carbon pathways for Chinese iron & steel industry towards carbon neutrality. • Both the supply-side and demand-side contributions to decarbonization are explored. • Energy-saving retrofitting technologies help short-term CO 2 emissions reduction. • Breakthrough technologies are crucial in achieving carbon neutrality. Iron and steel production in China contributes to 14% of China's total energy-related CO 2 emissions. Decarbonizing the iron and steel sector will therefore play an important role in achieving the goal of carbon neutrality. This study explored possible low-carbon transition pathways for China's iron and steel industry to achieve carbon neutrality by 2050. An integrated approach was developed that combined a computable general equilibrium model and a bottom-up technology-selection module. The results indicated that although energy-saving technologies can reduce CO 2 emissions in the short term, in the long term, adopting breakthrough technologies (e.g., carbon capture and storage (CCS) and hydrogen-based direct reduction (DR)), increasing the share of scrap-based electric arc furnace (EAF) steel production, and decarbonizing upstream energy-supply sectors will be crucial for climate change mitigation. Hydrogen-based DR could be an effective option for CO 2 emission reduction in scenarios where CCS is not available, with its share increasing to 23%–25% by 2050. System-wide cross-sector decarbonization can help achieve climate targets at lower costs through flexible technology combinations and avoid carbon leakage into upstream energy-supply sectors. [ABSTRACT FROM AUTHOR]

About 3 billion people still rely on traditional sources of fuel. Biomass-based fuels were responsible for more than 4 million deaths in 2012. Household energy consumption is steadily increasing across cities due to the urbanization of rural areas, more economic and travel activities. In this review, Multiple Correspondence Analysis (MCA) and other bibliometric tools were applied to determine the conceptual structure and typological thematic areas of household emissions in urban areas. The current state of knowledge and opportunities towards creating carbon-neutral cities indicated that while most of the research was focussed on cities and regions of developed countries and China, the mitigation activities grouped under three broad heads - reducing emissions, consumption and impact of household emissions. Strong heterogeneity between the urban and rural areas, fuel options and human choices gave rise to fuel-stacking in developing countries. Integrated modelling and inclusion of environmental and human behavioural components into economic models were recognised as emerging fields oriented towards a systems approach. Accessibility and availability of clean energy and clean energy appliances were identified as the biggest challenges. To create carbon-neutral urban areas, integrated modelling should include categorization of carbon policy according to local conditions, analysis of feedback loops, embedded emissions, the global and regional impact of household consumption patterns, and uncertainty associated with mitigation measures. [Display omitted] • Carbon neutral cities should have access equality despite income inequality. • Multiple Correspondence Analysis indicated mitigation research focused on emissions, consumption and impacts. • Integrated modelling and general equilibrium models were the two emerging themes. • Risk, uncertainty, embedded emissions and feedback loops should be integrated into emission models. • Availability and accessibility to cleaner fuels is the biggest challenge for creating carbon-neutral cities. [ABSTRACT FROM AUTHOR]

• Climate-sensitive additive stand biomass models were developed. • The difference in biomass estimations when using the new models at a large scale was quantified. • Forecast combination method reduced the uncertainty from the biomass models. • About $8.3 million carbon services were underestimated using traditional models. • Climate-sensitive stand biomass models were recommended for carbon service accounting. Accurate forest carbon service accounting is essential for climate change mitigation. At present, the knowledge about whether and how climate-sensitive stand biomass models could reduce the uncertainty of forest biomass/carbon estimation is lacking. Hence, the aim of this study is to develop climate-sensitive stand biomass models and quantify their differences. Data containing 539 sample plots of larch plantations in northern and northeastern China were utilized to develop two basic and the corresponding climate-sensitive stand biomass models. Owing to the uncertainty from predictors, the forecast combination method was used to combine the two basic models (FCMs) and the two climate-sensitive models (CS-FCMs) and to quantify the difference in biomass estimations at the plot and regional scales. Results showed that the adjusted R 2 values of the stand biomass models were greater than 0.85 and the relative root mean square errors ranged from 5.51% to 22.62%. The CS-FCMs produced more accurate biomass estimates than the FCMs. The difference in biomass estimations derived from biomass models with and without climatic variables was 411,549 tons or 0.27% at the regional scale, but the carbon value difference amounted to about $8.3 million. This study underlined the importance of accurate carbon accounting based on climate-modified stand biomass models for forest carbon management. [ABSTRACT FROM AUTHOR]