China's national emissions trading scheme (CN ETS) is the world's largest carbon market in terms of covered emissions, yet rigorous empirical evidence on its mitigation effectiveness remains limited. Using a balanced panel of 1,957 thermal power units from 2018 to 2024, this study estimates the causal impacts of compliance pressure under the CN ETS on CO2 emissions. Units with allowance deficits reduced CO2 emission intensity by 0.8% and total emissions by 3.5%. Emission reductions are concentrated among small coal-fired units and are driven by efficiency improvements, higher heat supply ratios, and improved fuel quality. In contrast, the impacts on large coal-fired units are limited. Greater intensity reductions are observed among local state-owned and private firms, captive plants, non-pilot units, and technologically less advanced units. Overall, the intensity-based design provides limited incentives to curb output among low-emission-intensity units, suggesting the intensity-based mechanism functions as a transitional arrangement toward a cap-and-trade system.

City-scale, source-resolved methane (CH4) inventories are needed in China because prefecture-level cities differ in energy systems, agricultural activities, and waste management. These differences lead to divergent dominant sources and mitigation needs. Yet city-level CH4 inventories across the energy, agriculture, and waste sectors remain scarce. This scarcity limits policy design, targeting, and evaluation. Here we develop a harmonized, annually consistent, multisector, source-resolved CH4 inventory for 339 prefecture-level cities in China during 2018-2024. We further use Logarithmic Mean Divisia Index (LMDI) driver attribution and scenario analysis to examine recent emission drivers and explore possible mitigation pathways. Over this period, national anthropogenic CH4 emissions increased by 2.61%, with regional heterogeneity shaped by differences in energy dependence, livestock management, and waste treatment. LMDI decomposition identifies economic activity as the dominant positive driver. Emission-intensity effects alternated between mitigating and reinforcing impacts, while structural effects were minor and population effects varied across space and time. Scenario simulations suggest that integrated multisector strategies could reduce national CH4 from 61.69 Mt in 2024-51.26 Mt in 2030 and 22.26 Mt in 2060, corresponding to a 63.9% reduction. These reductions are primarily driven by energy-sector measures, complemented by improvements in agriculture and waste management. This data set and attribution inform city-specific mitigation planning and source targeting, support monitoring, reporting, and verification, and provide a baseline for benchmarking progress toward national methane targets.

China is the world's largest source of methane (CH4) emissions and has signalled its intention to incorporate methane into its climate commitments. Designing effective methane-mitigation strategies requires robust estimates of up-to-date emissions, particularly when the pronounced spatial heterogeneity and temporal variability of each emission source are considered. However, there is currently an absence of source-level, up-to-date and dynamic CH4 emission estimations in China, constraining the formulation of measurable targets. In this study, we present the Chinese Methane Emissions Database (CMED), a nationwide, source-level, monthly emission inventory covering the period 2018-2024. The CMED provides a comprehensive account of anthropogenic CH₄ emissions in China. Uncertainty analysis of the CMED indicates that CH₄ emission estimates fall within an acceptable range (±3.57%), underscoring the robustness of the dataset. This comprehensive dataset enables more accurate analyses by providing integrated, source-level and temporally explicit information, offering critical support for policy evaluation under China's new round of Nationally Determined Contributions climate commitments released in 2025.

China's national emissions trading scheme (ETS), announced in 2017, has become the largest carbon market worldwide, operating alongside pre-existing regional pilots. However, detailed assessments regarding the newly constructed national ETS, particularly in comparison with the regional pilots, remain limited. Using unit-level monitoring data from China's power sector and combining intermediary and moderate models, this study investigates the carbon mitigation impact of China's national ETS relative to pilot ETSs. We find that while both the national and pilot ETSs significantly reduce carbon intensities, the effect was more pronounced in pilots. A mechanism behind this reduction is the improvement in fuel quality, as evidenced by a decrease in carbon content. Regional economic growth and a higher share of industrial activity appear to offset the policy's overall effectiveness. Heterogeneity analysis shows that the mitigation effects were greater in smaller and older units compared to their larger or newer counterparts. Our unit-level empirical evaluation of China's national ETS not only advances theoretical understanding of emissions trading mechanisms but also provides actionable insights for refining or establishing carbon market policies in emerging economies.

In the first compliance phase, China's national emissions trading scheme (ETS) became the world's largest carbon market, regulating 4.5 billion tons of carbon emissions annually from 2019 to 2020 (2.8 times the EU ETS level). However, an ex post analysis of this market is lacking. Using unit-level monitoring and order-specific trading data, we explore the performance of China's national ETS and the responses of regulated power-generating plants. We find tightened supervision, profitable incentives, stable but trade-sensitive prices, and overall compliance, with 93.9% of units and 99.6% of obligations compliant. We also observe reductions in carbon intensities and emissions of 2.46%-3.13% and 0.86%, respectively, despite 1.63% production growth. Most abatements come from enhancing energy efficiency (57%), improving fuel quality (31%), retiring outdated units, and promoting cleaner energy (particularly biomass). Our results highlight the effectiveness of China's national ETS and the potential for ongoing renovations and unit-targeted planning.

Using benchmarking as the free allowance allocation method, China has constructed the world's largest national carbon emissions trading system (ETS). Yet in its initial phase, overallocation led to modest carbon price declines, and limited research has assessed the performance of the current allocation approach or proposed improvements. To address this gap, we propose an optimization framework, involving unit-specific information, to specifically delve into the performance and future enhancement of the existing policy. Using this framework, we estimate unit-level emissions, identify the disadvantages of the existing benchmarking method, and optimize benchmarks within the current policy framework in the four typical provinces. The results indicate that the optimized benchmarks, compared to the existing policy, align better with targeting high-emitting outdated units, allocating 3.62 % surplus allowances to gas-fired units (versus only 0.99 % for actual allocation) and 1.69 % deficit (versus otherwise 12.64 % surplus) to unconventional coal-fired units. Additionally, we suggest two enhancements, the removal of the heat supply ratio parameter and a refinement of the grouping approach, to improve the existing allowance allocation method. These findings provide valuable guidance for future ETS construction in China and the experiences of China's first-phase national ETS offer insights for other countries seeking to establish their own ETS.

As a major source of carbon emissions, the civil aviation sector needs a feasible path for low-carbon transition. Owing to the dynamics of travel demand in China, the spatial patterns of aviation emissions are difficult to foresee or simulate in scenario analysis. To address this issue, we predicted the spatial patterns of aviation carbon emissions in China at the city level using projected gridded population data and power law model. The results show that China's civil aviation sector will have a cumulative emission abatement potential of 7027 million tons from 2020 to 2060 if all abatement measures can be implemented. The contribution of individual cities was quantified based on expected changes in population, airport planning, and economic development. Megacities and metropolitan cities will contribute to 58.1 % and 26.2 % of the total emission abatement, respectively. The eastern, central, and western regions of China will contribute to 64.2 %, 15.8 %, and 20.0 % of the total abatement, respectively. The abatement potentials before and after 2040 are expected to account for 20.0 % and 80.0 % of the whole from 2020 to 2060. Therefore, some regions and cities can be regarded as key or pilot areas to implement abatement measures. Finally, policy implications of the results are presented.

The low-carbon development of air transport industry is of great significance for China to achieve the commitment of carbon peak and carbon neutrality goals. In order to improve the basic data of aviation CO2 emissions, this study continuously collected full flight information in China from January 2017 to December 2020, and established a flight information database and an aircraft-engine parameter database. On the basis of IPCC's Tier 3B accounting method, this study established a long-term aviation CO2 emissions inventory of China from 2017 to 2020 by calculating and accumulating CO2 emissions of each flight. And aviation CO2 emissions of various provinces and cities in China were calculated combined with spatial allocation method. The results showed that aviation CO2 emissions in China was 104.1, 120.1, 136.9, and 88.3 Mt in 2017, 2018, 2019, and 2020, respectively, with annual growth rates of 15.4%, 14.0%, and-35.3% in 2018, 2019, and 2020, respec-tively. Affected by the COVID-19 pandemic, aviation CO2 emissions in all 31 provinces and 93% of cities decreased in 2020 compared with 2019. China is in the stage of rapid development of air transport industry, and aviation fossil energy consumption and CO2 emissions have continued to grow in recent years.

In China, road traffic carbon emissions and their share in total carbon emissions have significantly increased. In the context of double carbon, the Beijing-Tianjin-Hebei region, the largest urban agglomeration in northern China, is receiving more and more attention. Due to the unbalanced development in Beijing-Tianjin-Hebei urban agglomeration, this thesis presents three computational models to calculate road traffic carbon emissions for large, medium-sized, and small cities and intercity traffic arteries based on the road network. The results show that in 2019, Beijing has the highest road carbon emissions reaching 19.91 million t CO2 which is almost three times that of Shijiazhuang, the capital city of Hebei province. Dwellers' commuting usually results in an increase of 2.9%, 3.3%, and 4.5% on weekdays compared with weekends for Tianjin, Shijiazhuang, and Beijing, respectively. As for the intercity road, the daily traffic flow is about 1.92 million vehicles, leading to total carbon emissions of 22.97 million t CO2. In addition, the reduction potential of carbon emissions in Beijing is evaluated. If the average road speed is increased to 0.9V(f) (road design speed) during the morning rush hour in Beijing from 7 a.m. to 8 a.m., the road emission reduction could reach 57.85%.