As one of China’s most common vegetation types, grasslands comprise about 27.5% of its terrestrial area and 41% of its carbon storage. Since climate change (CC) and human activities (HA) have a great effect on grasslands, quantifying the contributions of CC and HA on grassland net primary productivity (NPP) is crucial in understanding the mechanisms of grassland regional carbon balances. However, current approaches, including residual trend, biophysical model and environmental background-based methods, have limitations on different scales, especially on the national scale of China. To improve assessment accuracy, modifications to the environmental background-based method were introduced in calculating the CC and HA contributions to the actual NPP (ANPP). In this study, the grassland ANPP in national nature reserves was defined as the environmental background value (PNPP), which was only affected by CC and without HA. The pixel PNPP outside the nature reserves could be replaced by the pixel PNPP in the nature reserve with the most similar habitat in the same natural ecological geographical division. The impact of HA on grassland ANPP (HNPP) could be identified by calculating the difference between PNPP and ANPP. Finally, the contributions of CC and HA to ANPP changes were assessed by the trends of ANPP, PNPP, and HNPP. The results showed that the average grassland ANPP significantly increased from 2001 to 2020. CC contributed 71.0% to ANPP change, whereas HA contributed 29.0%. Precipitation was the main contributor to grassland growth among arid and semi-arid regions, while temperature inhibited productivity in these areas. HA was the major cause of degradation in China’s grasslands, although the effects have declined over time. The research could provide support support for government decisions. It could also provide a new and feasible research method for quantitatively evaluating grasslands and other ecosystems.

The transportation sector is a major source of greenhouse gases and air pollutants, and it has a crucial effect on the synergistic reduction of NO_x and carbon. In order to find the energy-efficient vehicle technologies with the highest net reduction potential and lowest net reduction cost over the life cycle, this study traced the CO₂ and NO_x emission streams of 33 energy-efficient technologies, hidden in the supply chain during the production phase, through structural path analysis, and measured the emission reductions during the use phase using the emission factor method. Moreover, we applied structural decomposition analysis to quantify the three main drivers, including emission intensity, industrial structure, and final demand, of changes in CO₂ and NO_x emissions from 11 transport subsectors during 2012–2018. Results indicate that CO₂ emissions of the transport sector more than doubled from 2012 to 2018; however, the influence of NO_x was less significant. The final demand of the road subsector was the most significant driver contributing to CO₂ emission changes, with an increase of 109.27 Mt. The emission intensity of road transportation caused the greatest mitigation effect on NO_x emission changes, with a decrease of 1902 Kt. The findings of the scenario analysis demonstrate that the most efficient action of the pure electric technology for passenger cars reduces 20.92 Mt NO_x emissions, and the parallel hybrid technology for heavy trucks offers the greatest cost effectiveness with a net abatement of 2577 Mt CO₂ over its life cycle. Consequently, the aggressive development of new energy technology has become a prerequisite strategy to synergistically reduce CO₂ and NO_x emissions.

The transportation sector has a significant impact on the synergistic reduction of CO₂ and pollutants. Using a structural path decomposition, we reveals the direct and embodied CO₂ and NOx emissions from the transportation sector triggered by key supply chain pathways. Meanwhile, the emission abatement potential and economic costs of 33 vehicle specific abatement technology options are analyzed based on the input-output analysis for life cycle assessment. The results show that most of the vehicle technology options can reduce CO₂ and NOx emissions while saving economic costs. Among these technologies, both the pure electric technology for passenger cars and the parallel hybrid technology for heavy-duty trucks have high abatement potential. Compared to costly pure electrification technologies for passenger cars, parallel hybrid technologies for heavy-duty trucks offer the highest economic benefits as well as a better driving mileage. Therefore, hybrid heavy-duty trucks will be a more comprehensive solution in the near future.

Understanding the multisectoral and multiregional cooperation which coordinates the relationship between different government actors and integrates their policies is essential to effectively address increasing regional air pollution. Although the literature on effects of polices is rapidly expanding, little is known about the actual extent of policy linkage of multisector and multiregion, resulting in policy conflicts and duplications. Using 13486 policy documents in China from 2000 to 2018, we combine machine learning methods with social network analysis to investigate the policy content and linkage in central departments and local departments. We find that, firstly, the coordination of central departments is constantly improving, mainly focusing on the Comprehensive Control and the Publicity Guide, with little attention to market-oriented measures. Secondly, since local governments have similar policy foundations in Emergency Management, Total Amount Control, Dust Control, and Moving Pollution Control, they are able to cooperate in these aspects, even when there are differences in local regulations. This paper provides suggestions for the further coordination of the central government, as well as the direction of policy integration for local governments.