Spatio-temporal evolution and its policy influencing factors of agricultural land-use efficiency under carbon emission constraint in mainland China.

In the context of the vision to reach peak carbon dioxide emissions before 2030 and achieve carbon neutrality before 2060, Mainland China's agricultural development will face strict carbon constraints. This paper analyzes the agricultural land-use efficiency of Mainland China's agriculture under carbon emission constraint from 1996 to 2020, based on the unexpected super SBM (Slack-based measure)-Undesirable DEA, Malmquist index model, and quartile division-GIS method. The results show that: from 1996 to 2020, the agricultural output value per land and grain output per land show an upward trend, and the agricultural carbon emissions per land of most provinces show an increasing trend and larger emissions. The agricultural land-use efficiency in Mainland China rises first and then decreases, and technological progress is the decisive path to improving the agricultural land-use efficiency in Mainland China. The average MI in the prominent grain-selling area during 1996-2020 was as high as 1.071, which was significantly higher than that in the prominent grain-producing area (1.039) and the balance area (1.030). The improvement of agricultural land-use efficiency is mostly due to technological progress, but the instability of technical input and management in land use. To improve agricultural land-use efficiency in Mainland China, we should pay attention to the precise policy formulation of low-carbon and high-quality development and strengthen government investment in the difference between space resource endowment and development status.

Assessing the possibility of China reaching carbon emission peak by 2030 in the context of the COVID-19 pandemic.

At this stage, it is an important goal for China to solve environmental problems to limit the carbon emission peak by 2030 and then to lower its quality gradually thereafter. The outbreak of the COVID-19 pandemic in 2020 seriously impacted all aspects of China's social economy and brought many uncertainties to the realization of the carbon emission peak. Based on the fact, it has important theoretical and practical significance to take the problem of China's carbon emissions during the COVID-19 as the research object. Thus, this paper analyzes the current situation of China's CO2 emissions and finds out that in the context of ongoing COVID-19 response, stimulated by China's economic stimulus policies, CO2 emissions decrease firstly and then gradually rebound. On this basis, the paper constructs a dynamic model of China's CO2 emission system to simulate the change in China's CO2 emissions under different economic stimulus policies. The relevant simulation results demonstrate the following: (1) China cannot realize the CO2 emission goal by 2030 only by adopting traditional economic stimulus policies. (2) The green economic stimulus policy oriented to the development of clean energy will rebound China's CO2 emissions in the short term, but it can effectively reduce CO2 emissions in the long run. The most important factors affecting CO2 emission reduction are industrial energy consumption and industrial structure, while the energy power generation structure and the transportation structure have a relatively weak impact on the emission reduction effect. (3) The green economic stimulus policy combined with economic stimulus measures and a variety of low-carbon measures can enable China to peak CO2 emissions before 2030, with a peak value of 11.059 billion tons. In general, green economic stimulus policies can achieve a win-win situation for China's economic recovery and carbon emission peak.

Global evaluation of carbon neutrality and peak carbon dioxide emissions: current challenges and future outlook.

With the acceleration of urbanization and industrialization, carbon neutrality and peak carbon dioxide emissions have become common sustainability goals worldwide. However, there are few literature statistics and econometric analyses targeting carbon neutrality and peak carbon dioxide emissions, especially the publication trends, geographic distribution, citation literature, and research hotspots. To conduct an in-depth analysis of existing research fields and future perspectives in this research area, 1615 publications from the Web of Science Core Collection, between 2010 and 2020, were evaluated by using three analysis tools, under the framework of the bibliometrics method. These publications are distributed between the start-up (2010-2015) and the stable development (2016-2020) phases. Cluster analysis suggests three areas of ongoing research: energy-related carbon emissions, methane emissions, and energy biomass. Overall, future trends in this field include cumulative carbon emissions, the residential building sector, methane emission measurement, nitrogen fertilization, land degradation neutrality, and sciamachy satellite methane measurement. Finally, this paper further examines the most comprehensive coverage of nitrogen fertilization and the most recent research of the residential building sector. In view of the statistical clusters from 1615 publications, this paper provides new insights and perspectives for climate-environment-related researchers and policymakers. Specifically, countries could apply nitrogen fertilizer to crops according to the conditions of different regions. Additionally, experiences from developed countries could be learned from, including optimizing the energy supply structure of buildings and increasing the use of clean energy to reduce CO2 emissions from buildings.

[Evolution Characteristics and Driving Forces of Carbon Dioxide Emissions and Sinks in the Pearl River Delta Region, China].

With the rapid economic and population growth, the Pearl River Delta(PRD) Region is one of the regions in China under the greatest pressure to be carbon neutral. This study analyzed the historical evolution characteristics of the carbon dioxide(CO2) emissions and sinks from 2006-2020 and identified the key drivers of the CO2 emissions and sinks based on the exponential decomposition method. The results showed that:① from 2006 to 2020, the total carbon emissions in the PRD Region increased from 218.22 million tons to 366.30 million tons, showing a fluctuating and rising evolution characteristic, with an overall increase of 67.86%. The carbon emission had not yet reached a peak. ② From 2006 to 2020, the total carbon sinks in the PRD Region decreased from 15.67 million tons to 15.53 million tons, showing a trend of fluctuation and decline, with an overall decrease of 0.94%. The carbon sinks were far lower than the carbon emissions, and there was still a large gap between carbon neutrality. ③ The main carbon emission sectors in the PRD Region were the energy sector(40.38%) and industrial sector(26.33%), and the carbon sinks mainly came from forestland(67.92%) and farmland(18.09%). ④ During the period from the "11th Five-Year Plan" to the "13th Five-Year Plan," the main positive driving factors for carbon emissions were economic growth and population size, whereas the main negative driving factor was energy intensity(energy use per unit GDP). However, since the "13th Five-Year Plan," the CO2 emission reduction potential released by reducing energy intensity has been weakening. In the future, the PRD Region needs to address the negative driving potential of the structural adjustment in energy, industry, transportation, and land use. ⑤ During the period from the "11th Five-Year Plan" to the "13th Five-Year Plan," the main positive driving factor for the carbon sink was the green scale, which was conducted by the increase in urban green space during the "11th Five-Year Plan." The main negative driving factor for the carbon sink was the carbon sink coefficient, which was caused by the natural disaster-induced yield reductions in crops with a high carbon sink coefficient, such as rice. Green space structure adjustment should be emphasized in the future. This study can provide scientific support for developing robust carbon-neutral policies in the PRD Region.

Study on the evolution of green innovation city network and its carbon emission effect in Yellow River Basin cities.

Against the background of increasing urbanization rate and intensifying global warming, conflicts between humans and the natural environment continue to arise, and regionalized forms of spatial organization have become an important research direction. This paper constructs a green innovation city network. It empirically tests the evolution process of the green innovation city network and its carbon emission effect by combining the social network approach and the spatial Durbin model. The conclusions are as follows: (1) the strong ties among green innovation city networks are mainly distributed in and around the provincial capital cities and the middle and lower reaches of the Yellow River Basin; the density of green innovation city networks has been strengthened, and the degree centrality and closeness centrality have been improved. (2) The carbon emissions of cities in the Yellow River Basin are generally increasing. Still, the rate of increase is slowing down. The carbon emissions from liquefied petroleum gas show a decreasing trend yearly, and the energy structure tends to improve. (3) The impact of the green innovation city network on carbon emissions mainly comes from its externality's direct and indirect effects; the increase of degree centrality will reduce the total carbon emissions in the region and the network-associated regions.

Modeling and simulation analysis of vehicle pollution and carbon reduction management model based on system dynamics.

The vehicle exhaust pollution has become an important source of air pollutant and CO2 emissions, with the continuous growth of the number of vehicles. Focusing on the increasingly serious problems of vehicle exhaust pollution and CO2 emissions, a management model of vehicle pollution reduction and carbon reduction was established by using system dynamics. Taking Beijing as the case study city, different emission reduction scenarios were designed. Different scenarios are analyzed, and the results reveal the following: (1) Although the carbon tax policy for motor vehicles can play a role in vehicle pollution reduction and carbon reduction to a certain extent, but as the simulation time goes on, the policy effect is gradually weakened. The emission reduction effect of new energy vehicle promotion policy is not significant, and there is a "lag effect" and a "seesaw effect." (2) The science and technology policy has multiple effects of environmental, economic, and health. It can significantly reduce vehicle pollution and carbon emissions, and achieve the peak carbon by 2030. (3) It is not that more policies are better for CO2 emission reduction, and there is a "crowding out effect" in the CS. (4) From the perspectives of long term, the science and technology policy is a more effective way to achieve the co-control of CO2 and PM2.5 and achieve the carbon peaking goal compared with other emission reduction scenarios. These results can provide reference for relevant departments to formulate emission reduction policies and realize the management of motor vehicle pollution reduction and carbon reduction.