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The East Asian summer monsoon (EASM) was extremely strong in 2018, which substantially affected surface ozone (O3) in China. Taking 2018 and the average synthesis of 2003 and 2010 to represent the strong and weak EASM cases, respectively, GEOS-Chem with constant anthropogenic emission was employed to investigate the impact of the EASM on surface O3 in the east of China. Simulations show that surface O3 decreased in the northeast and the eastern coast of China and increased in most of the remaining regions during strong EASM. The difference in surface O3 between strong and weak EASM was around −15~7 ppbv. After analyzing relevant meteorological fields, it is found that the decrease in northeast China was mainly attributed to the large increase in vertical upward transport. The considerable decrease in the Huang-Huai-Hai region depended on the dilution and diffusion of eastward anomalous horizontal circulation. The increase in Hunan-Hubei-Guangdong Province was largely due to input from the north. In addition, the vast areas between the Yangtze River and the Yellow River were supported by higher temperatures and stronger shortwave solar radiation that promoted photochemical reactions. The reasons for changes in Shanxi-Sichuan-Yunnan Province were relatively more complex and thus require more in-depth exploration. [ABSTRACT FROM AUTHOR]

The "low-hanging fruits" measures that easily and quickly reduced pollution and energy intensity over the past decades are now giving rise to issues. Cleaner production may provide new opportunities to gain the "high-hanging fruits"—more challenging or costly actions that have greater environmental and energy benefits but require advanced technologies or management for implementation. This study provides empirical evidence on the effects of cleaner production audits (CPAs) on Chinese manufacturing firms' total factor energy efficiency (TFEE), whose enhancement synergizes climate mitigation and green productivity growth. The study analyzes the effects of CPAs by employing a staggered difference-in-difference strategy combined with propensity score matching to compare samples of treated and untreated industrial firms for the period of 2000–2014. The findings show that regulated firms experience a 10.4% increase in TFEE. The contributions of green pure technical efficiency and green technical progress are 7.9% and 2.7%, respectively. Additionally, non-heavy polluters, small firms, and private firms demonstrate the greatest improvements in TFEE. However, CPAs do not significantly impact the TFEE of firms with high dependence on fossil energy. Finally, the mechanism analyses demonstrate that inner resource allocation optimization may be the main solution for improving TFEE by enhancing green pure technical efficiency. Green technological innovations in energy alternatives are the most promising paths for increasing TFEE by promoting green technical progress. These findings illuminate how manufacturing firms pick the "high-hanging fruits" of energy efficiency in more cost-effective ways and suggest useful insights for cleaner production promotion. • Explores how cleaner production audits (CPAs) impact firm total factor energy efficiency (TFEE). • Resource allocation optimization may be the main path for improving TFEE. • Alternative energy production innovations are cost-effective paths for increasing TFEE. • Different firms' TFEE vary distinctively based on CPAs. • CPAs do not significantly impact TFEE of firms with high dependence on fossil energy. [ABSTRACT FROM AUTHOR]

Technological innovation is an important solution that can help improve environmental efficiency. However, the role of technological renovation in enhancing environmental efficiency has been ignored. This study provided initial evidence of the effects of cleaner production audits in China on manufacturing firms' environmental efficiency, which was measured by the emissions of sulfur dioxide and chemical oxygen demand per total output. Cleaner production audits were used as exogenous shocks. Their impact was estimated using the staggered difference-in-difference method combined with samples of ever-treated or never-treated firms using propensity score matching. The findings showed that firms that conducted cleaner production audits (vs. those that did not) experienced 4.7% and 11.9% reductions in the emission intensities of sulfur dioxide and chemical oxygen demand, respectively. Cleaner production audit implementation significantly improved firms' environmental efficiency. Additionally, a heterogeneous analysis showed that non-heavy polluters, small and medium-sized firms, and non-state-owned firms demonstrated the most improvement in environmental efficiency. Finally, the mechanism analysis results showed that firms' technological renovation in the production process is the main solution for improving environmental efficiency. This is a feasible and cost-effective way of reducing resource consumption and pollutant emissions. Accordingly, a cleaner production audit plan for different countries should be formulated with a focus on technological renovation in the production process. It should entail clean-cut incentives to stimulate firms to perform technological innovation, thereby continuously improving firms' environmental efficiency. This study sheds light on the environmental impact of cleaner production audits and regulated firms' choices between technological renovation and innovation. [Display omitted] • Effects of cleaner production audits on firms in China are investigated. • Cleaner production audits significantly improve firms' environmental efficiency. • Technological renovation in production processes improves environmental efficiency. • It is a cost-effective way to reduce resource consumption and pollutant emissions. [ABSTRACT FROM AUTHOR]

Highlights • The implementation of the prohibited grazing policy has achieved remarkable ecological benefits. • Farmers of different types had different adaptation perceptions. • Farmers of different adaptation perceptions choices of adaptation strategies also varied. • The main factors that influenced farmers' adaptation strategies also included livelihood capital and farmers' perception of the policy. Abstract Due to long-term human activities, grassland ecosystems have been severely damaged. To protect grassland ecosystems, the prohibited grazing policy (PGP), a grassland ecological protection policy, was instituted for Chinese grasslands in 2002. However, it is unknown whether farmers have effectively adapted to the PGP. The adaptability of farmers to this policy has directly influenced the effective implementation of the policy and the sustainable development of the ecosystem. Previous research on adaptability has not focused on the adaptation to political change. This article uses a case study in Northwest China to investigate the adaptability of farmers to the policy. First, we study the restoration status of ecosystems. In addition, this paper studies the perceptions regarding farmers' adaptability to the policy and explores the adaptation strategies of different types of farmers. Finally, this paper discusses the main factors that influence farmers' choice of adaptation strategies. The implementation of the PGP has achieved remarkable ecological benefits. Farmers of different types had different adaptation perceptions, and their choices of adaptation strategies also varied. In addition to the farmers' perception of the policy, the main factors that influenced farmers' adaptation strategies also included livelihood capital. [ABSTRACT FROM AUTHOR]

Fine particulate matter (PM 2.5) and ozone (O 3) are the two important pollutants because of their harmfulness. In addition to pollution emission level and location, meteorological factors affect the distribution of extreme pollution, so analysing the weather fields under extreme pollution is of great significance to predict extreme pollution. In this study, based on PM 2.5 and O 3 atmospheric composition monitoring data from China National Environmental Monitoring Center (CNEMC) Network and daily meteorological data from Version 2 of Climate Forecast System of National Centers for Environmental Protection (NCEP) Climate Forecast System, the distribution types of wintertime PM 2.5 and summertime O 3 pollution in China from 2015 to 2019 were classified with Empirical orthogonal function (EOF) method, and the types of weather characteristics were analyzed, respectively. The results showed that the distribution of extreme pollution and the distribution of meteorological fields had a good correspondence. High PM 2.5 was accompanied with high relative humidity (RH), higher temperature (T), low pressures (P) and low wind speeds (W). The two maximum centers of correlation coefficients between PM 2.5 and the atmospheric circulation field were located on Siberia and the east of Japan. High O 3 was accompanied with dry environments and higher temperature. O 3 contaminated areas were accompanied with low pressures, while the correlation with wind speeds were not so significant. Ocean cyclones seriously affected O 3 pollution levels in the south and along the coast. The two maximum centers of correlation coefficients between O 3 mass concentration and 500 hPa geopotential height were located on the east of Lake Baikal and southern China. The relevant indexes established in the key areas had all passed the significance test and had an indicative significance for forecasting the pollution level. We believe that the apparent correlations between PM 2.5 (O 3) and RH, T, as well as W related to the external factors associated with the life cycle of midlatitude mesoscale weather system, rather than the underlying direct internal cause. • Different pollution patterns of PM 2.5 and O 3 are obtained by EOF. • RH, T, P and W fields corresponding to different pollution distributions are presented. • Meteorological conditions are external factors that affect the area and frequency of pollution. • The key area of 500 hPa affecting PM 2.5 is on Siberia and the east of Japan. • The key area of 500 hPa affecting O 3 is on the east of Lake Baikal and southern China. [ABSTRACT FROM AUTHOR]

The positive trend of tropospheric column ozone (TCO) in China has been confirmed by numerous observations, particularly in the rapidly developing city clusters such as Beijing-Tianjin-Hebei (BTH), the Yangtze River Delta (YRD) and the Pearl River Delta (PRD). An unignorable but poorly known function may be played by the Brewer-Dobson circulation (BDC) and the Hadley circulation (HC), both of which are in their strengthening phase. This study discusses their connection to TCO in these three city clusters based on a novel and powerful causal analysis method Convergent Cross Mapping (CCM). It revealed that both BDC and HC exerted substantial causal effects on the variations of the TCO in BTH, the YRD, and the PRD. The upwelling moving northward in the summer substantially lowered TCO in the PRD, contributing to the difference in the TCO annual cycle characteristics between northern and southern China. Besides, CCM distinguished that hemispheric HC impacts TCO greatly more than total HC, and the most essential branches of BDC were stratospheric or shallow branches. The BDC and HC indices determined by CCM were used for building a multiple linear regression model, which assessed their importance for long-term changes in regional TCO. The intensity of BDC is the most important influencing factor in each region, particularly in the YRD. BTH is mainly affected by the intensity of the two meridian circulations. The influence of the widths of meridional circulation upwellings on TCO in the PRD cannot be ignored. Furthermore, TCO displayed significant positive trends during 2005–2020, with rates of 2.3 ± 0.4, 2.5 ± 0.4, and 2.7 ± 0.5 DU/decade in BTH, the YRD, and the PRD, respectively. • BDC and HC contribute to the different annual cycle patterns of TCO in northern and southern China. • Hemispheric HC impacts TCO greatly more than total HC. • The upwelling moving northward in the summer substantially lowered TCO in the PRD • TCO showed positive trends of around 2.5 DU/decade in China from 2005 to 2020 [ABSTRACT FROM AUTHOR]