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Recent decades witnessed the increase in production and uses of HCFC-22 (chlorodifluoromethane, CHClF 2 ) and its alternative, HFC-410A (a blend of difluoromethane and pentafluoroethane), in China in response to the booming of room air conditioners (RACs) for both domestic use and exports. HCFC-22 is an ozone-depleting substance under the Montreal Protocol, while both HCFC-22 and HFC-410A are greenhouse gases (GHGs). This study provides a most comprehensive consumption and emission inventory of refrigerants emissions (HCFC-22 and HFC-410A) from RAC sector during 1995–2014, for the first time. Our estimates show that HCFC-22 emissions increased from 0.7 Gg/yr in 1995 to 48.2 Gg/yr in 2014. The accumulative emissions contributed to global total HCFCs emissions by 4.4% (3.3%–6.1%) CFC-11-equivalent (CFC-11-eq) and 5.4% (4.1%–7.5%) CO 2 -equivalent (CO 2 -eq) during 1995–2012. If left uncontrolled, accumulative emissions of HFC-410A will be12.4 (7.1–20.2) CO 2 -eq Pg during 2015–2050, which can offset the global climate benefits achieved by the Montreal Protocol. The HFC-410A emissions from China's RAC sector are estimated to be of importance to both global HFCs emissions and China's GHG emissions. Further, we probed the emission mitigation performances of the current 2014 North American Proposal scenario and a modified more ambitious scenario. The emissions of two mitigation scenarios are only 28% and 22% of the emissions without mitigation actions, respectively. This study is the first effort to map the transition of eliminated substance HCFC-22 and its alternative HFC-410A in RAC sector. Therefore, alternative chemicals should be scrutinized with cautions before they are promoted and applied. [ABSTRACT FROM AUTHOR]

Methyl Chloride (CH 3 Cl) is the largest source of stratospheric chlorine, which has a significant impact on the depletion of the stratospheric ozone layer. Detailed information on anthropogenic CH 3 Cl emissions in China is still lacking. This study establishes a comprehensive bottom-up inventory of anthropogenic CH 3 Cl emissions in China during 2000–2020. Results show that China's anthropogenic CH 3 Cl emissions have increased significantly, from 34.1 ± 11.6 Gg/yr (gigagrams per year) in 2000 to 128.5 ± 26.5 Gg/yr in 2018 with a slight decrease to 124.9 ± 26.0 Gg/yr in 2020. The main sources of anthropogenic emissions of CH 3 Cl in China are chemical production (37.1%), solvent use (35.4%), and coal combustion (13.6%) in 2020. China's contribution to global anthropogenic emissions of CH 3 Cl reached almost 50%. Moreover, the ratios of CH 3 Cl CFC-11-eq emissions relative to emissions of ozone-depleting substances (ODSs) controlled under the Montreal Protocol in China have increased from 0.8% in 2000 to 11.6% in 2020 and are estimated to continue increasing in the future. In summary, China's anthropogenic CH 3 Cl emissions have shown an increasing trend in the past two decades, made a huge contribution to the total global anthropogenic emissions, and presented a potential increasing impact on the depletion of the ozone layer and global warming. [Display omitted] • A bottom-up anthropogenic emission inventory of CH 3 Cl is established. • China's anthropogenic CH 3 Cl emissions increased rapidly during 2000–2020. • Chemical production and solvent use are the main CH 3 Cl emission sources in China. • The contribution of China's anthropogenic CH 3 Cl emissions is non-ignorable. [ABSTRACT FROM AUTHOR]

As apanoramic overview of the multipronged national-scale regulations of China to synchronously decelerate climate change and improve air quality, this study pores through a constellation of China's strategies aimed to obtain coinstantaneous reductions in the emissions of atmospheric pollution and greenhouse gases (GHGs). These strategies, inclusive of afforestation and silviculture, ultra-low industrial emissions, energy structure reform, renewable energy development, household emission reductions, transportation emission control, and shutdown of cryptocurrency mining, have vouchsafed China new pragmatic dimensions in pursuit of its climate goals and have established a roadmap to bide time for the future. Here we show blow-by-blow the pros and cons of these pathways to illustrate the reasons why they best serve China's long-term targets and dovetail with China's geopolitical realities. Because of the interactions between air pollutants and GHGs, cooperatively reducing the emissions of both air pollutants and climate change gases have mutual benefits and are efficacious for the enhancement of air quality and mitigation of global warming. [ABSTRACT FROM AUTHOR]

1-Chloro-1,1-difluoroethane (HCFC-142b) was both ozone depleting substance under restriction of the Montreal Protocol on Substances that Deplete the Ozone Layer ( Montreal Protocol) and potent greenhouse gas with high GWP. Controlling its emissions in China will contribute to both mitigating climate change and protecting ozone. A national emission inventory of HCFC-142b for China during 2000-2012 was established and projected to 2050 based on the 2006 IPCC Guidelines for National Greenhouse Gas Inventories and the Montreal Protocol, showing that (i) in contrast to the downward trend revealed by existing researches, HCFC-142b emissions kept increasing from 0.1 kt/y in 2000 to the peak of 14.4 kt/y in 2012, making China a crucial contributor to global HCFC-142b emissions and (ii) for future emission projections, a continuous increase from 14.9 kt/y in 2013 to 97.2 kt/y in 2050 was anticipated under the business-as-usual (BAU) scenarios, while a reduction of about 90% of the projected BAU emissions would be obtained by fulfilling the Montreal Protocol, namely an accumulative mitigation of 1578 kt HCFC-142b from 2013 to 2050, equal to 103 kt ODP and 3504 Tg CO emissions. Emissions from each province in 2012 were also estimated to identify key emission areas. Among the 31 mainland provinces in China (Hong Kong, Macao, and Taiwan were not included), Jiangsu, Zhejiang, Shandong, and Guangdong had the highest emission rates in 2012 (2.06, 1.85, 1.52, and 1.04 kt/y, respectively); Zhejiang, Jiangsu, and Shanghai exhibit the strongest emission strength (0.83, 0.59, and 0.54 t/km, respectively), much higher than the average national level of 0.33 t/km. [ABSTRACT FROM AUTHOR]

China has shut down and abandoned a substantial number of coal mines since 1999, which have been releasing methane (CH 4) for many years. However, the characteristics of China's abandoned mine methane (AMM) emissions are still unclear; this is a concerning knowledge gap because coal mines are the largest contributor to China's anthropogenic CH 4 emissions. This study used two methods to estimate China's historical AMM emissions over the past 40 years (1980–2020) and to project its AMM emissions to 2060 which is the target year for China's carbon neutrality goal. The results show that China's AMM emissions increased substantially from 0.11 ± 0.03 million tons per year (Mt/yr) (3.1 ± 0.84 Mt/yr CO 2 -eq) in 1980 to 4.7 ± 0.94 Mt/yr (131 ± 26 Mt/yr CO 2 -eq) in 2020. An accelerated growth rate was found during 1998 – 2005, with AMM emissions rapidly increasing by approximately three times, which was consistent with the high number of mine shutdowns. In 2019, we found that AMM emissions had become the fourth largest anthropogenic source in China, higher than the national anthropogenic CH 4 emissions of individual United Nations Framework Convention on Climate Change Annex I countries excluding the United States of America and the Russian Federation. If unabated, China's AMM emissions are projected to peak at 8.7 ± 2.6 Mt/yr in 2040 and reach approximately one-third of China's anthropogenic carbon dioxide emissions in 2060. This study reveals that understanding AMM emissions can help more accurately quantify China's total CH 4 emissions and guide their future mitigation. • Methane emissions from China's abandoned coal mines from 1980 to 2020 were calculated. • During 1980–2020, there were substantial AMM emissions in China. • AMM emissions have become the fourth largest anthropogenic source of methane. • China's AMM emissions are equivalent to one-third of the China's CO 2 emissions in 2060, under a carbon-neutral scenario. [ABSTRACT FROM AUTHOR]