Global hydrofluorocarbon (HFC) cumulative emissions will bemore than 20 Gt CO2-equiv during 2020−2060 and have a non-negligible impacton global warming even in full compliance with the Kigali Amendment (KA).Fluorochemical manufacturers (including multinationals) in China haveaccounted for about 70% of global HFC production since 2015, of which about60% is emitted outside China. This study built an integrated model (i.e., DECAF)to estimate both territorial and exported emissions of China under three scenariosand assess the corresponding climate effects as well as abatement costs. Achievingnear-zero territorial emissions by 2060 could avoid 23 ± 4 Gt CO2-equiv ofcumulative territorial emissions (compared to the 2019 Baseline scenario) during2020−2060 at an average abatement cost of 9 ± 6 USD/t CO2-equiv. Under thenear-zero emission (including territorial and abroad) pathway, radiative forcingfrom HFCs will peak in 2037 (60 ± 6 mW/m2) with a 33% peak reduction and 8years in advance compared to the path regulated by the KA, and the radiative forcing by 2060 will be lower than that in 2019. Accelerated phase-out of HFC production in China could provide a possibility for rapid global HFC abatement and achieve greater climate benefits.

After the Kigali Amendment (KA) came into effect, HCFC-22 plants are obliged to limit HFC-23 emissions. Therefore, the study of cost-effective mitigation pathways for HFC-23 is important for the sustainable implementation of KA in China and other HCFC-22 producing countries. This study constructed an inventory of HFC-23 by-production, emissions, and abatement for HCFC-22 plants in China from 2006 to 2020, and predicted the costs and climate benefits of HFC-23 abatement in China's compliance with the KA between 2021 and 2060. Results showed that HFC-23 emissions from HCFC-22 plants in China contributed about 60% of the growth in global atmospheric mole fraction of HFC-23 observed by Advanced Global Atmospheric Gases Experiment (AGAGE) from 2007 to 2020. Furthermore, China's cumulative HFC-23 abatement was about 109 kt (1613 Mt CO2-eq) from 2006 to 2019, accounting for 53% of total by-production, which allowed the global atmospheric mole fraction and radiative forcing of HFC-23 in 2020 to avoid an uplift of 9.2 × 10−9 and 1.7 mW m−2, respectively, contributing to climate change mitigation. Under the baseline of the Kigali Amendment, less emission (LE), and resource utilization (RU) scenarios, the cumulative HFC-23 abatement from 2021 to 2060 would be 683 ± 29 kt (10107 ± 431 Mt CO2-eq), 694 ± 29 kt (10277 ± 427 Mt CO2-eq), and 702 ± 29 kt (10385 ± 426 Mt CO2-eq), respectively. The cumulative net abatement costs for the KA, LE, and RU scenarios would be 5.0 ± 0.2, 2.9 ± 0.2, and −2.7 ± 0.2 billion CNY (2021 prices), respectively. In the future, applying resource utilization technology to reduce HFC-23 emissions can achieve both climate and economic benefits.

Using the source identification and classification methodology described in UNEP standardized toolkit for dioxin releases, combined with research data over the past decade, the production and release of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) from 6 major sectors in China were inventoried from 2003 to 2020, and were projected until 2025 based on current control measures and relevant industrial plans. The results showed that after ratification of the Stockholm Convention, China’s production and release of PCDD/Fs began to decline after peaking in 2007, demonstrating the effectiveness of preliminary control measures. However, the continual expansion of manufacturing and energy sectors, along with the lack of compatible production control technology, reversed the declining trend of production after 2015. Meanwhile, the environmental release continued to decrease, but at a slower rate after 2015. If subject to current policies, production and release would remain elevated with an expanding gap in between. This study also established the congener inventories, revealing the significance of OCDF and OCDD in terms of both production and release, and that of PeCDF and TCDF in terms of environmental impacts. Lastly, through comparison with other developed countries and regions, it was concluded that room for further reduction exists, but can only be achieved through strengthened regulations and improved control measures.

Implementing the Kigali Amendment to the Montreal Protocol has imposed certain restrictions on the production and consumption of hydrofluorocarbons (HFCs). Taking this opportunity to promote the alternatives of high global warming potential (GWP) HFC refrigerants in the room air conditioner (RAC) sector as well as improve the energy efficiency can bring double benefits. With the RAC sector as an example, a demand-emissions-cost model is developed to assess the potential and costs of emission reductions in different regions of China under different scenarios. The model includes three scenarios: a business as usual (BAU) scenario, a Kigali energy efficiency (KAE) scenario with simultaneous energy efficiency improvements following the Kigali amendment, and an accelerated transition energy efficiency (ATE) scenario with accelerated HFCs reduction and energy efficiency improvements. The results show that under the KAE and ATE scenario, the GHG emissions of the RAC sector will peak in 2025 at 389.8–393.9 Mt CO2-eq and 378.8–382.8 Mt CO2-eq in China. The main contribution to this result is the alternative of low GWP refrigerants. From 2021 to 2060, the cumulative direct emission reductions are about 6.4–7.4 Gt CO2-eq and 8.5–9.5 Gt CO2-eq in KAE and ATE, and the cumulative indirect emission re- ductions for both scenarios are 1.6–1.8 Gt CO2-eq. The cumulative abatement costs are $286–321 billion and $288–322 billion (prices in 2020). Under the ATE scenario, direct emissions from refrigerants in the RAC sector are near zero in 2060, and indirect emissions depend on the power system structure. The RAC sector’s average abatement cost varies significantly in diverse climatic environments. Given the variation in average abatement cost, it is critical to tailor mitigation policies to local conditions to ensure maximum benefits.

With the Kigali Amendment (KA) coming into effect in China, the control of hydrofluorocarbons (HFCs) emissions has become more imperative. The mobile air-conditioning (MAC) sector is one of the important HFCs consumer sectors, and therefore studying its feasible mitigation paths and costs is of great significance to China's successful implementation of KA. This study used the bottom-up method with updated emission factors to re-evaluate the emission inventory of HFCs from the MAC sector in China from 2005 to 2020. The average annual growth rate of HFCs consumption in the MAC sector is 9.8%, and HFCs emissions have increased from 5.8 (5.3‒6.2) kt in 2005 to 22.2 (20.6‒23.8) kt in 2020, with an average annual growth rate of 8.8%. Using the Gompertz model combined with the Weibull function of vehicle survival rate, the ownership and new registrations of internal combustion engine vehicles (ICEVs) and electric vehicles (EVs) in China are predicted. The ownership of ICEVs and EVs is projected to be 310 million and 91 million in 2030, respectively and 2 million and 641 million in 2060, respectively. HFCs emissions in the MAC sector would reach 59.8 (55.3‒64.3) kt (80.0‒93.0 Mt CO2- eq) in 2060 if without any control measure. To implement the KA, the cumulative of 1.6 Gt CO2-eq emissions would be reduced. Under the other two accelerated mitigation scenarios, the MAC sector's HFCs will reach their emissions peak in 2028 and 2025 and achieve zero emissions in 2050 and 2046, respectively. Under the accelerated mitigation with recovery scenario, the cumulative emissions are only 15.0% of the business as usual (BAU) scenario. Using HFO-1234yf as the substitute, the unit abatement cost of the MAC sector is 27.3‒37.4 USD t−1 CO2-eq.

With the successful implementation of the Montreal Protocol on Substances that Deplete the Ozone Layer, the atmospheric abundance of ozone-depleting substances continues to decrease slowly and the Antarctic ozone hole is showing signs of recovery. However, growing emissions of unregulated short-lived anthropogenic chlorocarbons are offsetting some of these gains. Here, we report an increase in emissions from China of the industrially produced chlorocarbon, dichloromethane (CH2Cl2). The emissions grew from 231 (213–245) Gg yr−1 in 2011 to 628 (599–658) Gg yr−1 in 2019, with an average annual increase of 13 (12–15) %, primarily from eastern China. The overall increase in CH2Cl2 emissions from China has the same magnitude as the global emission rise of 354 (281−427) Gg yr−1 over the same period. If global CH2Cl2 emissions remain at 2019 levels, they could lead to a delay in Antarctic ozone recovery of around 5 years compared to a scenario with no CH2Cl2 emissions.

Due to the characteristics of ozone-depleting and high global warming potential, chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs) have been restricted by the Montreal Pro- tocol and its amendments over the world. Considering that China is one of the main contributors to the emission of halocarbons, a long-term atmospheric observation on major substances including CFC-11 (CCl3F), CFC-12 (CCl2F2), HCFC-22 (CHClF2), HCFC-141b (CH3CCl2F), HCFC-142b (CH3CClF2) and HFC-134a (CH2FCF3) was conducted in five cities (Beijing, Hangzhou, Guangzhou, Lanzhou and Chengdu) of China during 2009–2019. The atmospheric concentrations of CFC-11, CFC-12, HCFC-141b and HCFC-142b all showed declining trends on the whole while those of HCFC-22 and HFC-134a were opposite. A paired sample t-test showed that the ambient mixing ratios of HCFC-22 and HFC-134a in cities were 41.9% and 25.7% higher on average than those in sub- urban areas, respectively, while the other substances did not show significant regional differences. The annual emissions of halocarbons were calculated using an interspecies correlation method and the results were generally consistent with the published estimates. Discrepancies between bottom-up inventories and the estimates in this study for CFCs emissions were found. Among the most consumed ozone depleting substances (ODSs) in China, CFCs accounted for 75.1% of the ozone depletion potential (ODP)-weighted emissions while HCFCs contributed a larger proportion (58.6%) of CO2-equivalent emissions in 2019. China’s emissions of HCFC-141b and HCFC-142b contributed the most to the global emission (17.8%–48.0%). The elimination of HCFCs in China will have a crucial impact on the HCFCs phase-out in the world.

The airborne occurrence, isomer profiles, and phase distribution of perfluoroalkyl acids (PFAAs), including perfluoroalkyl carboxylates (PFCAs) and sulfonates (PFSAs), have received little scientific attention to date. Here we collected gaseous and particulate phase (PM2.5) samples in China, between June and November 2013, using alkalized annular denuders and downstream filters toavoid sampling artefacts associated with traditional air sampling. We analysed the concentrations of 18 linear PFAAs and the branched isomers of perfluorooctanoate (PFOA) and perfluorooctane sulfonate (PFOS). Concentra- tions of total PFAAs were dominated by PFCAs, with a range of 6.6e610 pg/m3 in the gaseous phase and 2.3e290 pg/m3 in the particulate phase. Concentrations of total PFCAs were higher in summer than winter in both phases. Branched PFOA isomers accounted for 10e22% of total PFOA in the gaseous phase and 13e24% in the particulate phase, which is close to, but slightly lower than, their abundance in the commercial PFOA mixtures manufactured using the electrochemical fluorination (ECF) process. In con- tract, branched PFOS isomers accounted for 26-63% of total PFOS in the gaseous phase and 39-77% in the particulate phase, which is much higher than their abundance in commercial PFOS mixtures manufac- tured by ECF. Most PFCAs had mean particle-associated fractions (F) higher than 0.5. PFHxS had a much higher mean F (0.65) than linear PFOS (0.31). We hypothesise that PFAAs observed in Beijing air may originate from the local water bodies through processes such as aerosol generation, although trans- formation of precursors also contribute.

As the major producer and consumer of hydrofluorocarbons (HFCs), China is obligated to phase-down HFCs to mitigate global warming if China ratifies the Kigali Amendment (KA) to the Montreal Protocol. Based on historical HFCs consumption in each sector, here we estimated historical HFCs emissions with a bottom-up method, and projected the consumption baseline and schedule for HFCs phase-down in China under the KA and the corresponding potential for emission reduction. Results showed that China's HFCs consumption and emissions in 2017 were 164,000 t (311 Mt CO2-eq) and 108 Mt CO2-eq, respectively. HFCs consumption baseline was projected to be (724 ± 18) Mt CO2-eq in 2024, and China should take measures to phase-down HFCs by 2029, at the latest, to meet the requirements of the KA. HFCs consumption in 2050 under KA would reach the level of 2012–2013. Cumulative reduced consumption was estimated at 10.8 (10.1–11.6) Gt CO2-eq, and cumulative reduced emissions were estimated at 5.38 (4.90–5.64) Gt CO2-eq by 2050.

Abstract HFO-1234yf (2,3,3,3-tetrafluoropropene) was proposed as a mobile air conditioners (MACs) refrigerant worldwide. However, its atmospheric degradation product is the highly soluble and phytotoxic trifluoroacetic acid (TFA), which persists in aquatic environments. We used a global 3-D chemical transport model to assess the potential environmental effects resulting from complete future conversion of all MACs to HFO-1234yf in China, the United States and Europe. The annual mean atmospheric concentrations of HFO-1234yf were 2.62, 2.20 and 2.73 pptv, and the mean deposition rates of TFA were 0.96, 0.45 and 0.52 kg km-2 yr-1, in three regions. Regional TFA deposition sources mainly came from emissions within the same region. Annual TFA deposition in the North Pole region was lower than the global average and mainly originated from European emissions. A potential doubling in the future HFO-1234yf emissions in China mainly affected the local TFA depositions. The TFA concentrations in rainwater were strongly affected by the regional precipitation rates. North Africa and the Middle East, regions with scant rainfall had, extremely high TFA concentrations. The rainwater concentrations of TFA during individual rain events can exceed the level considered to be safe, indicating substantial potential regional risks from future HFO-1234yf use.

The ozone layer depletion and its recovery, as well as the climate influence of ozone-depleting substances (ODSs) and their substitutes that influence climate, are of interest to both the scientific community and the public. Here we report on the emissions of ODSs and their substitute from China, which is currently the largest consumer (and emitter) of these substances. We provide, for the first time, a comprehensive information on ODSs and replacement Hydrofluorocarbon (HFC) emissions in China starting from 1980 based on reported production and usage. We also assess the impacts (and costs) of controls on ODS consumption and emissions on the ozone layer (in terms of CFC-11-equivalent) and climate (in CO2-equivalent). In addition, we show that while China’s future ODS emissions are likely to be defined as long as there is full compliance with the Montreal Protocol, its HFC emissions through 2050 are very uncertain. Our findings imply that HFC controls over the next decades that are more stringent than those under the Kigali Amendment to the Montreal Protocol would be beneficial in mitigating global climate change.

Using coupled dynamic substance flow and environmental fate models, CiP-CAFE and BETR-Global, we investigated whether degradation of side-chain fluorotelomer-based polymers (FTPs), mostly in waste stocks (i.e., landfills and dumps), serves as a long-term source of fluorotelomer alcohols (FTOHs) and perfluoroalkyl carboxylates (PFCAs) to the global environment. The modelling results indicate that, in the wake of the worldwide transition from long-chain to short-chain products, in-use stocks of C8 FTPs will peak and decline afterwards while the in-use stocks of C6 FTPs and waste stocks of both FTPs will generally grow. FTP degradation in waste stocks is making an increasing contribution to FTOH generation, the bulk of which readily migrates from waste stocks and degrades into PFCAs in the environment; the remaining part of the generated FTOHs degrade in waste stocks, which makes those stocks reservoirs that slowly release PFCAs into the environment over the long run because of the low leaching rate and extr...