Changes in Emissions of Ozone-Depleting Substances from China Due to Implementation of the Montreal Protocol.

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, 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.

Historical emissions of HFC-23 (CHF3) in China and projections upon policy options by 2050.

Trifluoromethane (CHF3, HFC-23) is one of the hydrofluorocarbons (HFCs) regulated under the Kyoto Protocol with a global warming potential (GWP) of 14 800 (100-year). China's past, present, and future HFC-23 emissions are of considerable interest to researchers and policymakers involved in climate change. In this study, we compiled a comprehensive historical inventory (1980-2012) and a projection (2013-2050) of HFC-23 production, abatements, and emissions in China. Results show that HFC-23 production in China increased from 0.08 ± 0.05 Gg/yr in 1980 to 15.4 ± 2.1 Gg/yr (228 ± 31 Tg/yr CO2-eq) in 2012, while actual HFC-23 emissions reached a peak of 10.5 ± 1.8 Gg/yr (155 ± 27 Tg/y CO2-eq) in 2006, and decreased to a minimum of 7.3 ± 1.3 Gg/yr (108 ± 19 Tg/yr CO2-eq) in 2008 and 2009. Under the examined business-as-usual (BAU) scenario, the cumulative emissions of HFC-23 in China over the period 2013-2050 are projected to be 609 Gg (9015 Tg CO2-eq which approximates China's 2012 CO2 emissions). Currently, China's annual HFC-23 emissions are much higher than those from the developed countries, while it is estimated that by year 2027, China's historic contribution to the global atmospheric burden of HFC-23 will have surpassed that of the developed nations under the BAU scenario.

Sulfur hexafluoride (SF6) emission estimates for China: an inventory for 1990-2010 and a projection to 2020.

Sulfur hexafluoride (SF6) is the most potent greenhouse gas regulated under the Kyoto Protocol, with a high global warming potential. In this study, SF6 emissions from China were inventoried for 1990-2010 and projected to 2020. Results reveal that the highest SF6 emission contribution originates from the electrical equipment sector (about 70%), followed by the magnesium production sector, the semiconductor manufacture sector and the SF6 production sector (each about 10%). Both agreements and discrepancies were found in comparisons of our estimates with previously published data. An accelerated growth rate was found for Chinese SF6 emissions during 1990-2010. Because the relative growth rate of SF6 emissions is estimated to be much higher than those of CO2, CH4, and N2O, SF6 will play an increasing role in greenhouse gas emissions in China. Global contributions from China increased rapidly from 0.9 ± 0.3% in 1990 to 22.8 ± 6.3% in 2008, making China one of the crucial contributors to the recent growth in global emissions. Under the examined Business-as-usual (BAU) Scenario, projected emissions will reach 4270 ± 1020 t in 2020, but a reduction of about 90% of the projected BAU emissions would be obtained under the Alternative Scenario.

Sulfur dioxide emissions from combustion in china: from 1990 to 2007.

China has become the world's largest emitter of SO(2) since 2005, and aggressive deployment of flue gas desulfurization (FGD) at coal-fired power plants appeared in China when facing the formidable pressure of environment pollution. In this work, we estimate the annual emission from combustion sources at provincial levels in China from 1990 to 2007, with updated data investigations. We have implemented the method of transportation matrix to gain a better understanding of sulfur content of coal in consuming provinces, which in turn improved the inventory. The total emissions from combustion in 2007 were 28.3 Tg, half of which was contributed by coal-fired power plants. Meanwhile, the industrial boiler coal combustion and residential coal consumed in centralized heating were responsible for another 32% of the total emissions. From 1990 to 2007, annual SO(2) emission was fluctuated with two peaks (1996 and 2006), and total emission doubled from 15.4 Tg to 30.8 Tg, at an annual growth rate of 4.4% (6.3% since 2000). Due to the extensive application of FGD technology and the phase-out of small, high emitting units, the SO(2) emission began to decrease after 2006. Furthermore, the differences among estimates reported in literatures highlight a great need for further research to reduce the uncertainties with more detailed information on key sources and actual operation of devices.

Global time trends in PAH emissions from motor vehicles.

Emission from motor vehicles is the most important source of polycyclic aromatic hydrocarbons (PAHs) in urban areas. Emission factors of individual PAHs for motor vehicles reported in the literature varied 4 to 5 orders of magnitude, leading to high uncertainty in emission inventory. In this study, key factors affecting emission factors of PAHs (EFPAH) for motor vehicles were evaluated quantitatively based on thousands of EFPAH measured in 16 countries for over 50 years. The result was used to develop a global emission inventory of PAHs from motor vehicles. It was found that country and vehicle model year are the most important factors affecting EFPAH, which can be quantified using a monovariate regression model with per capita gross domestic production (purchasing power parity) as a sole independent variable. On average, 29% of variation in log-transformed EFPAH could be explained by the model, which was equivalent to 90% reduction in overall uncertainty on arithmetic scale. The model was used to predict EFPAH and subsequently PAH emissions from motor vehicles for various countries in the world during a period from 1971 to 2030. It was estimated that the global emission reached its peak value of approximate 101 Gg in 1978 and decreased afterwards due to emission control in developed countries. The annual emission picked up again since 1990 owing to accelerated energy consumption in China and other developing countries. With more and more rigid control measures taken in the developing world, global emission of PAHs is currently passing its second peak. It was predicted that the emission would decrease from 77 Gg in 2010 to 42 Gg in 2030.

Estimated emissions of chlorofluorocarbons, hydrochlorofluorocarbons, and hydrofluorocarbons based on an interspecies correlation method in the Pearl River Delta region, China.

Although many studies have been conducted in recent years on the emissions of chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), and hydrofluorocarbons (HFCs) at the large regional (such as East Asia) and national scales, relatively few studies have been conducted for cities or metropolitan areas. In this study, 192 air samples were collected in the Pearl River Delta (PRD) region of China in November 2010. The atmospheric mixing ratios of six halocarbons were analyzed, including trichlorofluoromethane (CFC-11, CCl3F), dichlorodifluoromethane (CFC-12, CCl2F2), monochlorodifluoromethane (HCFC-22, CHClF2), 1,1-dichloro-1-fluoroethane (HCFC-141b, CH3CCl2F), 1-dichloro-1,1-fluoroethane (HCFC-142b, CH3CClF2), and 1,1,1,2-tetrafluoroethane (HFC-134a, CH2FCF3), and their emissions were estimated based on an interspecies correlation method using HCFC-22 as the reference species. The results showed no significant change in the regional concentration and emission of CFC in the past 10years, suggesting that the continuous regional emission of CFC has had no significant effect on the CFC regional concentration in the PRD region. Concentrations and emissions of HCFCs and HFCs are significantly higher compared to previous research in the PRD region (P<0.05). The largest emission was for HCFC-22, most likely due to its substitution for CFC-12 in the industrial and commercial refrigeration subsector, and the rapid development of the room air-conditioner and extruded polystyrene subsectors. The PRD's ODP-weighted emissions of the target HCFCs provided 9% (7-12%) of the national emissions for the corresponding species. The PRD's GWP-weighted emissions of the target HCFCs and HFC-134a account for 10% (7-12%) and 8% (7-9%), respectively, of the national emissions for the corresponding species, and thus are important contributions to China's total emissions.