Abstract
The Los Angeles (LA) basin was responsible for approximately 20% of California’s methane emissions in 2016. Hence, curtailment of these emissions is required to meet California’s greenhouse ...gas emissions reduction targets. However, effective mitigation remains challenging in the presence of diverse methane sources like oil and gas production fields, refineries, landfills, wastewater treatment facilities, and natural gas infrastructure. In this study, we study the temporal variability in the surface concentrations from February 2015 to April 2022 to detect a declining trend in methane emissions. We quantify the reduction due to this declining trend through inverse modeling and show that methane emissions in the LA basin have declined by 15 Gg, or ∼7% over five years from January 2015 to May 2020.
High‐frequency in‐situ measurements of a wide range of halogenated compounds including chlorofluorocarbons (CFCs), halons, hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons (HFCs), perfluorinated ...compounds (PFCs), sulfur hexafluoride (SF6), and other chlorinated and brominated compounds have been made at Gosan (Jeju Island, Korea). Regional emissions of HCFC‐22 (CHClF2) calculated from inverse modeling were combined with interspecies correlation methods to estimate national emissions for China, a major emitter of industrial halogenated gases. Our results confirm the signs of successful phase‐out of primary ozone‐depleting species such as CFCs, halons and many chlorinated or brominated compounds, along with substantial emissions of replacement HCFCs. Emissions derived for HFCs, PFCs, and SF6 were compared to published estimates and found to be a significant fraction of global totals. Overall, Chinese emissions of the halogenated compounds discussed here represent 19(14–17)% and 20(15–26)% of global emissions when evaluated in terms of their Ozone Depletion Potentials and 100‐year Global Warming Potentials, respectively.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The sources of halogenated compounds in East Asia associated with stratospheric ozone depletion and climate change are relatively poorly understood. High-precision in situ measurements of 18 ...halogenated compounds and carbonyl sulfide (COS) made at Gosan, Jeju Island, Korea, from November 2007 to December 2011 were analyzed by a positive matrix factorization (PMF). Seven major industrial sources were identified from the enhanced concentrations of halogenated compounds observed at Gosan and corresponding concentration-based source contributions were also suggested: primary aluminum production explaining 37% of total concentration enhancements, solvent usage of which source apportionment is 25%, fugitive emissions from HCFC/HFC production with 11%, refrigerant replacements (9%), semiconductor/electronics industry (9%), foam blowing agents (6%), and fumigation (3%). Statistical trajectory analysis was applied to specify the potential emission regions for seven sources using back trajectories. Primary aluminum production, solvent usage and fugitive emission sources were mainly contributed by China. Semiconductor/electronics sources were dominantly located in Korea. Refrigerant replacement, fumigation and foam blowing agent sources were spread throughout East Asian countries. The specified potential source regions are consistent with country-based consumptions and emission patterns, verifying the PMF analysis results. The industry-based emission sources of halogenated compounds identified in this study help improve our understanding of the East Asian countries’ industrial contributions to halogenated compound emissions.
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IJS, KILJ, NUK, PNG, UL, UM
Nitrogen trifluoride (NF ₃) has potential to make a growing contribution to the Earth’s radiative budget; however, our understanding of its atmospheric burden and emission rates has been limited. ...Based on a revision of our previous calibration and using an expanded set of atmospheric measurements together with an atmospheric model and inverse method, we estimate that the global emissions of NF ₃ in 2011 were 1.18 ± 0.21 Gg⋅y ⁻¹, or ∼20 Tg CO ₂-eq⋅y ⁻¹ (carbon dioxide equivalent emissions based on a 100-y global warming potential of 16,600 for NF ₃). The 2011 global mean tropospheric dry air mole fraction was 0.86 ± 0.04 parts per trillion, resulting from an average emissions growth rate of 0.09 Gg⋅y ⁻² over the prior decade. In terms of CO ₂ equivalents, current NF ₃ emissions represent between 17% and 36% of the emissions of other long-lived fluorinated compounds from electronics manufacture. We also estimate that the emissions benefit of using NF ₃ over hexafluoroethane (C ₂F ₆) in electronics manufacture is significant—emissions of between 53 and 220 Tg CO ₂-eq⋅y ⁻¹ were avoided during 2011. Despite these savings, total NF ₃ emissions, currently ∼10% of production, are still significantly larger than expected assuming global implementation of ideal industrial practices. As such, there is a continuing need for improvements in NF ₃ emissions reduction strategies to keep pace with its increasing use and to slow its rising contribution to anthropogenic climate forcing.
Abstract
Urban regions emit a large fraction of anthropogenic emissions of greenhouse gases (GHG) such as carbon dioxide (CO
2
) and methane (CH
4
) that contribute to modern-day climate change. As ...such, a growing number of urban policymakers and stakeholders are adopting emission reduction targets and implementing policies to reach those targets. Over the past two decades research teams have established urban GHG monitoring networks to determine how much, where, and why a particular city emits GHGs, and to track changes in emissions over time. Coordination among these efforts has been limited, restricting the scope of analyses and insights. Here we present a harmonized data set synthesizing urban GHG observations from cities with monitoring networks across North America that will facilitate cross-city analyses and address scientific questions that are difficult to address in isolation.
High-precision (±0.1 ppm) and high-frequency (hourly averaged) in situ measurements of atmospheric carbon dioxide (CO2) were made for the first time from August 2005 to July 2007 at Yanbian, China ...using a non-dispersive Infrared (NDIR) analyz- er with National Oceanic and Atmospheric Administration/Earth System Research Laboratory (NOAA/ESRL) standards. The results of these measurements are presented in this paper and are used to investigate the regional representativeness of regional background data at Yanbian and determine the CO2 emission source regions in Northeast Asia. The phase of the monthly vari- ations at Yanbian reflects the special regional characteristics, which were overall in excellent agreement with other observato- ries in the middle-to-high latitudes in the Northern Hemisphere. Applying a hybrid receptor model to the regional emission source events in cold period (November-April), we estimated the distribution of the major CO2 emissions in the northeast Asia. The results indicated that the strongest potential emission areas contributing to Yanbian are the Beijing & Tianjin metropolitan areas, southwestern part of Shandong Province including Jinan, and Vladivostok. The results of this study reveal the usefulness of in situ CO2 measurements at Yanbian in establishing the scientific foundation for monitoring the large CO2 emission areas in northern China and Russia. Continued monitoring of CO2 at Yanbian within a regional network should provide significant contributions to both understanding the global/regional carbon cycle and constraining "top-down" emissions in Northeast Asia.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
High-Precision (±0.1 ppm), high-frequency (hourly averaged) measurement of atmospheric carbon dioxide (CO2) was made at Gosan Station on Jeju Island, Korea, using a Non-dispersive Infrared (NDIR) ...analyzer calibrated with National Oceanic and Atmospheric Administration/Earth Sys tem Re search Laboratory standards. This paper presents the one-year results from these measurements, including discussions on data quality control and data selection, data characteristics through comparing with other regional data and on the techniques for estimating potential source regions of pollution emissions in Northeast Asia with pollution events in the record. Comparisons of the continuous monitoring data with in dependent flask measurements at Gosan show good correlation in overall trend. In addition, the continuous monitoring data show signals of extreme pollution and sink episodes which are difficult to monitor indiscrete flask measurements, showing the importance of continuous measurements. The CO2 concentrations of "representative data" at Gosan, derived by the statistical pollution identification procedure, show strong seasonality similar to those of other background observaories in the middle-to-high Northern Hemisphere. The amplitude of the seasonal variation at Gosan is approximately 16 ppm, similar to high-latitude Northern Hemi sphere marine sites such as Ryori and Point Barrow stations. A hybrid receptor model was applied to the "regional pollution events", a statistically extracted subset of the data with a high probability of being influenced by regional pollution for under standing the distribution and strengths of the major CO2 pollution sources in the Northeast Asia region. Results indicate strong potential source areas around the Yangtze River region including Shanghai and the Huabei plain including Beijing of China, as well as the Korean peninsula including Seoul contributing to pollution events observed at Gosan. The methodologies and results describe our continuing efforts in establishing a "top-down" estimation of greenhouse gas emissions in the Northeast Asia region, important for scientific validation and monitoring of anthropogenic CO2 emissions from the active industrial development in this region.
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FFLJ, IZUM, KILJ, NUK, ODKLJ, PILJ, PNG, SAZU, UL, UM, UPUK
The perfluorocarbons tetrafluoromethane (CF 4 , PFC-14) and hexafluoroethane (C 2 F 6 , PFC-116) are potent greenhouse gases with near-permanent atmospheric lifetimes relative to human timescales and ...global warming potentials thousands of times that of CO 2 . Using long-term atmospheric observations from a Chinese network and an inverse modeling approach (top–down method), we determined that CF 4 emissions in China increased from 4.7 (4.2-5.0, 68% uncertainty interval) Gg y −1 in 2012 to 8.3 (7.7-8.9) Gg y −1 in 2021, and C 2 F 6 emissions in China increased from 0.74 (0.66-0.80) Gg y −1 in 2011 to 1.32 (1.24-1.40) Gg y −1 in 2021, both increasing by approximately 78%. Combined emissions of CF 4 and C 2 F 6 in China reached 78 Mt CO 2 -eq in 2021. The absolute increase in emissions of each substance in China between 2011-2012 and 2017-2020 was similar to (for CF 4 ), or greater than (for C 2 F 6 ), the respective absolute increase in global emissions over the same period. Substantial CF 4 and C 2 F 6 emissions were identified in the less-populated western regions of China, probably due to emissions from the expanding aluminum industry in these resource-intensive regions. It is likely that the aluminum industry dominates CF 4 emissions in China, while the aluminum and semiconductor industries both contribute to C 2 F 6 emissions. Based on atmospheric observations, this study validates the emission magnitudes reported in national bottom–up inventories and provides insights into detailed spatial distributions and emission sources beyond what is reported in national bottom–up inventories.
Emissions of ozone-depleting substances, including trichlorofluoromethane (CFC-11), have decreased since the mid-1980s in response to the Montreal Protocol
. In recent years, an unexpected increase ...in CFC-11 emissions beginning in 2013 has been reported, with much of the global rise attributed to emissions from eastern China
. Here we use high-frequency atmospheric mole fraction observations from Gosan, South Korea and Hateruma, Japan, together with atmospheric chemical transport-model simulations, to investigate regional CFC-11 emissions from eastern China. We find that CFC-11 emissions returned to pre-2013 levels in 2019 (5.0 ± 1.0 gigagrams per year in 2019, compared to 7.2 ± 1.5 gigagrams per year for 2008-2012, ±1 standard deviation), decreasing by 10 ± 3 gigagrams per year since 2014-2017. Furthermore, we find that in this region, carbon tetrachloride (CCl
) and dichlorodifluoromethane (CFC-12) emissions-potentially associated with CFC-11 production-were higher than expected after 2013 and then declined one to two years before the CFC-11 emissions reduction. This suggests that CFC-11 production occurred in eastern China after the mandated global phase-out, and that there was a subsequent decline in production during 2017-2018. We estimate that the amount of the CFC-11 bank (the amount of CFC-11 produced, but not yet emitted) in eastern China is up to 112 gigagrams larger in 2019 compared to pre-2013 levels, probably as a result of recent production. Nevertheless, it seems that any substantial delay in ozone-layer recovery has been avoided, perhaps owing to timely reporting
and subsequent action by industry and government in China
.
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GEOZS, IJS, IMTLJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK, ZAGLJ
The perfluorocarbons tetrafluoromethane (CF4, PFC-14) and hexafluoroethane (C2F6, PFC-116) are potent greenhouse gases with near-permanent atmospheric lifetimes relative to human timescales and ...global warming potentials thousands of times that of CO2. Using long-term atmospheric observations from a Chinese network and an inverse modeling approach (top–down method), we determined that CF4 emissions in China increased from 4.7 (4.2-5.0, 68% uncertainty interval) Gg y−1 in 2012 to 8.3 (7.7-8.9) Gg y−1 in 2021, and C2F6 emissions in China increased from 0.74 (0.66-0.80) Gg y−1 in 2011 to 1.32 (1.24-1.40) Gg y−1 in 2021, both increasing by approximately 78%. Combined emissions of CF4 and C2F6 in China reached 78 Mt CO2-eq in 2021. The absolute increase in emissions of each substance in China between 2011-2012 and 2017-2020 was similar to (for CF4), or greater than (for C2F6), the respective absolute increase in global emissions over the same period. Substantial CF4 and C2F6 emissions were identified in the less-populated western regions of China, probably due to emissions from the expanding aluminum industry in these resource-intensive regions. It is likely that the aluminum industry dominates CF4 emissions in China, while the aluminum and semiconductor industries both contribute to C2F6 emissions. Based on atmospheric observations, this study validates the emission magnitudes reported in national bottom–up inventories and provides insights into detailed spatial distributions and emission sources beyond what is reported in national bottom–up inventories.