Airborne Observations of CFCs Over Hebei Province, China in Spring 2016

Benish, Sarah E.; Salawitch, R. J.; Ren, Xinrong; He, Hao; Dickerson, Russell R.

doi:10.1029/2021jd035152

Cited by 8 publications

(3 citation statements)

References 77 publications

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“…This was the case with unexpected emissions of CFC-11 after 2012 (Benish et al, 2021;Lickley et al, 2020;Park et al, 2018;Rigby et al, 2019), where allowing for production uncertainty in the banks modeling framework over this time period resulted in posterior production estimates that were non-zero following 2010, and larger posterior bank values than what was inferred by assuming zero production uncertainty and full compliance with the Protocol following 2010.…”

Section: Resultsmentioning

confidence: 99%

“…For the 2022 SAOD report, new production of controlled substances not in compliance with the Montreal Protocol was considered; this new production is included implicitly through increases to both atmospheric concentrations and explicitly through the bank size of the affected ODS. These updates have been made in light of evidence of unreported production of halocarbons in recent years (Benish et al, 2021;Lickley et al, 2022;Park et al, 2018;Rigby et al, 2019;Montzka et al, 2021;Park et al, 2021;Sherry et al, 2018) as well as during the 1980s in the Soviet Union at an amount that accounted for ~20% of global production of CFC-11 (Gamlen et al, 1986), suggesting historical production may have been consistently underestimated in earlier SAOD reports. Production of CCl4 has similarly been consistently underestimated in the SAODs (SPARC, 2016).…”

Section: Resultsmentioning

confidence: 99%

“…We henceforth refer to these five reports as the 2006; 2010; 2014; 2018; and 2022 SAODs. Specifically, we consider how the delay has been affected by the consistent underestimate of the global production of ODSs (Benish et al, 2021;Lickley et al, 2022;Park et al, 2018;Rigby et al, 2019;Montzka et al, 2021;Park et al, 2021;Sherry et al, 2018), as modeled through banks and feedstocks, and observed in part by measured mole fractions following each SAODs publication. In addition, we consider the role of changes in ODS atmospheric lifetime assumptions that affect future atmospheric abundances (SPARC, 2013), and variations in the scientific understanding of the best underlying approach used to compute EESC (Engel et al, 2018;Newman et al, 2007).…”

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confidence: 99%

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The return to 1980 stratospheric halogen levels: A moving target in ozone assessments from 2006 to 2022

Lickley,

Daniel,

McBride

et al. 2024

Preprint

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Abstract. The international scientific assessment of ozone depletion is prepared every four years to support decisions made by the Parties to the Montreal Protocol. In each assessment an outlook of ozone recovery time is provided. The year when equivalent effective stratospheric chlorine (EESC) returns to the level found in 1980 is an important metric for the recovery of the ozone layer. Over the past five assessments, the expected date for the return of EESC to the 1980 level, for mid-latitudes, has been delayed, from year 2049 in the 2006 assessment to 2066 in the 2022 assessment, which represents a delay of 17 years over a 16-year assessment period. Here, we quantify the primary drivers that have delayed the expected EESC recovery date between each of these assessments. We find that by using identical EESC formulations the delay between the 2006 and 2022 assessment’s expected return of EESC to 1980 levels is shortened to 12.6 years. Of this delay, bank calculation methods account for ~4 years, changes in the assumed atmospheric lifetime for certain ODSs account for ~3.5 years, an under-estimate of the emission of CCl4 accounts for ~3 years, and updated historical mole fraction estimates of ODSs account for ~1 year. Since some of the underlying causes of these delays are amenable to future controls (e.g. capture of ODSs from banks and limitations on future feedstock emissions), it is important to understand the reasons for the delays in expected recovery date of stratospheric halogens.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

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The return to 1980 stratospheric halogen levels: A moving target in ozone assessments from 2006 to 2022

Lickley,

Daniel,

McBride

et al. 2024

Preprint

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CCl4 emissions in eastern China during 2021–2022 and exploration of potential new sources

Li,

Huang,

et al. 2024

Nat Commun

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According to the Montreal Protocol, the production and consumption of ozone-layer-depleting CCl4 for dispersive applications was globally phased out by 2010, including China. However, continued CCl4 emissions were disclosed, with the latest CCl4 emissions unknown in eastern China. In the current study, based on the atmospheric measurements of ~12,000 air samples taken at two sites in eastern China, the 2021–2022 CCl4 emissions are quantified as 7.6 ± 1.7 gigagrams per year. This finding indicates that CCl4 emissions continued after being phased out for dispersive uses in 2010. Subsequently, our study identifies potential industrial sources (manufacture of general purpose machinery and manufacture of raw chemical materials, and chemical products) of CCl4 emissions.

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CFC-11 measurements in China, Nepal, Pakistan, Saudi Arabia and South Korea (1998–2018): Urban, landfill fire and garbage burning sources

et al. 2022

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Environmental context The production and consumption of chlorofluorocarbons (CFCs) is regulated under the Montreal Protocol and its amendments, due to their role in stratospheric ozone depletion. Global atmospheric levels of CFC-11 did not decline as rapidly as expected during 2012–2018, in large part due to emissions from eastern China. In order to further clarify global CFC-11 emissions, this work provides a rare set CFC-11 measurements from understudied countries and sources throughout Asia (1998–2018). Abstract Trichlorofluoromethane (CFC-11) is an ozone-depleting substance whose production and consumption are regulated under the Montreal Protocol. Global atmospheric CFC-11 levels declined less quickly than expected during 2012–2018, largely because of ongoing emissions from eastern Asia. Satellite measurements suggest additional CFC-11 hotspots in the Arabian Peninsula and north India/Nepal. Here we present CFC-11 levels measured in dozens of Asian cities during 1998–2018, including China and Pakistan before the 2010 phaseout of CFC-11, and China, Nepal, Pakistan, Saudi Arabia and South Korea after the phaseout. Surface measurements of CFCs in Nepal, Pakistan and Saudi Arabia are very rare, and these surveys provide important observational constraints from understudied regions. During pre-phaseout campaigns, higher CFC-11 levels were measured in Beijing than Karachi, despite much higher overall volatile organic compound (VOC) levels in Karachi. During post-phaseout campaigns, average CFC-11 levels were higher in inland Shandong Province and Seoul (1.11–1.23× background) than in western Saudi Arabia, Lahore and Kathmandu (1.02–1.11× background), despite higher levels of other VOCs in the latter regions. While China is known to emit excess CFC-11, elevated CFC-11 levels in Seoul, especially during stagnant meteorological conditions, suggest local emissions in 2015–2016. Rough emission estimates suggest that South Korea is likely a relatively minor global source of excess CFC-11. Hotspot CFC-11 levels were measured from a landfill fire in Mecca (average of 1.8× background) and from garbage burning in Nepal (1.5× background). Because garbage burning and open burning in dumps are common practices, further investigation of CFC-11 emissions at dumps and landfills worldwide is encouraged to determine their global impact.

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Airborne Observations of CFCs Over Hebei Province, China in Spring 2016

Cited by 8 publications

References 77 publications

The return to 1980 stratospheric halogen levels: A moving target in ozone assessments from 2006 to 2022

The return to 1980 stratospheric halogen levels: A moving target in ozone assessments from 2006 to 2022

CCl4 emissions in eastern China during 2021–2022 and exploration of potential new sources

CFC-11 measurements in China, Nepal, Pakistan, Saudi Arabia and South Korea (1998–2018): Urban, landfill fire and garbage burning sources

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