A renewed rise in global HCFC-141b emissions between 2017–2021
- 1Global Monitoring Laboratory, National Oceanic and Atmospheric Administration, Boulder, CO, USA
- 2School of Chemistry, University of Bristol, Bristol, UK
- 3Hadley Centre, Met Office, Exeter, UK
- 4Climate Science Centre, CSIRO Oceans and Atmosphere, Aspendale, Victoria, Australia
- 5Cooperative Institute for Research in Environmental Sciences, University of Colorado, University of Colorado, USA
- 6Empa, Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland
- 7College of Environmental and Resource Sciences, Zhejiang University, China
- 8A/gent b.v. Consultancy, Venlo, Netherlands
- 9Natural Resources Defense Council, USA
- 10Stratospheric Protection Division, Environmental Protection Agency, Washington, DC, USA
- 11Department of Pure and Applied Sciences, University of Urbino, Urbino, Italy
- 12Institute for Atmospheric and Environmental Science, Goethe University Frankfurt, Frankfurt am Main, Germany
- 13Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, USA
- 14Department of Oceanography, Kyungpook National University, Daegu, Republic of Korea
- 15Center for Global Change Science, Massachusetts Institute of Technology, Cambridge, MA, USA
- 1Global Monitoring Laboratory, National Oceanic and Atmospheric Administration, Boulder, CO, USA
- 2School of Chemistry, University of Bristol, Bristol, UK
- 3Hadley Centre, Met Office, Exeter, UK
- 4Climate Science Centre, CSIRO Oceans and Atmosphere, Aspendale, Victoria, Australia
- 5Cooperative Institute for Research in Environmental Sciences, University of Colorado, University of Colorado, USA
- 6Empa, Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland
- 7College of Environmental and Resource Sciences, Zhejiang University, China
- 8A/gent b.v. Consultancy, Venlo, Netherlands
- 9Natural Resources Defense Council, USA
- 10Stratospheric Protection Division, Environmental Protection Agency, Washington, DC, USA
- 11Department of Pure and Applied Sciences, University of Urbino, Urbino, Italy
- 12Institute for Atmospheric and Environmental Science, Goethe University Frankfurt, Frankfurt am Main, Germany
- 13Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, USA
- 14Department of Oceanography, Kyungpook National University, Daegu, Republic of Korea
- 15Center for Global Change Science, Massachusetts Institute of Technology, Cambridge, MA, USA
Abstract. Global emissions of the ozone depleting gas 1,1-dichloro-1-fluoroethane (HCFC-141b, CH3CCl2F), derived from measurements of atmospheric mole fractions, have been rising between 2017–2021 despite a fall in reported production and consumption for dispersive uses. This study evaluates the possible drivers behind this renewed rise in emissions. HCFC-141b is a controlled substance under the Montreal Protocol, and its phase-out is currently underway, after a peak in reported consumption and production in developing countries (Article 5) in 2013. If reported production and consumption are correct, it suggests that the 2017–2021 rise is due to an increase in emissions from the bank when HCFC-141b containing appliances reach the end of their life, or from production of HCFC-141b not reported for dispersive uses. Regional emissions have been estimated between 2017–2020 for all regions where measurements have sufficient sensitivity to emissions. This includes the regions of northwestern Europe, east Asia, the USA and Australia, where emissions decreased by a total of 1.6 ± 3.9 Gg yr−1, compared to a mean global increase of 3.0 ± 1.2 Gg yr−1 over the same period. Collectively these regions only account for around a third of global emissions in 2020. Therefore we are not able to pinpoint the source regions or specific activities responsible for the recent global emission rise.
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Luke M. Western et al.
Status: open (until 08 Jun 2022)
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RC1: 'Comment on acp-2022-298', Anonymous Referee #1, 19 May 2022
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The authors discuss the recent increase in emissions of HCFC-141b derived from observed atmospheric mole fractions by two measurement networks. They discuss reasons of this increase, but can not find a clear source. Several potential sources are discussed and mostly excluded. The paper is well written and scientifically sounds. Well founded measurements and inversion methods are presented and discussed with a solid uncertainty analyses.
Specifics comments:
L11: The word “Therefore” does not following logically from the previous sentences. I suggest to rephrase the sentence or simply omit the word.
L74: Remove the first occurrence of “not” in the sentence.
L140-144: Emission release fractions are determined using a statistical approach. Can you explain how you distinguish between A5 and nonA5 countries? It says “as these measurements predate the non-negligible global consumption”. Does that mean that release fractions for nonA5 are determined mostly from the period 1990-2000 and for A5 after about 2010? Also, you assume that the release fractions are constant in time. This seems valid for the ‘regular’ use of HCFC-141b, but what if there is illegal production, use, or disposal? Please discuss this, maybe around lines L312-313..
L286-287: The hemispheric differences increases from 2018 to 2021. The low hemispheric difference is only seen for 2018, a single year (what I deduce from Fig 3). With a decrease in use and emissions you would expect the hemispheric difference to become smaller, but since it is now only seen in one year, I doubt it is a valid/strong argument. Please say something about this.
P12: Caption Fig 4: From the caption it now seems that the left panel shows the consumption data and not emissions estimated from consumption data. I think you can solve this by writing “…, and from reported consumption data …”.
L330: The disposal could on average be 15 years after peak in consumption, but it will be a rather broad peak, I assume. I would mention this, since it may be a reason why an increase in HCFC-141b emissions started in 2018 (and not in 2026).
L338-340: I would rephrase this sentence. Something like, “A universal leakage rate of 20% in 2020, compared to 0.1% in 2017 would be needed to explain the observed global increase .in emissions …”.
L352-354 and L357-359: The emissions from eastern China, scaled down from the whole of China, from Fang et al. (2018) show an increase (Fig 5), but the emissions from the whole of China from Fang et al. (2019) show a decrease? This seems inconsistent? Is there separate information for the rest of China that shows an increase?
L357: Please give a reference for the “Act on Rational use …”.
L416-418: I suggest you mention here that the increase in Chinese CFC-11 emissions could only explain 40-60% of the global increase. This would support the idea that the extra emissions in part originate from regions not monitored. This connect to the statement in L440-442.
Luke M. Western et al.
Luke M. Western et al.
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