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Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
© Author(s) 2017. This work is distributed under
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Research article
12 Oct 2017
Review status
This discussion paper is a preprint. A revision of this manuscript was accepted for the journal Atmospheric Chemistry and Physics (ACP) and is expected to appear here in due course.
Recent increases in the atmospheric growth rate and emissions of HFC-23 (CHF3) and the link to HCFC-22 (CHClF2) production
Peter G. Simmonds1, Matthew Rigby1, Archie McCulloch1, Martin K. Vollmer2, Stephan Henne2, Jens Mühle3, Simon O'Doherty1, Alistair J. Manning4, Paul B. Krummel5, Paul J. Fraser5, Dickon Young1, Ray F. Weiss3, Peter K. Salameh3, Chris M. Harth3, Stephan Reimann2, Cathy M. Trudinger5, Paul Steele5, Ray H. J. Wang6, Diane J. Ivy7, Ron G. Prinn7, Blagoj Mitrevski5, and David M. Etheridge5 1Atmospheric Chemistry Research Group, University of Bristol, Bristol, UK
2Empa, Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Air Pollution and Environmental Technology, Dübendorf, Switzerland
3Scripps Institution of Oceanography (SIO), University of California, San Diego, La Jolla, California, USA
4Met Office Hadley Centre, Exeter, UK
5Climate Science Centre, CSIRO Oceans and Atmosphere, Aspendale, Victoria, Australia
6School of Earth, and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA
7Center for Global Change Science, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
Abstract. High frequency measurements of the potent hydrofluorocarbon greenhouse gas CHF3 (HFC-23), a by-product of production of the hydrochlorofluorocarbon HCFC-22 (CHClF2), at five core stations of the Advanced Global Atmospheric Gases Experiment (AGAGE) network, combined with measurements of firn and Cape Grim Air Archive (CGAA) air samples, are used to explore the changing atmospheric abundance of HFC-23. These measurements are used in combination with the AGAGE 2-D atmospheric 12-box model and a Bayesian inversion methodology to determine model atmospheric mole fractions and the atmospheric history of global HFC-23 emissions. The global modelled annual mole fraction of HFC-23 in the background atmosphere was 28.9 ± 0.6 pmol mol−1 at the end of 2016, representing a 28 % increase from 22.6 ± 0.4 pmol mol−1 in 2009. Over the same time frame, the modelled mole fraction of HCFC-22 increased by 19 % from 199 ± 2 pmol mol−1 to 237 ± 2 pmol mol−1. However, the annual average HCFC-22 growth rate decelerated from 2009 to 2016 at an annual average rate of 0.5 pmol mol−1 yr−2.

Our results demonstrate that, following a minimum in HFC-23 global emissions in 2009 of 9.6 ± 0.6 Gg yr−1, emissions increased to a maximum in 2014 of 14.5 ± 0.6 Gg yr−1, declining to 12.7 ± 0.6 Gg yr−1 (157 Mt  CO2-eq. yr−1) in 2016. The 2009 emissions minimum is consistent with estimates based on national reports and is likely a response to the implementation of the Clean Development Mechanism (CDM) to mitigate HFC-23 emissions by incineration in developing (Non-Annex 1) countries under the Kyoto Protocol. Our derived cumulative emissions of HFC-23 during 2010–2016 were 89 ± 2 Gg (1.1 ± 0.2 Gt CO2-eq), which led to an increase in radiative forcing of 1.0 ± 0.1 mW m−2. Although the CDM had reduced global HFC-23 emissions, it cannot now offset the radiative forcing of higher emissions from increasing HCFC-22 production in Non-Annex 1 countries, as the CDM was closed to new entrants in 2009. We also find that the cumulative European HFC-23 emissions from 2010 to 2016 were ~ 1.3 Gg, corresponding to just 1.5 % of cumulative global HFC-23 emissions over this same period.

Citation: Simmonds, P. G., Rigby, M., McCulloch, A., Vollmer, M. K., Henne, S., Mühle, J., O'Doherty, S., Manning, A. J., Krummel, P. B., Fraser, P. J., Young, D., Weiss, R. F., Salameh, P. K., Harth, C. M., Reimann, S., Trudinger, C. M., Steele, P., Wang, R. H. J., Ivy, D. J., Prinn, R. G., Mitrevski, B., and Etheridge, D. M.: Recent increases in the atmospheric growth rate and emissions of HFC-23 (CHF3) and the link to HCFC-22 (CHClF2) production, Atmos. Chem. Phys. Discuss.,, in review, 2017.
Peter G. Simmonds et al.
Peter G. Simmonds et al.


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Short summary
Recent measurements of the potent greenhouse gas HFC-23, a by-product of HCFC-22 production show a 28 % increase in the atmospheric mole fraction from 2009–2016. A minimum in the atmospheric abundance of HFC-23 in 2009 was attributed to abatement of HFC-23 emissions by incineration under the Clean Development Mechanism (CDM). Our results indicate that the recent increase in HFC-23 emissions is driven by a failure of mitigation under the CDM to keep pace with the increase in HCFC-22 production.
Recent measurements of the potent greenhouse gas HFC-23, a by-product of HCFC-22 production show...