Eight decades of atmospheric abundances and emissions for three CFCs

The three minor chlorofluorocarbons CFC-13, CFC-114, and CFC-115 are not disappearing from the atmosphere as quickly as one would expect given their ban by the Montreal Protocol.

CFCs have been phased out under the Montreal Protocol for many years but there are still lingering emissions detectable. This has now been showed for the minor chlorofluorocarbons CFC-13, CFC-114, and CFC-115. Measurements of archived air collected in polar firn and in canisters are combined with the in-situ high-frequency measurements at the AGAGE stations. This has delivered global atmospheric records spanning eight decades, hence covering the entire histories of these CFCs in the atmosphere.

This is the first comprehensive study of CFC-13, a potent ozone-depletion gas with an atmospheric lifetime of more than 600 years. The compound has grown to more than 3 ppt in the global atmosphere and continued to grow at the same rate for at least the last 15 years, if not with accelerating growth. CFC-114 is declining in the global atmosphere, but not as fast as what would be expected with absent emissions. CFC-115 is growing in the global atmosphere at a rate that is even faster than that in the mid-2000s, but it remains unclear what the sources are.

We complemented this global analysis with a regional study to assess the emission strengths of these compounds from northeastern Asia. While the results for CFC-13 are inconclusive, it was shown that large fractions of the CFC-114 and CFC-115 emissions occur in northeastern Asia.

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Atmospheric histories and emissions of chlorofluorocarbons CFC-13 (CClF3), ΣCFC-114 (C2Cl2F4), and CFC-115 (C2ClF5). Vollmer, M.K., D. Young, C.M. Trudinger, J. Mühle, S. Henne, M. Rigby, S. Park, S. Li, M. Guillevic, B. Mitrevski, C.M. Harth, B.R. Miller, S. Reimann, B. Yao, L.P. Steele, S.A. Wyss, C.R. Lunder, J. Arduini, J., McCulloch, S. Wu, T.S. Rhee, R.H.J. Wang, P.K. Salameh, O. Hermansen, M. Hill, R.L. Langenfelds, D. Ivy, S. O'Doherty, P.B. Krummel, M. Maione, D.M. Etheridge, L. Zhou, P.J. Fraser, R.G. Prinn, R.F. Weiss and P.G. Simmonds (2018), Atmos. Chem. Phys., 18, 979-1002, doi:10.5194/acp-18-979-2018.