On the effects of the ocean on atmospheric CFC-11 lifetimes and emissions

Wang, Peidong, Scott, Jeffery R., Solomon, Susan, Marshall, John, Babbin, Andrew R., Lickley, Megan, Thompson, David W. J. ORCID: https://orcid.org/0000-0002-5413-4376, DeVries, Timothy, Liang, Qing and Prinn, Ronald G. (2021) On the effects of the ocean on atmospheric CFC-11 lifetimes and emissions. Proceedings of the National Academy of Sciences, 118 (12). ISSN 0027-8424

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The ocean is a reservoir for CFC-11, a major ozone-depleting chemical. Anthropogenic production of CFC-11 dramatically decreased in the 1990s under the Montreal Protocol, which stipulated a global phase out of production by 2010. However, studies raise questions about current overall emission levels and indicate unexpected increases of CFC-11 emissions of about 10 Gg ⋅ yr−1 after 2013 (based upon measured atmospheric concentrations and an assumed atmospheric lifetime). These findings heighten the need to understand processes that could affect the CFC-11 lifetime, including ocean fluxes. We evaluate how ocean uptake and release through 2300 affects CFC-11 lifetimes, emission estimates, and the long-term return of CFC-11 from the ocean reservoir. We show that ocean uptake yields a shorter total lifetime and larger inferred emission of atmospheric CFC-11 from 1930 to 2075 compared to estimates using only atmospheric processes. Ocean flux changes over time result in small but not completely negligible effects on the calculated unexpected emissions change (decreasing it by 0.4 ± 0.3 Gg ⋅ yr−1). Moreover, it is expected that the ocean will eventually become a source of CFC-11, increasing its total lifetime thereafter. Ocean outgassing should produce detectable increases in global atmospheric CFC-11 abundances by the mid-2100s, with emission of around 0.5 Gg ⋅ yr−1; this should not be confused with illicit production at that time. An illustrative model projection suggests that climate change is expected to make the ocean a weaker reservoir for CFC-11, advancing the detectable change in the global atmospheric mixing ratio by about 5 yr.

Item Type: Article
Additional Information: Data Availability Statement: The MITgcm output under different forcing runs and the code used here are available publicly on Zenodo (DOI: 10.5281/zenodo.4435502). Acknowledgments: The authors appreciate the CFCs data provided by Matthew Rigby. P.W., S.S., and M.L. gratefully acknowledge support by a grant from VoLo foundation. S.S. and D.W.J.T. appreciate support under NSF-1848863. A.R.B. appreciates support from Simons Foundation Grant 622065. T.D. acknowledges NSF OCE-1948955. We are grateful for feedback from Ray Weiss.
Uncontrolled Keywords: sdg 13 - climate action ,/dk/atira/pure/sustainabledevelopmentgoals/climate_action
Faculty \ School: Faculty of Science > School of Environmental Sciences
UEA Research Groups: Faculty of Science > Research Groups > Centre for Ocean and Atmospheric Sciences
Faculty of Science > Research Groups > Climatic Research Unit
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Depositing User: LivePure Connector
Date Deposited: 07 Jun 2022 09:30
Last Modified: 15 Jun 2023 04:31
URI: https://ueaeprints.uea.ac.uk/id/eprint/85383
DOI: 10.1073/PNAS.2021528118


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