Editing IPCC:AR6/WGI/Chapter-2 (section)

==== 2.2.4.1 Chlorofluorocarbons (CFCs) ====

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Atmospheric abundances of most CFCs have continued to decline since 2011 (AR5). The globally-averaged abundance of CFC-12 decreased by 25 ppt (4.8%) from 2011 to 2019, while CFC-11 decreased by about 11 ppt (4.7%) over the same period (Table 2.2 and Figure 2.6). Atmospheric abundances of some minor CFCs (CFC-13, CFC-115, CFC-113a) have increased since 2011 (Annex III), possibly related to use of HFCs ( [[#Laube--2014|Laube et al., 2014]] ). Overall, as of 2019 the ERF from CFCs has declined by 9 ± 0.5% from its maximum in 2000, and 4.7 ± 0.6% since 2011 (Table 7.5).

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'''Figure 2.6''' '''|''' '''Global mean atmospheric mixing ratios of select ozone-depleting''' '''substances and other greenhouse gases.''' Data shown are based on the CMIP6 historical dataset and data from NOAA and AGAGE global networks. PFCs include CF <sub>4</sub> , C <sub>2</sub> f <sub>6</sub> , and C <sub>3</sub> F <sub>8</sub> , and ''c'' -C <sub>4</sub> F <sub>8</sub> ; Halons include halon-1211, halon-1301, and halon-2402; other HFCs include HFC-23, HFC-32, HFC-125, HFC-143a, HFC-152a, HFC-227ea, HFC-236fa, HFC-245fa, and HFC-365mfc, and HFC-43-10mee. Note that the y-axis range is different for '''(a)''' , '''(b)''' and '''(c)''' and a 25 parts per trillion (ppt) yardstick is given next to each panel to aid interpretation. Further data are in [[IPCC:Wg1:Chapter:Annex-iii|Annex III]] and details on data sources and processing are available in the chapter data table (Table 2.SM.1).

While global reporting indicated that CFC-11 production had essentially ceased by 2010, and the atmospheric abundance of CFC-11 is still decreasing, emissions inferred from atmospheric observations began increasing in 2013–2014 and remained elevated for 5–6 years, suggesting renewed and unreported production ( [[#Montzka--2018a|Montzka et al., 2018a]] , 2021; [[#Rigby--2019|Rigby et al., 2019]] ; [[#Park--2021|Park et al., 2021]] ). The global lifetimes of several ozone-depleting substances have been updated (SPARC, 2013), in particular for CFC-11 from 45 to 52 years.

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