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High-frequency, in situ global observations of HCFC-22 (CHClF2),HCFC-141b (CH3CCl2F), HCFC-142b (CH3CClF2) and HCFC-124(CHClFCF3) and their main HFC replacements, HFC-134a(CH2FCF3), HFC-125 (CHF2CF3), HFC-143a (CH3CF3)and HFC-32 (CH2F2), have been used to determine their changingglobal growth rates and emissions in response to the Montreal Protocol andits recent amendments. Global mean mole fractions of HCFC-22, -141b, and-142b have increased throughout the observation period, reaching 234, 24.3 and22.4 pmol mol−1, respectively, in 2015. HCFC-124 reached a maximumglobal mean mole fraction of 1.48 pmol mol−1 in 2007 and has sincedeclined by 23 % to 1.14 pmol mol−1 in 2015. The HFCs all showincreasing global mean mole fractions. In 2015 the global mean mole fractions(pmol mol−1) were 83.3 (HFC-134a), 18.4 (HFC-125), 17.7 (HFC-143a) and10.5 (HFC-32). The 2007 adjustment to the Montreal Protocol required the acceleratedphase-out of emissive uses of HCFCs with global production and consumptioncapped in 2013 to mitigate their environmental impact as both ozone-depleting substances and important greenhouse gases. We find that this changehas coincided with a stabilisation, or moderate reduction, in globalemissions of the four HCFCs with aggregated global emissions in 2015 of449 ± 75 Gg yr−1, in CO2 equivalent units(CO2 eq.)0.76 ± 0.1 Gt yr−1, compared with 483 ± 70 Gg yr−1(0.82 ± 0.1 Gt yr−1 CO2 eq.) in 2010 (uncertainties are1σ throughout this paper). About 79 % of the total HCFCatmospheric burden in 2015 is HCFC-22, where global emissions appear to havebeen relatively similar since 2011, in spite of the 2013 cap on emissiveuses. We attribute this to a probable increase in production and consumptionof HCFC-22 in Montreal Protocol Article 5 (developing) countries and thecontinuing release of HCFC-22 from the large banks which dominate HCFC globalemissions. Conversely, the four HFCs all show increasing mole fraction growthrates with aggregated global HFC emissions of 327 ± 70 Gg yr−1(0.65 ± 0.12 Gt yr−1 CO2 eq.) in 2015 compared to240 ± 50 Gg yr−1(0.47 ± 0.08 Gt yr−1 CO2 eq.) in 2010. We also note thatemissions of HFC-125 and HFC-32 appear to have increased more rapidlyaveraged over the 5-year period 2011–2015, compared to 2006–2010. As notedby Lunt et al. (2015) this may reflect a change to refrigerant blends, suchas R-410A, which contain HFC-32 and -125 as a 50 : 50 blend

Changing trends and emissions of hydrochlorofluorocarbons (HCFCs) and their hydrofluorocarbon (HFCs) replacements