Evidence of a recent decline in UK emissions of hydrofluorocarbons determined by the InTEM inverse model and atmospheric measurements

Abstract. National greenhouse gas inventories (GHGIs) are submitted annually to the United Nations Framework Convention on Climate Change (UNFCCC). They estimated in compliance with Intergovernmental Panel (IPCC) methodological guidance using activity data, emission factors and facility-level measurements. For some sources, outputs from these calculations very uncertain. Inverse modelling techniques that use high-quality, long-term measurements of atmospheric gases have been developed provide independent verification national GHGIs. This is considered good practice by IPCC as it helps inventory compilers verify reported emissions reduce uncertainty. Emission estimates InTEM (Inversion Technique for Modelling) model presented UK hydrofluorocarbons (HFCs) UNFCCC (HFC-125, HFC-134a, HFC-143a, HFC-152a, HFC-23, HFC-32, HFC-227ea, HFC-245fa, HFC-43-10mee HFC-365mfc). These HFCs high global warming potentials (GWPs), background mole fractions all but two increasing, thus highlighting their relevance climate a need increasing accuracy estimation regulatory purposes. study presents evidence annual increase growth HFC-134a has stopped now decreasing. HFC-32 there an early indication, its rapid period ended, HFC-125 slowed 2018. The inverse results indicate implementation European Union regulation HFC successful initiating decline Comparison total 2020 average 2009–2012 shows drop 35 %, indicating progress toward target 79 % decrease sales 2030. (2008–2018) 73 (62–83) of, or 4.3 (2.7–5.9) Tg CO2-eq yr−1 lower than, GHGI. There also significant discrepancies between individual HFCs.