National greenhouse gas inventories (GHGIs) are submitted annually to the United Nations Framework Convention on Climate Change (UNFCCC). They are estimated in compliance with Intergovernmental Panel on Climate Change (IPCC) methodological guidance using activity data, emission factors and facility-level measurements. For some sources, the outputs from these calculations are very uncertain. Inverse modelling techniques that use high-quality, long-term measurements of atmospheric gases have been developed to provide independent verification of national GHGIs. This is considered good practice by the IPCC as it helps national inventory compilers to verify reported emissions and to reduce emission uncertainty. Emission estimates from the InTEM (Inversion Technique for Emission Modelling) model are presented for the UK for the hydrofluorocarbons (HFCs) reported to the UNFCCC (HFC-125, HFC-134a, HFC-143a, HFC-152a, HFC-23, HFC-32, HFC-227ea, HFC-245fa, HFC-43-10mee and HFC-365mfc). These HFCs have high global warming potentials (GWPs), and the global background mole fractions of all but two are increasing, thus highlighting their relevance to the climate and a need for increasing the accuracy of emission estimation for regulatory purposes. This study presents evidence that the long-term annual increase in growth of HFC-134a has stopped and is now decreasing. For HFC-32 there is an early indication, its rapid global growth period has ended, and there is evidence that the annual increase in global growth for HFC-125 has slowed from 2018. The inverse modelling results indicate that the UK implementation of European Union regulation of HFC emissions has been successful in initiating a decline in UK emissions from 2018. Comparison of the total InTEM UK HFC emissions in 2020 with the average from 2009-2012 shows a drop of 35ĝ€¯%, indicating progress toward the target of a 79ĝ€¯% decrease in sales by 2030. The total InTEM HFC emission estimates (2008-2018) are on average 73 (62-83)ĝ€¯% of, or 4.3 (2.7-5.9)ĝ€¯Tgĝ€¯CO2-eqĝ€¯yr-1 lower than, the total HFC emission estimates from the UK GHGI. There are also significant discrepancies between the two estimates for the individual HFCs.
Bibliographical noteFunding Information:
Acknowledgements. We thank the UK Department of Business, Energy and Industrial Strategy (BEIS) (contract no. TRN 1537/06/2018) for supporting the UK DECC network and the analysis of the data. We thank Holly Manning for her help in creating the time series plots. We thank the Science, Technology, Research & Innovation for the Environment (STRIVE) Programme 2007–2013 Climate Change Research Programme (CCRP 2006–2013), and Irish EPA (project no. 07-CCRP-1.1.5a). The Commonwealth Scientific and Industrial Research Organisation (CSIRO, Australia) and Bureau of Meteorology (Australia) are thanked for their ongoing long-term support and funding of the Cape Grim station and the Cape Grim science programme. The operation and calibration of the global AGAGE measurement network are supported by NASA’s Upper Atmosphere Research Program through grants NAG5-12669, NNX07AE89G, NNX11AF17G, and NNX16AC98G to MIT and NNX07AE87G, NNX07AF09G, NNX11AF15G, and NNX11AF16G to SIO. Additional support for operation of the station at Ragged Point, Barbados was provided by National Oceanic and Atmospheric Administration (NOAA) contracts RA-133-R15-CN-0008 and 1305M319CNRMJ0028 (to the University of Bristol). Financial support for the Jungfraujoch measurements is acknowledged from the Swiss national program CLIMGAS-CH (Swiss Federal Office for the Environment, FOEN) and from ICOS-CH (Integrated Carbon Observation System Research Infrastructure). Support for the Jungfraujoch station was provided by International Foundation High Altitude Research Stations Jungfraujoch and Gornergrat (HFSJG).
Financial support. The operations of Mace Head and Tacolne-ston and the data analysis were funded by the UK Department of Business, Energy and Industrial Strategy (BEIS) through contract no. 1537/06/2018 to the University of Bristol. The operation and calibration of the global AGAGE measurement network are supported by NASA’s Upper Atmosphere Research Program through grants NAG5-12669, NNX07AE89G, NNX11AF17G, and NNX16AC98G to MIT and NNX07AE87G, NNX07AF09G, NNX11AF15G, and NNX11AF16G to SIO. Ragged Point was also partly funded by National Oceanic and Atmospheric Administration (NOAA) grant nos. RA-133-R15-CN-0008 and 1305-M319-CNRMJ-0028 to the University of Bristol. Support for the observations at Jungfraujoch comes through Swiss national programmes HALCLIM and CLIMGAS-CH (Swiss Federal Office for the Environment, FOEN), the International Foundation High Altitude Research Stations Jungfraujoch and Gornergrat (HFSJG) and ICOS-CH (Integrated Carbon Observation System Research Infrastructure). Observations at Cape Grim are supported largely by the Australian Bureau of Meteorology, CSIRO and NASA contract NNX16AC98G to MIT with sub-award no. 5710004055 to CSIRO. Operations at the O. Vittori station (Monte Cimone) are supported by the National Research Council of Italy.
© 2021 The Author(s).