Evidence of a recent decline in UK emissions of hydrofluorocarbons determined...

Manning, A., A. L. Redington, D. Say, S. O’Doherty, D. Young, P. G. Simmonds, M. K. Vollmer, J. Mühle, J. Arduini, G. Spain, A. Wisher, M. Maione, T. J. Schuck, K. Stanley, S. Reimann, A. Engel, P. B. Krummel, P. Fraser, C. M. Harth, P. K. Salameh, R. Weiss, R. Gluckman, P. N. Brown, J. D. Watterson, and T. Arnold (2021), Evidence of a recent decline in UK emissions of hydrofluorocarbons determined by the InTEM inverse model and atmospheric measurements, Atmos. Chem. Phys., 21, 12739-12755, doi:10.5194/acp-21-12739-2021.

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, HFC134a, 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

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Atmospheric Composition Modeling and Analysis Program (ACMAP)
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The operations of Mace Head and Tacolneston 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.