Atmospheric modelling shows European HFC emissions are decreasing

A recent study by De Longueville et al. [1] reports generally good agreement in recent years for HFC emissions over north-western Europe between emissions derived from atmospheric modelling (top-down) and national inventories (bottom up). The study presents trends of HFC emissions across north-western Europe (UK, France, Germany, Ireland, Belgium, the Netherlands and Luxembourg) between 2013 and 2024, derived from atmospheric modelling using atmospheric measurements at eleven monitoring stations. Although global emissions continue to rise for most HFCs, in north-western Europe, results show an overall steady decline in total HFC emissions following EU F-gas Regulations. This reduction is driven primarily by decreasing emissions of HFC-134a, HFC-143a and HFC-125, but with increasing HFC-32 emissions used to replace R-410A.

Comparisons with national inventories reported to the United Nations Framework Convention on Climate Change (UNFCCC) show generally good agreement over north-western Europe but reveal discrepancies for specific compounds and countries, particularly in earlier years of the period. The study compared emissions from atmospheric modelling with emissions reported in the National Inventory Documents (NID) submitted to the UNFCCC in 2025, taken from the Common Reporting Tables. Overall, both the atmospheric derived emissions and the inventories indicate a substantial regional decline in total HFC emissions since 2017, although inventories tend to estimate larger emissions in the earlier years compared to the atmospheric based emission estimates.

The study derived long-term emission estimates of eleven HFCs, namely HFC-134a, HFC-143a, HFC-125, HFC-32, HFC-23, HFC-227ea, HFC-365mfc, HFC-245fa, HFC-152a, HFC-236fa and HFC-4310mee, for the period 2013–2024. Total HFC emissions (inventory and atmospheric observation-based) in north-western Europe, are relatively stable through 2013–2016 before declining steadily from 2016 onward. This behaviour closely mirrors that of HFC-134a, the dominant contributor to regional HFC emissions, accounting for approximately 38% of the total, based on 2023 atmospheric measurement inferred emissions, followed by HFC-125 (31 %) and HFC-143a (18 %).  Total HFC emissions from north-western Europe in 2023 represented 2% of global emissions.

Another study by Annadate et al. [2] reported Italian HFC-134a emissions using observations from four stations finding a similar decreasing trend in Italy after 2015, highlighting the effect of European regulation on fluorinated gases that came into force in 2014. Comparison with the Italian National Emission Inventory indicated an improvement in bottom-up estimates, with the 2024 inventory emission trend post-2015 aligning closely with the atmospheric modelling emission results.  This paper also studied HFC-134a emissions spanning more European countries than considered by De Longueville et al. [1] , with modelled emissions show a consistent decline of 27% between 2016 and 2023.

The paper by De Longueville et al. [1] explained that HFC-23 presents particular challenges for atmospheric modelling. It is emitted primarily as a by-product of HCFC-22 production where its emissions may be sporadic, and highly localised; features that are difficult to capture with the temporal and spatial resolution of the modelling systems and the current measurement density used in the study. The study reported that HFC-23 shows substantial year-to-year variability and comparatively large uncertainties in the atmospheric modelling estimates. Although a downward tendency appears after 2022, the paper commented that extending the timeseries will be important to confirm whether this represents a sustained decline in atmospheric observation based emissions. The inventory, by contrast, shows a sharp reduction after 2018.

References

1. De Longueville, H., Melo, D. B., Redington, A. L., Ramsden, A., Danjou, A., Andrews, P., Pitt, J., Murphy, B., Constantin, L., Stanley, K. M., O'Doherty, S., Wenger, A., Young, D., Engel, A., Schuck, T., Meixner, K., Wagenhaeuser, T., Gad, F., Vollmer, M. K., Reimann, S., Maoine, M., Arduini, J., Lunder, C., Schmidtbauer, N., Haszpra, L., Molnár, M., Frumau, A., Couret, C., Rigby, M., Henne, S., Manning, A., and Ganesan, A. L.: European HFC emissions evaluated with multiple atmospheric inverse models and UNFCCC national inventories, Atmos. Chem. Phys., 26, 7647–7675, https://doi.org/10.5194/acp-26-7647-2026, 2026
2. Annadate, S., Mancinelli, E., Gonella, B., Moricci, F., O’Doherty, S., Stanley, K., Young, D., Vollmer, M. K., Cesari, R., Falasca, S., Giostra, U., Maione, M., and Arduini, J.: Monitoring the impact of EU F-gas regulation on HFC-134a emissions through a comparison of top-down and bottom-up estimates, Environmental Sciences Europe, 37, https://doi.org/10.1186/s12302-025-01081-1, 2025.