Replacing Methyl Bromide with Sulfuryl Fluoride: Long-Term Trends in European Fumigant Emissions

Methyl bromide (CH₃Br) and sulfuryl fluoride (SO₂F₂) are widely used fumigants in agriculture and quarantine and pre-shipment activities, leading to atmospheric emissions. While methyl bromide is both anthropogenic and naturally emitted, its regulation under the Montreal Protocol has driven a strong decline in use due to its ozone-depleting potential (ODP = 0.57) and short atmospheric lifetime (~0.8 years). In contrast, SO₂F₂ has increasingly been adopted as a replacement for CH₃Br and is a potent greenhouse gas, with a 100-year global warming potential of 4090.

We present an observation-based analysis of European emissions of CH₃Br and SO₂F₂ covering the period 2003–2023. Emissions are quantified using long-term atmospheric measurements from four European stations combined with an atmospheric transport model and an inversion framework. Our results show a marked decline in CH₃Br emissions consistent with regulatory controls, alongside a rise in SO₂F₂ emissions until around 2020.

This study provides the first long-term, top-down assessment of European SO₂F₂ emissions and evaluates regulatory compliance for CH₃Br. The findings highlight the importance of sustained atmospheric monitoring to track substitution effects and assess the climate implications of ozone-safe but high-GWP alternatives.