California dominates U.S. emissions of the pesticide and potent greenhouse gas sulfuryl fluoride

Sulfuryl fluoride (SO2F2) is a synthetic pesticide and a potent greenhouse gas that is accumulating in the global atmosphere. Rising emissions are a concern since SO2F2 has a relatively long atmospheric lifetime and a high global warming potential. The U.S. is thought to contribute substantially to global SO2F2 emissions, but there is a paucity of information on how emissions of SO2F2 are distributed across the U.S., and there is currently no inventory of SO2F2 emissions for the U.S. or individual states. Here we provide an atmospheric measurement-based estimate of U.S. SO2F2 emissions using high-precision SO2F2 measurements from the NOAA Global Greenhouse Gas Reference Network (GGGRN) and a geostatistical inverse model. We find that California has the largest SO2F2 emissions among all U.S. states, with the highest emissions from southern coastal California (Los Angeles, Orange, and San Diego counties). Outside of California, only very small and infrequent SO2F2 emissions are detected by our analysis of GGGRN data. We find that California emits 60-85% of U.S. SO2F2 emissions, at a rate of 0.26 ( ± 0.10) Gg yr−1. We estimate that emissions of SO2F2 from California are equal to 5.5–12% of global SO2F2 emissions. Despite stringent efforts to reduce greenhouse gas emissions, California is the largest emitter of sulfuryl fluoride in the USA, according to atmospheric measurements and an inverse model.