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

Sulfuryl fluoride (SO 2 F 2 ) is a synthetic pesticide and a potent greenhouse gas that is accumulating in the global atmosphere. Rising emissions are a concern since SO 2 F 2 has a relatively long atmospheric lifetime and a high global warming potential. The U.S. is thought to contribute substantially to global SO 2 F 2 emissions, but there is a paucity of information on how emissions of SO 2 F 2 are distributed across the U.S., and there is currently no inventory of SO 2 F 2 emissions for the U.S. or individual states. Here we provide an atmospheric measurement-based estimate of U.S. SO 2 F 2 emissions using high-precision SO 2 F 2 measurements from the NOAA Global Greenhouse Gas Reference Network (GGGRN) and a geostatistical inverse model. We find that California has the largest SO 2 F 2 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 SO 2 F 2 emissions are detected by our analysis of GGGRN data. We find that California emits 60-85% of U.S. SO 2 F 2 emissions, at a rate of 0.26 ( ± 0.10) Gg yr −1 . We estimate that emissions of SO 2 F 2 from California are equal to 5.5–12% of global SO 2 F 2 emissions.