More Like this

1. California Dominates U.S. Emissions of Sulfuryl Fluoride, a Synthetic Pesticide and Potent Greenhouse Gas

   Gaeta, Dylan C; Mille, Scot M; Mühle, Jens; Vimont, Isaac J; Crotwell, Molly; Hu, Lei; Miller, John; McKain, Kathryn; Baier, Bianca C; Zhang, Mingyang; et al (January 2024, American Meteorological Society 104th Annual Meeting Abstracts)

   Sulfuryl fluoride (SO2F2) is a synthetic pesticide and a potent greenhouse gas (GHG) that is accumulating in the global atmosphere. SO2F2 has been increasingly used for agricultural and structural fumigation worldwide to replace methyl bromide (CH3Br), which was largely phased out under the Montreal Protocol to protect the ozone layer. Rising emissions of SO2F2 are concerning due to its relatively long atmospheric lifetime and high global warming potential (GWP). However, 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. We provide an atmospheric measurement-based constraint on 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. SO F emissions, at a rate of 0.26 (+/-0.10) Gg yr-1 . Furthermore, we estimate that emissions of SO F from California are equal to 5.5-12% of global SO2F2 emissions -- a large contribution from a single state. 

   more » « less
2. Constraining U.S. Sulfuryl Fluoride Emissions With Atmospheric Measurements and a Geostatistical Inverse Model

   Gaeta, Dylan C; Muhle, Jens; Vimont, Isaac J; Crotwell, Molly; McKain, Kathryn; Baier, Bianca; Miller, John B; Zhang, Mingyang; Bao, Jianing; Miller, Benjamin R; et al (December 2022, American Geophysical Union 2022 Fall Meeting Abstracs)

   The mean abundance of sulfuryl fluoride (SO2F2) in the global atmosphere has been increasing since at least the 1970s, with ambient air mole fractions exceeding 2.5 parts per trillion (ppt) today. SO2F2 is a synthetic pesticide and a potent greenhouse gas (GHG) used for fumigation - predominantly of wooden structures, and increasingly for agricultural and commodity products as well. Worldwide use of SO2F2 has surged since the use of methyl bromide (CH3Br) for fumigation was largely phased out under the Montreal Protocol. Recent atmospheric measurements and modeling work from the Advanced Global Atmospheric Gases Experiment (AGAGE) indicates that global emissions of SO2F2 have reached a historic high in recent years at roughly 3.0 Gg SO2F2 yr-1. However, under the current UNFCCC emissions reporting guidelines, countries are not required to report their emissions of SO2F2, and thus SO2F2 is not included in most national GHG emissions inventories, leading to a scarcity of information on the global distribution and magnitude of SO2F2 emissions. In the U.S., California is the only state that keeps a public record of statewide SO2F2 use, despite the gas being used for termite fumigation in other warm-climate coastal states such as Florida. To fill this information gap, we use flask-sample measurements of SO2F2 from the NOAA Global Greenhouse Gas Reference Network (GGGRN) and a geostatistical inverse model (GIM) to provide a measurement-based top-down constraint on the magnitude and spatial distribution of SO2F2 emissions across the continental U.S. We find that California emits the vast majority (>90%) of U.S. SO2F2 emissions, with the largest emissions coming from the California South Coast (Los Angeles, Orange, and San Diego Counties), and the second largest from the San Francisco Bay Area. Outside of California, SO2F2 emissions are rarely detected by the NOAA GGGRN. However, despite California's oversized contribution to U.S. SO2F2 emissions, a significantly large fraction (>50%) of the 3.0 Gg yr-1 global emissions budget is still emitted elsewhere. We will present insights gained from the NOAA GGGRN measurements and our inverse modeling work, including a case study on California's SO2F2 emissions and reconciliation with California state SO2F2 usage records. 

   more » « less
3. Isotopic Constraints on Nitrous Oxide Emissions From the US Corn Belt

   https://doi.org/10.1029/2024GL109623  

   Griffis, T J; Yu, Z; Baker, J M; Millet, D B (November 2024, Geophysical Research Letters)

   Abstract Agriculture is the dominant source of anthropogenic nitrous oxide (N₂O) –a greenhouse gas and a stratospheric ozone depleting substance. The US Corn Belt is a large global N₂O source, but there remain large uncertainties regarding its source attribution and biogeochemical pathways. Here, we interpret high frequency stable N₂O isotope observations from a very tall tower to improve our understanding of regional source attribution. We detected significant seasonal variability in δ¹⁵N_bulk(6.47–7.33‰) and the isotope site preference (δ¹⁵N^SP = δ¹⁵N^α–δ¹⁵N^β, 18.22–25.19‰) indicating a predominance of denitrification during the growing period but of nitrification during the snowmelt period. Isotope mixing models and atmospheric inversions both indicate that indirect emissions contribute substantially (>35%) to total N₂O emissions. Despite the relatively large uncertainties, the upper bound of bottom‐up indirect emission estimates are at the lower bound of the isotopic constraint, implying significant discrepancies that require further investigation. 

   more » « less
4. Increased nitrous oxide emissions from global lakes and reservoirs since the pre-industrial era

   https://doi.org/10.1038/s41467-024-45061-0  

   Li, Ya; Tian, Hanqin; Yao, Yuanzhi; Shi, Hao; Bian, Zihao; Shi, Yu; Wang, Siyuan; Maavara, Taylor; Lauerwald, Ronny; Pan, Shufen (December 2024, Nature Communications)

   Abstract Lentic systems (lakes and reservoirs) are emission hotpots of nitrous oxide (N₂O), a potent greenhouse gas; however, this has not been well quantified yet. Here we examine how multiple environmental forcings have affected N₂O emissions from global lentic systems since the pre-industrial period. Our results show that global lentic systems emitted 64.6 ± 12.1 Gg N₂O-N yr⁻¹in the 2010s, increased by 126% since the 1850s. The significance of small lentic systems on mitigating N₂O emissions is highlighted due to their substantial emission rates and response to terrestrial environmental changes. Incorporated with riverine emissions, this study indicates that N₂O emissions from global inland waters in the 2010s was 319.6 ± 58.2 Gg N yr⁻¹. This suggests a global emission factor of 0.051% for inland water N₂O emissions relative to agricultural nitrogen applications and provides the country-level emission factors (ranging from 0 to 0.341%) for improving the methodology for national greenhouse gas emission inventories. 

   more » « less
5. Impacts of Volcanic Emissions on the Global Biogeochemical Mercury Cycle: Insights From Satellite Observations and Chemical Transport Modeling

   https://doi.org/10.1029/2023GL104667  

   Geyman, Benjamin M; Thackray, Colin P; Jacob, Daniel J; Sunderland, Elsie M (November 2023, Geophysical Research Letters)

   Abstract Volcanism is the largest natural source of mercury (Hg) to the biosphere. However, past Hg emission estimates have varied by three orders of magnitude. Here, we present an updated central estimate and interquartile range (232 Mg a⁻¹; IQR: 170–336 Mg a⁻¹) for modern volcanic Hg emissions based on advances in satellite remote sensing of sulfur dioxide (SO₂) and an improved method for considering uncertainty in Hg:SO₂emissions ratios. Atmospheric modeling shows the influence of volcanic Hg on surface atmospheric concentrations in the extratropical Northern Hemisphere is 1.8 times higher than in the Southern Hemisphere. Spatiotemporal variability in volcanic Hg emissions may obscure atmospheric trends forced by anthropogenic emissions at some locations. This should be considered when selecting monitoring sites to inform global regulatory actions. Volcanic emission estimates from this work suggest the pre‐anthropogenic global atmospheric Hg reservoir was 580 Mg, 7‐fold lower than in 2015 (4,000 Mg). 

   more » « less