Megan He: Attributing 2019–2024 global methane growth using TROPOMI satellite observations
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Abstract
Atmospheric methane concentrations increased at a rate of 0.7% a-1 over 2019–2024 but the causes are unclear. We conducted an analytical inversion of bias-corrected TROPOspheric Monitoring Instrument (TROPOMI) satellite observations to quantify 2019–2024 annual mean methane emissions and hemispheric OH concentrations. We find that the methane rise from 2019 to 2024 reflects an approach to steady state between 2019 sources and sinks (59% of the rise), augmented by increasing emissions (25%) and decreasing OH concentrations (16%). Global emissions increased from 571 Tg a-1 in 2019 to 601 Tg a-1 in 2021 and back to 575 Tg a-1 in 2024. 2019–2024 emission decreases from oil/gas and rice were offset by increases from livestock and waste. East Africa and South America were most responsible for the 2019–2024 increase in emissions. The methane trend over 2022–2024 was driven mostly by increasing OH rather than decreasing emissions.
Bio
Megan He is a PhD student in Professor Daniel Jacob’s Atmospheric Chemistry Modeling Group at Harvard University. Her research uses models to explain the global rise in methane concentrations, and she is also interested in connecting these findings to air quality and science policy. She holds a master’s degree in public policy from Cambridge University and a bachelor’s degree in Environmental Engineering and Global Affairs from Yale University.