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Attribution of the 2020 surge in atmospheric methane by inverse analysis of GOSAT observations
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  • Zhen Qu,
  • Daniel Jacob,
  • Yuzhong Zhang,
  • Lu Shen,
  • Daniel J Varon,
  • Xiao Lu,
  • Tia Scarpelli,
  • Anthony Bloom,
  • John Worden,
  • Robert J Parker
Zhen Qu
Harvard University

Corresponding Author:[email protected]

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Daniel Jacob
Harvard University
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Yuzhong Zhang
Westlake University
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Lu Shen
Peking University
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Daniel J Varon
Harvard University
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Xiao Lu
Sun Yat-sen University
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Tia Scarpelli
Harvard University
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Anthony Bloom
California Institute of Technology
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John Worden
California Institute of Technology
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Robert J Parker
University of Leicester
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Abstract

Atmospheric methane mixing ratio rose by 15 ppbv between 2019 and 2020, the fastest growth rate on record. We conduct a global inverse analysis of 2019-2020 GOSAT satellite observations of atmospheric methane to analyze the combination of sources and sinks driving this surge. The atmospheric methane growth rate increased by 31 Tg a-1 from 2019 to 2020, representing a 36 Tg a-1 forcing on the methane budget away from steady state. 86% of the forcing in the base inversion is from increasing emissions (82 ± 18% in the 9-member inversion ensemble), and 14% is from decrease in tropospheric OH. Half of the increase in emissions is from Africa (15 Tg a-1) and appears to be driven by wetland inundation. There is also a large relative increase in emissions from Canada and Alaska (4.8 Tg a-1 , 24%) that could be driven by temperature sensitivity of boreal wetland emissions.