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Sensitivity of tropospheric oxidants to biomass burning emissions: implications for radiative forcing

Mao, Jingqiu; Horowitz, Larry W.; Naik, Vaishali; Fan, Songmiao; Liu, Junfeng; Fiore, Arlene M.

Biomass burning is one of the largest sources of trace gases and aerosols to the atmosphere and has profound influence on tropospheric oxidants and radiative forcing. Using a fully coupled chemistry-climate model (GFDL AM3), we find that co-emission of trace gases and aerosol from present-day biomass burning increases the global tropospheric ozone burden by 5.1% and decreases global mean OH by 6.3%. Gas and aerosol emissions combine to increase CH4 lifetime nonlinearly. Heterogeneous processes are shown to contribute partly to the observed lower ΔO3/ΔCO ratios in northern high latitudes versus tropical regions. The radiative forcing from biomass burning is shown to vary nonlinearly with biomass burning strength. At present-day emission levels, biomass burning produces a net radiative forcing of −0.19 W/m2 (−0.29 from short-lived species, mostly aerosol direct and indirect effects, +0.10 from CH4- and CH4-induced changes in O3 and stratospheric H2O) but increases emissions to over 5 times present levels would result in a positive net forcing.

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Also Published In

Title
Geophysical Research Letters
DOI
https://doi.org/10.1002/grl.50210

More About This Work

Academic Units
Earth and Environmental Sciences
Lamont-Doherty Earth Observatory
Ocean and Climate Physics
Publisher
American Geophysical Union
Published Here
November 18, 2015