Effects of Sea Salt Aerosol Emissions for Marine Cloud Brightening on Atmospheric Chemistry: Implications for Radiative Forcing

Hannah M. Horowitz*, Christopher Holmes, Alicia Wright, Tomás Sherwen, Xuan Wang, Mat Evans, Jiayue Huang, Lyatt Jaeglé, Qianjie Chen, Shuting Zhai, Becky Alexander

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Marine cloud brightening (MCB) is proposed to offset global warming by emitting sea salt aerosols to the tropical marine boundary layer, which increases aerosol and cloud albedo. Sea salt aerosol is the main source of tropospheric reactive chlorine (Cly) and bromine (Bry). The effects of additional sea salt on atmospheric chemistry have not been explored. We simulate sea salt aerosol injections for MCB under two scenarios (212–569 Tg/a) in the GEOS-Chem global chemical transport model, only considering their impacts as a halogen source. Globally, tropospheric Cly and Bry increase (20–40%), leading to decreased ozone (−3 to −6%). Consequently, OH decreases (−3 to −5%), which increases the methane lifetime (3–6%). Our results suggest that the chemistry of the additional sea salt leads to minor total radiative forcing compared to that of the sea salt aerosol itself (~2%) but may have potential implications for surface ozone pollution in tropical coastal regions.

Original languageEnglish
Article numbere2019GL085838
Number of pages16
JournalGeophysical Research Letters
Issue number4
Early online date29 Jan 2020
Publication statusPublished - 28 Feb 2020

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  • geoengineering
  • atmospheric chemistry
  • sea salt aerosols
  • reactive halogens
  • marine cloud brightening

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