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

doi:10.1029/2019GL085838

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

Research output: Journal article publication › Journal article › Academic research › peer-review

32 Citations (Scopus)

Abstract

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 (Cl_y) and bromine (Br_y). 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 Cl_y and Br_y 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 language	English
Article number	e2019GL085838
Journal	Geophysical Research Letters
Volume	47
Issue number	4
DOIs	https://doi.org/10.1029/2019GL085838
Publication status	Published - 28 Feb 2020
Externally published	Yes

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

SDG 14 Life Below Water

Keywords

atmospheric chemistry
geoengineering
marine cloud brightening
reactive halogens
sea salt aerosols

ASJC Scopus subject areas

Geophysics
General Earth and Planetary Sciences

More information

10.1029/2019GL085838

Cite this

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

abstract = "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 (\textasciitilde{}2\%) but may have potential implications for surface ozone pollution in tropical coastal regions.",

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note = "Funding Information: Model data are available at the University of Washington ResearchWorks repository: http://hdl.handle.net/1773/44939. H. M. H. acknowledges support from NSF AGS Postdoctoral Fellowship (grant 1624738) during the course of this study. A. W. acknowledges funding from the Washington NASA Space Grant Consortium. C. D. H. acknowledges support from the NASA New Investigator Program (grant NNX16AI57G). We thank Robert Wood and Philip Rasch for helpful discussions, and three anonymous reviewers for their feedback. Publisher Copyright: {\textcopyright} 2020. The Authors. Copyright: Copyright 2020 Elsevier B.V., All rights reserved.",

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Effects of Sea Salt Aerosol Emissions for Marine Cloud Brightening on Atmospheric Chemistry: Implications for Radiative Forcing. / Horowitz, Hannah M.; Holmes, Christopher; Wright, Alicia et al.
In: Geophysical Research Letters, Vol. 47, No. 4, e2019GL085838, 28.02.2020.

Research output: Journal article publication › Journal article › Academic research › peer-review

TY - JOUR

T1 - Effects of Sea Salt Aerosol Emissions for Marine Cloud Brightening on Atmospheric Chemistry

T2 - Implications for Radiative Forcing

AU - Horowitz, Hannah M.

AU - Holmes, Christopher

AU - Wright, Alicia

AU - Sherwen, Tomás

AU - Wang, Xuan

AU - Evans, Mat

AU - Huang, Jiayue

AU - Jaeglé, Lyatt

AU - Chen, Qianjie

AU - Zhai, Shuting

AU - Alexander, Becky

N1 - Funding Information: Model data are available at the University of Washington ResearchWorks repository: http://hdl.handle.net/1773/44939. H. M. H. acknowledges support from NSF AGS Postdoctoral Fellowship (grant 1624738) during the course of this study. A. W. acknowledges funding from the Washington NASA Space Grant Consortium. C. D. H. acknowledges support from the NASA New Investigator Program (grant NNX16AI57G). We thank Robert Wood and Philip Rasch for helpful discussions, and three anonymous reviewers for their feedback. Publisher Copyright: © 2020. The Authors. Copyright: Copyright 2020 Elsevier B.V., All rights reserved.

PY - 2020/2/28

Y1 - 2020/2/28

N2 - 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.

AB - 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.

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KW - geoengineering

KW - marine cloud brightening

KW - reactive halogens

KW - sea salt aerosols

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DO - 10.1029/2019GL085838

M3 - Journal article

AN - SCOPUS:85081074057

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VL - 47

JO - Geophysical Research Letters

JF - Geophysical Research Letters

IS - 4

M1 - e2019GL085838

ER -

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

Abstract

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Keywords

ASJC Scopus subject areas

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