Quantifying the Efficiency of Stratospheric Aerosol Geoengineering at Different Altitudes

Abstract Stratospheric aerosol injection (SAI) of reflective sulfate aerosols has been proposed to temporarily reduce the impacts of global warming. In this study, we compare two SAI simulations which inject at different altitudes to provide the same amount of cooling, finding that lower‐altitude SA...

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Main Authors: Walker R. Lee, Daniele Visioni, Ewa M. Bednarz, Douglas G. MacMartin, Ben Kravitz, Simone Tilmes
Format: Article
Language:English
Published: Wiley 2023-07-01
Series:Geophysical Research Letters
Subjects:
Online Access:https://doi.org/10.1029/2023GL104417
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author Walker R. Lee
Daniele Visioni
Ewa M. Bednarz
Douglas G. MacMartin
Ben Kravitz
Simone Tilmes
author_facet Walker R. Lee
Daniele Visioni
Ewa M. Bednarz
Douglas G. MacMartin
Ben Kravitz
Simone Tilmes
author_sort Walker R. Lee
collection DOAJ
description Abstract Stratospheric aerosol injection (SAI) of reflective sulfate aerosols has been proposed to temporarily reduce the impacts of global warming. In this study, we compare two SAI simulations which inject at different altitudes to provide the same amount of cooling, finding that lower‐altitude SAI requires 64% more injection. SAI at higher altitudes cools the surface more efficiently per unit injection than lower‐altitude SAI through two primary mechanisms: the longer lifetimes of SO2 and SO4 at higher altitudes, and the water vapor feedback, in which lower‐altitude SAI causes more heating in the tropical cold point tropopause region, thereby increasing water vapor transport into the stratosphere and trapping more terrestrial infrared radiation that offsets some of the direct aerosol‐induced cooling. We isolate these individual mechanisms and find that the contribution of lifetime effects to differences in cooling efficiency is approximately five to six times larger than the contribution of the water vapor feedback.
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series Geophysical Research Letters
spelling doaj-art-b93b751d1933495ea5d0b23481fb3aad2025-08-20T02:11:57ZengWileyGeophysical Research Letters0094-82761944-80072023-07-015014n/an/a10.1029/2023GL104417Quantifying the Efficiency of Stratospheric Aerosol Geoengineering at Different AltitudesWalker R. Lee0Daniele Visioni1Ewa M. Bednarz2Douglas G. MacMartin3Ben Kravitz4Simone Tilmes5Sibley School of Mechanical and Aerospace Engineering Cornell University Ithaca NY USASibley School of Mechanical and Aerospace Engineering Cornell University Ithaca NY USASibley School of Mechanical and Aerospace Engineering Cornell University Ithaca NY USASibley School of Mechanical and Aerospace Engineering Cornell University Ithaca NY USADepartment of Earth and Atmospheric Sciences Indiana University Bloomington IN USAAtmospheric Chemistry, Observations, and Modeling Lab National Center for Atmospheric Research Boulder CO USAAbstract Stratospheric aerosol injection (SAI) of reflective sulfate aerosols has been proposed to temporarily reduce the impacts of global warming. In this study, we compare two SAI simulations which inject at different altitudes to provide the same amount of cooling, finding that lower‐altitude SAI requires 64% more injection. SAI at higher altitudes cools the surface more efficiently per unit injection than lower‐altitude SAI through two primary mechanisms: the longer lifetimes of SO2 and SO4 at higher altitudes, and the water vapor feedback, in which lower‐altitude SAI causes more heating in the tropical cold point tropopause region, thereby increasing water vapor transport into the stratosphere and trapping more terrestrial infrared radiation that offsets some of the direct aerosol‐induced cooling. We isolate these individual mechanisms and find that the contribution of lifetime effects to differences in cooling efficiency is approximately five to six times larger than the contribution of the water vapor feedback.https://doi.org/10.1029/2023GL104417geoengineeringstratospheric aerosol injectionsolar geoengineeringsolar radiation managementclimate intervention
spellingShingle Walker R. Lee
Daniele Visioni
Ewa M. Bednarz
Douglas G. MacMartin
Ben Kravitz
Simone Tilmes
Quantifying the Efficiency of Stratospheric Aerosol Geoengineering at Different Altitudes
Geophysical Research Letters
geoengineering
stratospheric aerosol injection
solar geoengineering
solar radiation management
climate intervention
title Quantifying the Efficiency of Stratospheric Aerosol Geoengineering at Different Altitudes
title_full Quantifying the Efficiency of Stratospheric Aerosol Geoengineering at Different Altitudes
title_fullStr Quantifying the Efficiency of Stratospheric Aerosol Geoengineering at Different Altitudes
title_full_unstemmed Quantifying the Efficiency of Stratospheric Aerosol Geoengineering at Different Altitudes
title_short Quantifying the Efficiency of Stratospheric Aerosol Geoengineering at Different Altitudes
title_sort quantifying the efficiency of stratospheric aerosol geoengineering at different altitudes
topic geoengineering
stratospheric aerosol injection
solar geoengineering
solar radiation management
climate intervention
url https://doi.org/10.1029/2023GL104417
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