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The Impact of Geoengineering Aerosols on Stratospheric Temperature and OzoneAnthropogenic greenhouse gas emissions are warming the global climate at an unprecedented rate. Significant emission reductions will be required soon to avoid a rapid temperature rise. As a potential interim measure to avoid extreme temperature increase, it has been suggested that Earth's albedo be increased by artificially enhancing stratospheric sulfate aerosols. We use a 3D chemistry climate model, fed by aerosol size distributions from a zonal mean aerosol model, to simulate continuous injection of 1-10 Mt/a into the lower tropical stratosphere. In contrast to the case for all previous work, the particles are predicted to grow to larger sizes than are observed after volcanic eruptions. The reason is the continuous supply of sulfuric acid and hence freshly formed small aerosol particles, which enhance the formation of large aerosol particles by coagulation and, to a lesser extent, by condensation. Owing to their large size, these particles have a reduced albedo. Furthermore, their sedimentation results in a non-linear relationship between stratospheric aerosol burden and annual injection, leading to a reduction of the targeted cooling. More importantly, the sedimenting particles heat the tropical cold point tropopause and, hence, the stratospheric entry mixing ratio of H2O increases. Therefore, geoengineering by means of sulfate aerosols is predicted to accelerate the hydroxyl catalyzed ozone destruction cycles and cause a significant depletion of the ozone layer even though future halogen concentrations will be significantly reduced.
Document ID
Acquisition Source
Document Type
Reprint (Version printed in journal)
Heckendorn, P.
(Eidgenoessische Technische Hochschule Zurich, Switzerland)
Weisenstein, D.
(AER Lexington, MA, United States)
Fueglistaler, S.
(Cambridge Univ. United Kingdom)
Luo, B. P.
(Eidgenoessische Technische Hochschule Zurich, Switzerland)
Rozanov, E.
(Eidgenoessische Technische Hochschule Zurich, Switzerland)
Schraner, M.
(Eidgenoessische Technische Hochschule Zurich, Switzerland)
Peter, T.
(Eidgenoessische Technische Hochschule Zurich, Switzerland)
Thomason, L. W.
(NASA Langley Research Center Hampton, VA, United States)
Date Acquired
August 25, 2013
Publication Date
November 13, 2009
Publication Information
Publication: Environmental Research Letters
Publisher: institute of physics
Volume: 4
Subject Category
Meteorology And Climatology
Funding Number(s)
Distribution Limits

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