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Heckendorn et al 2009: The impact of geoengineering aerosols on stratospheric temperature and ozone Print E-mail
Friday, 13 November 2009 07:16

The impact of geoengineering aerosols on stratospheric temperature and ozone

P Heckendorn et al 2009 Environ. Res. Lett. 4 045108 (12pp)

 

The impact of geoengineering aerosols on stratospheric temperature and ozone

P Heckendorn et al 2009 Environ. Res. Lett. 4 045108 (12pp)   doi: 10.1088/1748-9326/4/4/045108  Help

 
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P Heckendorn1, D Weisenstein2, S Fueglistaler3, B P Luo1, E Rozanov1,4, M Schraner1, L W Thomason5 and T Peter1
1 Institute for Atmospheric and Climate Science, ETH Zurich, 8092 Zurich, Switzerland
2 AER, Lexington, MA, USA
3 DAMTP, University of Cambridge, UK
4 PMOD-WRC, Davos, Switzerland
5 NASA Langley Research Center, Hampton, VA, USA
E-mail: This e-mail address is being protected from spambots. You need JavaScript enabled to view it
Part of Focus on Climate Engineering: Intentional Intervention in the Climate System

Abstract. Anthropogenic 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.

Received 29 May 2009, accepted for publication 28 October 2009
Published 13 November 2009