Impact of geoengineered aerosols on the troposphere and stratosphere

• Published in: Journal of Geophysical Research - Atmospheres Vol. 114; no. D12; pp. D12305 - n/a
• Main Authors: Tilmes, Simone, Garcia, Rolando R., Kinnison, Douglas E., Gettelman, Andrew, Rasch, Philip J.
• Format: Journal Article
• Language: English
• Published: Washington, DC American Geophysical Union 27-06-2009; Blackwell Publishing Ltd
• Subjects: Atmospheric Composition and Structure; Atmospheric Processes; Climate change and variability; composition and chemistry; constituent transport and chemistry; Earth sciences; Earth, ocean, space; Exact sciences and technology; geoengineering; Middle atmosphere; Radiative processes; stratospheric aerosols; stratospheric chemistry; Volcanic effects; polar regions; Antarctica; stratospheric chemistry; stratospheric aerosols; geoengineering; atmosphere; Atmosphere model; atmospheric precipitation; simulation; climate warming; Model study; Climate models; climate; baseline; recovery; sulfates; troposphere; Stratospheric aerosol; Earth; dynamics; global warming; global change; temperature; Polar region; transient phenomena; injection; stratosphere; climate change; Heterogeneous reaction
• ISSN: 0148-0227; 2169-897X; 2156-2202; 2169-8996
• DOI: 10.1029/2008JD011420

A coupled chemistry climate model, the Whole Atmosphere Community Climate Model was used to perform a transient climate simulation to quantify the impact of geoengineered aerosols on atmospheric processes. In contrast to previous model studies, the impact on stratospheric chemistry, including heterogeneous chemistry in the polar regions, is considered in this simulation. In the geoengineering simulation, a constant stratospheric distribution of volcanic‐sized, liquid sulfate aerosols is imposed in the period 2020–2050, corresponding to an injection of 2 Tg S/a. The aerosol cools the troposphere compared to a baseline simulation. Assuming an Intergovernmental Panel on Climate Change A1B emission scenario, global warming is delayed by about 40 years in the troposphere with respect to the baseline scenario. Large local changes of precipitation and temperatures may occur as a result of geoengineering. Comparison with simulations carried out with the Community Atmosphere Model indicates the importance of stratospheric processes for estimating the impact of stratospheric aerosols on the Earth's climate. Changes in stratospheric dynamics and chemistry, especially faster heterogeneous reactions, reduce the recovery of the ozone layer in middle and high latitudes for the Southern Hemisphere. In the geoengineering case, the recovery of the Antarctic ozone hole is delayed by about 30 years on the basis of this model simulation. For the Northern Hemisphere, a onefold to twofold increase of the chemical ozone depletion occurs owing to a simulated stronger polar vortex and colder temperatures compared to the baseline simulation, in agreement with observational estimates.