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Author(s): Schmidt H, Alterskjær K, Karam DB, Boucher O, Jones A, Kristjansson JE, Niemeier U, Schulz M, Aaheim A, Benduhn F, Lawrence MG, Timmreck C
Published: March, 2012
Publisher: Earth System Dynamics Discussions
DOI: 10.5194/esdd-3-31-2012
Tags: Stratospheric Aerosols, Cloud Brightening, Climate Modelling
URL: http://www.earth-syst-dynam-discuss.net/3/31/2012/esdd-3-31-2012.html
Abstract: In this study we compare the response of four state-of-the-art Earth system models to climate engineering under scenario G1 of the GeoMIP and IMPLICC model intercomparison projects. In G1, the radiative forcing from an instantaneous quadrupling of the CO2 concentration, starting from the preindustrial level, is balanced by a reduction of the solar constant. Model responses to the two counteracting forcings in G1 are compared to the preindustrial climate in terms of global means and regional patterns and their robustness. While the global mean surface air temperature in G1 remains almost unchanged, the meridional temperature gradient is reduced in all models compared to the control simulation. Another robust response is the global reduction of precipitation with strong effects in particular over North and South America and northern Eurasia. It is shown that this reduction is only partly compensated by a reduction in evaporation so that large continental regions are drier in the engineered climate. In comparison to the climate response to a quadrupling of CO2 alone the temperature responses are small in experiment G1. Precipitation responses are, however, of comparable magnitude but in many regions of opposite sign.
Author(s): Schmidt H, Alterskjær K, Bou Karam D, Boucher O, Jones A, Kristjánsson JE, Niemeier U, Schulz M, Aaheim A, Benduhn F, Lawrence M, Timmreck C
Published: January, 2012
Publisher: Earth System Dynamics
DOI: 10.5194/esd-3-63-2012
Tags: Space Reflectors, Stratospheric Aerosols, Cloud Brightening, Climate Modelling
URL: http://www.earth-syst-dynam.net/3/63/2012/esd-3-63-2012.html
Abstract: In this study we compare the response of four state-of-the-art Earth system models to climate engineering under scenario G1 of two model intercomparison projects: GeoMIP (Geoengineering Model Intercomparison Project) and IMPLICC (EU project "Implications and risks of engineering solar radiation to limit climate change"). In G1, the radiative forcing from an instantaneous quadrupling of the CO2 concentration, starting from the preindustrial level, is balanced by a reduction of the solar constant. Model responses to the two counteracting forcings in G1 are compared to the preindustrial climate in terms of global means and regional patterns and their robustness. While the global mean surface air temperature in G1 remains almost unchanged compared to the control simulation, the meridional temperature gradient is reduced in all models. Another robust response is the global reduction of precipitation with strong effects in particular over North and South America and northern Eurasia. In comparison to the climate response to a quadrupling of CO2 alone, the temperature responses are small in experiment G1. Precipitation responses are, however, in many regions of comparable magnitude but globally of opposite sign.
Author(s): Kravitz B, Robock A, Boucher O, Schmidt H, Taylor KE, Stenchikov GL, Schulz M
Published: January, 2011
Publisher: Atmospheric Science Letters
DOI: 10.1002/asl.316
Tags: Stratospheric Aerosols, Climate Modelling
URL: http://onlinelibrary.wiley.com/doi/10.1002/asl.316/abstract
Abstract: To evaluate the effects of stratospheric geoengineering with sulphate aerosols, we propose standard forcing scenarios to be applied to multiple climate models to compare their results and determine the robustness of their responses. Thus far, different modeling groups have used different forcing scenarios for both global warming and geoengineering, complicating the comparison of results. We recommend four experiments to explore the extent to which geoengineering might offset climate change projected in some of the Climate Model Intercomparison Project 5 experiments. These experiments focus on stratospheric aerosols, but future experiments under this framework may focus on different means of geoengineering.
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