Modeling of solar radiation management: a comparison of simulations using reduced solar constant and stratospheric sulphate aerosols

Kalidindi, Sirisha and Bala, Govindasamy and Modak, Angshuman and Caldeira, Ken (2015) Modeling of solar radiation management: a comparison of simulations using reduced solar constant and stratospheric sulphate aerosols. In: CLIMATE DYNAMICS, 44 (9-10). pp. 2909-2925.

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Abstract

The climatic effects of Solar Radiation Management (SRM) geoengineering have been often modeled by simply reducing the solar constant. This is most likely valid only for space sunshades and not for atmosphere and surface based SRM methods. In this study, a global climate model is used to evaluate the differences in the climate response to SRM by uniform solar constant reduction and stratospheric aerosols. Our analysis shows that when global mean warming from a doubling of CO2 is nearly cancelled by both these methods, they are similar when important surface and tropospheric climate variables are considered. However, a difference of 1 K in the global mean stratospheric (61-9.8 hPa) temperature is simulated between the two SRM methods. Further, while the global mean surface diffuse radiation increases by similar to 23 % and direct radiation decreases by about 9 % in the case of sulphate aerosol SRM method, both direct and diffuse radiation decrease by similar fractional amounts (similar to 1.0 %) when solar constant is reduced. When CO2 fertilization effects from elevated CO2 concentration levels are removed, the contribution from shaded leaves to gross primary productivity (GPP) increases by 1.8 % in aerosol SRM because of increased diffuse light. However, this increase is almost offset by a 15.2 % decline in sunlit contribution due to reduced direct light. Overall both the SRM simulations show similar decrease in GPP (similar to 8 %) and net primary productivity (similar to 3 %). Based on our results we conclude that the climate states produced by a reduction in solar constant and addition of aerosols into the stratosphere can be considered almost similar except for two important aspects: stratospheric temperature change and the consequent implications for the dynamics and the chemistry of the stratosphere and the partitioning of direct versus diffuse radiation reaching the surface. Further, the likely dependence of global hydrological cycle response on aerosol particle size and the latitudinal and height distribution of aerosols is discussed.

Item Type:	Journal Article
Publication:	CLIMATE DYNAMICS
Publisher:	SPRINGER
Additional Information:	Copy right for this article belongs to the SPRINGER, 233 SPRING ST, NEW YORK, NY 10013 USA
Keywords:	CLIMATE-CHANGE; GEOENGINEERING SCHEMES; IRRADIANCE REDUCTION; HYDROLOGICAL CYCLE; IMPACT; PINATUBO; BALANCE; VEGETATION; ERUPTION; HISTORY
Department/Centre:	Division of Mechanical Sciences > Divecha Centre for Climate Change Division of Mechanical Sciences > Centre for Atmospheric & Oceanic Sciences
Date Deposited:	28 Apr 2015 07:13
Last Modified:	28 Apr 2015 07:13
URI:	http://eprints.iisc.ac.in/id/eprint/51415

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