Abstract
<strong class="journal-contentHeaderColor">Abstract.</strong> Stratospheric aerosol intervention (SAI) geoengineering is a proposed scheme to counteract anthropogenic global warming, but the climate response to SAI, with great regional disparities, remains uncertain. In this study, we use Geoengineering Model Intercomparison Project G4 experiment simulations from six models that counteract anthropogenic forcing under mediumâlow emissions (Representative Concentration Pathway 4.5 â RCP4.5) by injecting a certain amount of SO<span class="inline-formula"><sub>2</sub></span> into the stratosphere every year to investigate the surface air temperature response to SAI geoengineering over China. We have found that SAI has led to surface cooling over China during the last 40Â years of injection simulation (2030â2069), which varies among models, regions, and seasons. Decreased tropospheric temperature and water vapor and increased stratospheric aerosols induce robust decreases in downward clear-sky longwave and shortwave radiation fluxes at the surface, respectively, dominating the temperature change over China. Changes in cloud effective forcing and surface albedo feedback also relate to the temperature response but with large spatial and seasonal variations. We find that the increased summer cloud cover and winter surface albedo lead to strong cooling, while the decreased summer cloud cover and winter surface albedo lead to weak cooling or even insignificant warming for the certain subregions and models. Our results suggest that cloud and land surface processes in models dominate the spatial pattern of SAI-induced surface air temperature change over China.
Highlights
The increasing anthropogenic greenhouse gas (GHG) concentrations since the industrial revolution have led to global warming
We use Geoengineering Model Intercomparison Project G4 experiment simulations from three models (HadGEM2ES, MIROC-ESM, and MIROC-ESM-CHEM) that offset anthropogenic forcing under medium-low emissions (RCP4.5) 15 by injecting a certain amount of SO2 into the stratosphere every year, to investigate the surface air temperature response to Stratospheric aerosol intervention (SAI) geoengineering over China
The results indicate that changes in SWC and SWSA mainly determine the spatial pattern of net surface SW changes caused by SAI
Summary
The increasing anthropogenic greenhouse gas (GHG) concentrations since the industrial revolution have led to global warming. Geoengineering, which aims to counteract global warming by 30 deliberately changing the climate system, is of great research interest. Geoengineering schemes are generally classified into two major types: carbon dioxide removal (CDR) geoengineering by reducing atmospheric carbon dioxide concentration, and solar radiation modification (SRM) geoengineering by increasing planetary albedo. The method of injecting sulfate aerosols or their precursors into the stratosphere, known as stratospheric aerosol intervention (SAI) geoengineering, is designed to cool the surface by using these aerosols to reflect and scatter solar radiation (Crutzen, 2006; Wigley, 2006). SAI geoengineering is considered the most promising SRM method due to its high effectiveness, affordability, and timeliness (Shepherd et al, 2009)
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