Abstract

Stratospheric aerosol intervention (SAI) geoengineering is a rapid, effective, and promising means 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 three models (HadGEM2-ES, MIROC-ESM, and MIROC-ESM-CHEM) that offset anthropogenic forcing under medium-low emissions (RCP4.5) by injecting a certain amount of SO2 into the stratosphere every year, to investigate the surface air temperature response to SAI geoengineering over China. It has been shown that the SAI leads to surface cooling over China over the last 40 years of injection simulation (2030–2069), which varies among models, regions and seasons. The spatial pattern of SAI-induced temperature changes over China is mainly due to net surface shortwave radiation changes. We find that changes in solar radiation modification strength, surface albedo, atmospheric water vapor and cloudiness affect surface shortwave radiation. In summer, the increased cloud cover in some regions reduces net surface shortwave radiation, causing strong surface cooling. In winter, both the strong cooling in all three models and the abnormal warming in MIROC-ESM are related to surface albedo changes. Our results suggest that cloud and land surface processes in models may dominate the spatial pattern of SAI-induced surface air temperature changes 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

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Summary

Introduction

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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