Possibility of geoengineering stabilization of global temperature in the 21st century using the stratospheric aerosol and estimation of potential negative effects

The climate model of atmospheric and oceanic circulation is used to assess a potential of the geoengineering to stabilize the global temperature at the level of +2°C relative to the average for the 20th century. An anthropogenic forcing was set in accordance with the RCP8.5 scenario. The injection of H₂S into the stratosphere transformed afterwards into the sulfate aerosol starts when the temperature reaches a threshold of +2°C. The intensity of the injection is chosen so that the estimated global temperature remains close to the threshold. It is demonstrated that the stabilization of temperature by geoengineering is possible within +(2 ± 0.11)°C during the 21st century. The stabilization of temperature by the end of the 21st century needs the yearly injection of 4.5 Mt S in the form of H₂S. The specific efficiency of the method is about 0.09°C/Mt of aerosol. It was found that the stabilization of global temperature does not provide the stabilization of mean global precipitation. The maximum influence of aerosol is in the equatorial zone where its specific density in the atmosphere will reach 0.074 g/m² by the end of the 21st century. Carried out is a comparison of regional features of temperature and precipitation fields with and without geoengineering. It is shown that the geoengineering will decrease significantly the regional anomalies in the most part of regions and will not increase them in the rest part. Estimated is an effect of the rapid growth in global temperature at the dramatic cessation of geoengineering impacts. Considered is a variant of the gradual decrease in geoengineering intensity, when the negative effects will be smoothed.