Simulation of the effect of stratospheric aerosol dimming parameters on the efficiency of offsetting global greenhouse climate warming

We considered different properties of stratospheric sulfate aerosols and their size distributions and estimated how efficient they are at compensating for the changes in radiative fluxes at different atmospheric levels and deviation of air temperature during greenhouse warming and upon aerosol dimming. A two-dimensional zonally averaged model of the annually average radiative and thermal regime of the troposphere and stratosphere (the Energy Balance Radiative Convective Model, EBRCM) is used for this. This model allows for assessing the direct effects of changes in many parameters of atmospheric aerosols and the underlying surface, as well as characteristics of aerosol screens. We estimate the sulfate aerosol optical depths and masses for offsetting the annually and zonally averaged increases in the near-ground air temperature, caused by increases in the greenhouse gas content, according to measurements and the IPCC A2 scenario for 1970–2050. No offset is indicated if aerosol screens are emplaced in the polar zones (poleward of 70° N–70° S), and a screen emplaced in just one hemisphere is shown to be incapable of producing total offsetting of global warming.