The sulphates would wash out within a couple of years but again this "solution" does not address ocean acidity, or the potential acidity of the sulphate aerosols.
Secondly, by reflecting sunlight to cool the planet, such as with space-based mirrors, or by whitening clouds, or by spraying sulphate aerosols into the stratosphere to form a solar shield.
More importantly, there is evidence of an emerging pattern of climate response to forcings by greenhouse gases and sulphate aerosols in the observed climate record.
In a nutshell, this paper is important because it was the first study to investigate the effect of sulphate aerosols in a general circulation model of the climate system.