We ought to stop surface-level sulfur emissions, for human health and also because ship engines that produce sulfur also produce lots of other nasty shit.
Stratospheric sulfur is much more efficient, per kg, at reflecting sunlight, so we could replace the cooling effect of surface-level sulfur with stratospheric sulfur, and if we choose to, go even further to cool the planet more.
This will be the trigger that destroys us all, man thinking he has the knowledge to force climate change by manipulating atmospheric composition and then acting on it. Oh well.
Stratospheric sulfur is much more efficient, per kg, at reflecting sunlight, so we could replace the cooling effect of surface-level sulfur with stratospheric sulfur, and if we choose to, go even further to cool the planet more.