Motivation and background.- GLOMAP-mode overview.- The role of time-averaged volcanic sulphur emissions in the pre-industrial Era.- Impact of the 1783-1784AD Laki eruption on global aerosol formation processes and cloud condensation nuclei.- Impact of the 1783-1784 AD Laki eruption on cloud drop number concentrations and the first aerosol indirect effect.- What if a Laki-style eruption were to happen tomorrow?.