https://en.wikipedia.org/wiki/Stratospheric_aerosol_injection
>The ability of stratospheric aerosols to create a global dimming effect has made them a possible candidate for use in solar radiation management climate engineering projects[1] to limit the effect and impact of climate change due to rising levels of greenhouse gases.[2] Delivery of precursor sulfide gases such as sulfuric acid,[3] hydrogen sulfide (H
2S) or sulfur dioxide (SO
2) by artillery, aircraft[4] and balloons has been proposed.[5] Non-sulfide substances such as calcite have also been proposed given their benefits to the ozone layer.[6] It appears that this could counter most changes to temperature and precipitation, take effect rapidly, have low direct implementation costs, and be reversible in its direct climatic effects.[7] However, it would do so imperfectly and other effects are possible.[8]