Fig. 4: Zonally averaged ozone column changes and related uncertainties for injections of 5 Mt of material per year.

Injections of SO₂ are shown in red, alumina (r = 240 nm) in blue and calcite (r = 240 nm) in green. Thick lines: most reasonable uptake coefficients (Section SAI microphysics and heterogeneous chemistry). Shaded areas show corresponding uncertainties (see Methods): in blue for alumina assuming full coverage by H₂SO₄ − H₂O for the upper and non-dissociative HCl uptake without H₂SO₄/HNO₃ co-adsorption for the lower limit³³; in green for calcite assuming γ_HCl = 10⁻³ and \({\gamma }_{{{{{\rm{HNO}}}}}_{3}}=1{0}^{-5}\) for the upper and γ_HCl = 10⁻⁵ and \({\gamma }_{{{{{\rm{HNO}}}}}_{3}}=1{0}^{-3}\) for the lower limit; in red for SO₂ assuming heterogeneous reaction rate coefficients to be higher or lower than recommended values³⁶ by a factor of 2 for Reaction (1) and by a factor of 5 for the heterogeneous chlorine and bromine activation reactions. a For 2020 and (b) for 2090 boundary conditions. For underlying SADs see Supplementary Fig. 7.