Fig. 2: Initial conditions in the UK Earth System Model (UKESM) simulations conducted.

SO2 injection height (km) as a function of the quasi-biennial oscillation (QBO) index (m s−1) for the HIST (blue, historical climate) and SSP585 (red, high-end future climate) experiments. Dashed lines show the July-mean tropopause height at the eruption location (15.1°N,120.4°E) for the two climates. The QBO index was defined as the average zonal wind at 30 hPa between 15°S and 15°N. The injection height shown is the center height of the injection (see Methods section).