Extended Data Fig. 1: The effect of aerosol forcing uncertainty on future temperature projections under high ambition scenarios.

a) The 90% confidence range in global mean surface temperature change depicted in (b) as a function of ERF_aer uncertainty and mean ERF_aer sampled as described in the methods. b) The global surface mean temperature change relative to 1850 under SSP1-1.9 and sampled from an ensemble of simulations²⁴ consistent with historical temperatures (1850–2019), ocean heat content change (1971–2018) and CO₂ concentration (1750–2014) assuming three different reduced uncertainty ERF_aer estimates: weak (mauve); medium (orange) and strong (blue). The 90% confidence range for each subset at the end of the century is indicated to the right of the axis. Observed surface temperatures averaged across four available datasets are shown in black. The underlying heatmap shows the average ERF_aer of the ensemble members that produce a given temperature change each year where the ensemble density is greater than 10%. The colormap is centred around the median ERF_aer in the ensemble and ranges between the 10th-90th percentiles.