a, Heat-related mortality as a percentage of total mortality during warm season (mortality fraction (%)) estimated in the 43 countries under the factual (all anthropogenic and natural forcings (shaded)) and counterfactual (natural forcings only (unshaded)) climate scenarios. b, Percentage of total deaths during warm season attributable to heat-related human-induced climate change, estimated as the difference in heat-related mortality in the factual compared to the counterfactual scenario, with the corresponding 95% CI. c, Proportion of heat-related mortality attributable to human-induced climate change estimated as the fraction of heat-related mortality in the factual scenario that results from the contribution of anthropogenic forcings.