Fig. 3: Relationships between global warming and population exposed outside the temperature niche for different fixed population distributions.

a, Population (%) exposed to unprecedented heat (MAT ≥29 °C) for the different population distributions: 6.9 billion (blue; n = 65, coefficient = 11.9 % °C⁻¹, r² = 0.83); 9.5 billion (green; n = 65, coefficient = 13.8 % °C⁻¹, r² = 0.83); and 11.1 billion (red; n = 65, coefficient = 17.5 % °C⁻¹, r² = 0.83). b, Population (%) exposed outside the temperature niche due to temperature change only (purple; n = 65, coefficient = 11.8 % °C⁻¹, forcing intercept at 1960–1990 global warming of 0.3 °C), and due to the combined effects of temperature change and demographic change, for different fixed population distributions: 6.9 billion in 2010 (blue; n = 65, coefficient = 11.0 % °C⁻¹, r² = 0.83); 9.5 billion following SSP2 in 2070 (green; n = 65, coefficient = 9.5 % °C⁻¹, r² = 0.84); and 11.1 billion following SSP3 in 2070 (red; n = 65, coefficient = 9.1 % °C⁻¹, r² = 0.84). The shaded regions correspond to 95% two-sided confidence intervals of the estimated regression coefficients.