Fig. 5: Projected exposure to uncompensable heat stress (G^day > 0 W m⁻²) for subpopulations engaged in outdoor water collection and farming.

Land area (a, c) and population (b, d) at risk, shown separately for those engaged in water collection (a, b) and farming (c, d) under sun, shade, and dark scenarios. Percentage estimates are restricted to the specified subpopulation: for example, in a, the “Percent area (%)” refers to the percent of the land area currently inhabited by people who must walk outside to collect water that is projected to experience uncompensable heat stress. Spatially resolved water access data and agricultural population data are described in Supplementary Method 2 and presented in Supplementary Fig. 2. Lines denote the ensemble median, and the shaded areas indicate the 25th–75th percentile interval. In the shade scenario, the orange line indicates the average radiation exposure under shade and the error bars indicate the uncertainty (±50% of R_in; Eq. (3) for the shade scenario) under various shading objects. Uncompensable heat stress impacts are determined using the average data of a 10-year period matching each global warming amount most closely (tolerance of ±0.05 °C). There are only ten models that provide 10-year data corresponding to the warming amount of 4 °C, which contributes to a slight drop in the ensemble median at 4 °C.