Global socioeconomic exposure of heat extremes under climate change

Growing evidence indicates that the risk of heat extremes will increase as climate change progresses and create a significant threat to public health and the economy. Socioeconomic exposure is the key component for assessing the risk of such events. To quantify socioeconomic exposure to heat extremes for 2016–2035 and 2046–2065, we use the projections of five global climate models forced by using three representative concentration pathways (RCPs) and projections of population and gross domestic product (GDP), and we take into account the geographic change in the distribution in shared socioeconomic pathways (SSPs). The exposure of the global population for 2046–2065 is the greatest under the RCP8.5-SSP3 scenario, up to 1037(±164) × 109 person-days, and the global GDP exposure for 2046–2065 is greatest under the RCP2.6-SSP1 scenario, up to 18(±2) × 1015 dollar-days. Asia has the highest exposure among all continents for both population and GDP, accounting for over half of the global exposure. Africa has the largest increase in exposure, with the annual population and GDP exposures increasing by over 9- and 29-fold, respectively, compared with the base period (1986–2005). The effect of climate makes the dominant contribution (47%–53%) globally for the change in population exposure. Changes in the geographic distribution of GDP cause nearly 50% of the total change in GDP exposure for 2016–2035. Mitigating emissions of greenhouse gases, either at the level of the RCP2.6 scenario or at a more ambitious target, is essential for reducing socioeconomic exposure to heat extremes. In addition, designing and implementing effective measures of adaptation are urgently needed in Asia and Africa to aid socioeconomic systems suffering from heat extremes due to climate change.