Increasing population exposure to future heatwaves influenced by land-atmosphere interactions

Heatwaves have significant effects on ecosystems and human populations. Human habitability is impacted severely as human exposure to heatwaves is projected to increase, in which land-atmosphere interactions make a vital contributing factor. Future risk of heatwaves is substantial and imminent worldwide. Increasing heatwave trends have demonstrated the need of effective measures for adaptation to persistent hot temperature extremes and ambitious mitigation to limit further increases in heatwave severity.

This study examines whether the projected intensification of land-atmosphere interactions contributes to projected increases in heatwave events and what this may mean for future population exposure to heatwaves. With the intensification of land-atmosphere interactions, heatwaves are found to increase by up to 40 days, intensify by up to 4.5 °C averagely in global land regions, with increasing frequency of 33% over most mid-latitude land regions by 2070–2100 under the RCP8.5 high emissions scenario. Furthermore, dry soil moisture conditions have a significant role in projected increases of multiple heatwave characteristics regionally compared with the global land area. Land-atmosphere interactions contribute as much as 35.7% to an average of 39.3% more of today’s global population exposure to heatwaves. Our results highlight contributions from land-atmosphere interactions on both heatwaves and their impacts on human population.