Asymmetric heatwave intensification under divergent climate change mitigation pathways amplifies urban–rural exposure disparities

Abstract

Unmitigated climate change poses threats to human and environmental well-being through increasingly intense and frequent heatwaves. However, the future impact of heatwaves on urban and rural populations remains uncertain. We project intensified heatwave characteristics and earlier onsets across numerous global regions using bias-corrected climate models. The projected impacts of limiting global warming to either regional-rivalry (SSP370) or fossil-fueled development (SSP585) pathways differ significantly, with SSP585 resulting in substantially more persistence and intensity than SSP370. Under SSP370, high heatwave frequency (HWF) correlates with low heatwave number (HWN) in most tropical regions, but the opposite is true in polar regions. Moreover, heatwave intensity is mostly governed by radiative and advective forcing, while persistence depends on large-scale flow stability. We further demonstrate that heatwave exposure varies considerably across different climate regions and population strata, with rural populations exhibiting exposure comparable to urban populations. Under SSP 370, the Tibetan region will witness rural population exposure to HWF totalling 15 million person-days, compared to 5 million person-days in urban population exposure. In East Asia, both the near and late-21st-century scenarios under SSP 370 show a dominant climate effect (at 90 %) governing the total changes to rural population exposure. In general, most regions are expected to witness the population effect dominance during SSP 370 in the mid-21st-century for rural populations, while the population effect dominance for urban populations varies by region. Our findings underscore the importance of developing customized adaptation plans to address the challenges of heatwaves in a changing climate. Show more