Heat Wave with High Impact on Human Health under Global Warming

Heat wave (HW) is one of extreme meteorological disasters in summer, which brings sever impact on human health and labour loss. Because climate change has become the biggest global health threat of the 21^st century, future projection of global HW is unprecedented necessary for disaster prevention and mitigation. This study projects HW events with high impact on human health based on ScenarioMIP experiments from the Coupled Model Intercomparison Project Phase 6 (CMIP6). In observation, the accumulated days of summer HW events with high impact on human health mainly occur in extratropical regions. The maximum HW days appear along 30°S and 30°N, respectively. The evaluation of CMIP6 models on simulating HW with high impact on human health shows that the spatial and temporal distribution of HW days are roughly reproduced, which proves that these models could be used to project this type of HW in the future. In order to describe the relationship between HW days in tropical and extropical regions, the ratios of accumulated days of HW averaged over tropical regions against extratropical regions in Northern/ Southern Hemisphere are purposely defined. In CMIP6 projections, these ratios turn from less than 1 in present to greater than 1 in late 21^st century, which indicates that the HW in tropical regions will remarkably increase in the future. Further analysis shows that this significant change of HW days with high impact on human health should be ascribed to the change of temperature variability. Recognizing the characteristics and understanding the mechanism of HW with high impact on human health under global warming is crucial in the mitigation of risks and in adaptations to climate change.