Heat-related mortality mapping to inform heat adaptation measures

Abstract Climate change has increased summer air temperatures, leading to a significant rise in heat-related mortality. Since heat-related mortality varies spatially based on the distribution of landscape variables, population exposure, and vulnerability factors, it is crucial to identify areas with high heat-related mortality for prioritizing heat-adaptation measures. However, previous studies have been limited to quantify municipal or city level heat-related mortality and have not inform how landscape variables could reduce heat-related mortality spatially. We used a combined method of regional urban climate model and a relative risk function to quantify heat-related mortality in the Tokyo Metropolitan Area at a 1 km resolution. We found that densely populated areas around the central business district had high heat-related mortality (> 1.12 deaths/km 2 /2mon), and that heat-related mortality rate was negatively correlated with the fraction of water bodies, green areas, and road areas. Maximum greening (a 47% increase in green area fraction) could reduce total mortality by 9%, with a greater impact in high-risk areas. Our findings can support Tokyo Metropolitan’s 2030 greening goal is not enough to mitigate heat-mortality (implementing 1.1 km 2 of green area may reduce 0.3 mortalities during July and August) even if it is implemented in the priority areas. It underscores the importance of quantifying the effects of landscape variable-based solutions and prioritizing high-risk areas for future adaptation efforts.