Codes of the essay

Heatwaves, intensified by climate change and urban heat islands, pose a severe threat to global public health, particularly in densely populated cities. While the cooling effect of urban green spaces is recognized, quantifying their impact on heatwave-related mortality spatially explicitly at the city scale for specific age groups remains a critical challenge. This study presents a high-resolution assessment of how increased residential green coverage may help mitigate heatwave-related mortality from ischemic heart disease, stroke, and COPD across 232 Chinese cities from 2001 to 2035. We found that during 2001–2021, heatwaves were attributable to annual averages of 23,159 ischemic heart disease deaths, 39,763 stroke deaths, and 116,659 COPD deaths. Uniquely, our analysis projects that increasing urban green coverage by an average of 18.33% could reduce ambient temperatures by 0.20°C and potentially prevent approximately 19,764-26,360 annual deaths under future climate scenarios. This research provides the first large-scale, spatially explicit evidence for mainland China, highlighting the disproportionate protection for vulnerable age groups—specifically the elderly for cardiovascular diseases and a younger cohort for COPD. The findings offer actionable scientific evidence for urban planning policies aimed at climate adaptation, suggesting that strategic greening is a promising, nature-based solution that may help reduce the estimated health burden of heatwaves.