Codes of the essay

Amid worsening climate change, the health risks of heatwaves are increasing. Urban green spaces have proven to lower temperatures and mitigate these risks. This study estimates the mortality burdens of ischemic heart disease, stroke, and chronic obstructive pulmonary disease (COPD) attributable to heatwaves in 232 cities in China, using five-year age group data and fine resolution data of urban green space. Based on current greenness levels and a counterfactual scenario, the study compares historical (2001-2021) and future (2022-2035) periods under three climate scenarios. From 2001 to 2021, heatwaves caused an average of 486,340 (95%CI 347,703-617,075), 835,019(95%CI 655,732-957,913), and 2,449,840 (95%CI 1,827,531-2,955,119) deaths from the three diseases, respectively. Increasing green coverage by 18.33%(SD 6.43, range 0.75%-29.17%) could reduce urban temperatures by 0.20°C (SD 0.16, range 0.01-1.12), potentially preventing 19,511(95%CI 16,219-20,554), 27,209(95%CI 27,060-27,631), and 75,809 (95%CI 71,995-77,270) heatwave-related deaths. The results of this study show the impact of heatwaves on mortality rates for specific diseases and highlight the health benefits of increasing tree coverage for urban residents.