Quantifying the impacts of blue-green spaces on population exposure to heatwaves across climate zones
Yu Zhang, Rui Zhou, Xiangjun Lv, Qun Ma, Yalong Li, Chunlin Li, Xuening Fang, Jie Li, Zenan Zhang, Shubo Fang
Abstract
Abstract Context Against the backdrop of global climate change and enhanced human activities, heatwave issues occur frequently, and lead to increasing population heatwave exposure (PHE) risk. Although early studies have suggested that blue-green spaces (BGS) may mitigate PHE by regulating the surface thermal environment, few researches have investigated the comprehensive effect of various types of BGS on PHE from climate zone perspective, especially at the fine scale. Objectives This study attempted to investigate the comprehensive impacts of various BGS on PHE from the perspective of climate zones to provide more targeted decision support for PHE mitigation. Methods Taking China as the study area, this study quantified the relationship between various BGS and PHE across different climate zones, combined with gradient boosting regression tree (GBRT) model, shapley additive explanation (SHAP), and variance partitioning analysis (VPA). Results HAW (hot summer and warm winter) and HAC (hot summer and cold winter) climate zones had obviously higher probability of heatwaves than the other climate zones, and their PHE was very severe. BGS had a strong explanatory power for PHE variation in all climate zones. The joint explanatory power of various types of BGS for PHE was basically greater than their independent explanatory power. With the increase of latitude, the independent explanatory power of forest decreased, while that of grassland increased. The dominant factors influencing PHE varied with climate zones, but percentage of landscape, landscape shape and landscape connectivity of various BGS played more important roles in regulating PHE. Conclusions The effects of BGS landscape pattern on population heatwave exposure varied across different climate zones. Our findings can provide new and more targeted insights and decision-making guidance for government policymakers and planners in different climate zones, regarding he formulation of pattern optimization strategies and planning management policies of BGS, in order to effectively mitigate the population exposure to heatwaves.