Take refuge! Using mobile phone data to evaluate Blue-Green Infrastructure's attractiveness as Heat Retreat Locations

As anthropogenic impacts on the global climate intensify, heatwaves are becoming increasingly severe, frequent, and prolonged worldwide. In parallel, the rapid pace of urbanization underscores the urgent need to understand the impacts of extreme temperatures on the well-being of urban populations. In this study we leverage mobility information from mobile phone data to analyze occupancy patterns in Zurich’s leisure facilities during hot summer and heatwave days. Our goal is to characterize city dwellers’ heat alleviation strategies towards active and passive cooling facilities. Additionally, we identify key infrastructural features of open public spaces contributing to thermal comfort and areas’ attractiveness. Our findings suggest that bathing sites serve as primary heat retreat destinations in Zurich, where major increases in areas’ attractiveness are observed during the hottest days of the year. Moreover, while local conveniences, transport connectivity and cultural amenities influence baseline open public spaces’ attractiveness, seasonal variations are more strongly governed by temperature regulation features, such as waterfront extent, vegetation canopy, and the presence of artificial water structures. Our study highlights water as an essential component of cities’ adaptation to heat, emphasizing its importance in enhancing urban resilience. Mobility data offers valuable insights into collective behavioral responses to climate constraints, supporting data-driven strategies to identify, enhance, and promote effective heat retreat locations within urban environments.