Urban heat islands and nature-based solutions: insights into health impacts and urban planning determinants

The current and projected rapid urbanization rates underscore the critical role of cities and the urgent need to prioritize the development of healthy and sustainable urban environments. Rising temperatures, intensified by the urban heat island (UHI) effect, pose a significant health threat, particularly in European cities where they have been linked to a notable rise in mortality. This thesis investigates the health impacts of UHIs and examines the effectiveness of Nature-based Solutions (NbS) in mitigating these effects across European cities. It also explores which urban configurations types are most associated with UHI intensity, CO2 emissions, and health. The findings indicate that UHIs significantly contribute to mortality in European cities, and that increasing the urban tree cover density (TC) can mitigate some of these effects by cooling the urban environment. The evaluation of Barcelona’s “Green Corridors” plan as a case study revealed significant health benefits from increased green exposure, underscoring the multifaceted advantages of NbS and contributing to the debate on optimal heat mitigation strategies. Moreover, this thesis found that while present-compact cities have poorer environmental and health outcomes, they are more efficient in terms of CO2 emissions compared to their greener, less dense counterparts. To counteract these negative impacts, potential strategies include integrating NbS strategically, diversifying local destinations, promoting active transport, and redesigning urban areas to encourage walking and cycling while reducing motorized traffic. These measures should be customized to the specific contexts of each city, with a focus on collaboration among various stakeholders to effectively tackle challenges and promote healthier, more sustainable urban development.