Urban heat island adaptation and mitigation in practice: lessons from policy implementation in five cities

The urban heat island (UHI) phenomenon presents pressing challenges for urban sustainability, intersecting urban planning, building design, public health and climate adaptation and mitigation policy. While UHI science has advanced, its knowledge and practice translation into real-life practice remains limited. This paper investigates the processes of how UHI knowledge can support the transition from diagnosing urban climate risks to shaping more thermally resilient cities. It begins by outlining the interdisciplinary significance of urban heat governance and highlights the persistent gap between scientific understanding and actionable outcomes by drawing from five global contexts-Japan, Germany, the United States, Hong Kong and Singapore. The paper explores how scientific insights are integrated into planning instruments, design regulations and environmental performance frameworks. Using an implementation science perspective, the paper examines four key themes: (i) barriers and enablers of science-policy integration, (ii) knowledge co-production, (iii) boundary objects and interfaces, and (iv) policy diffusion across cities. Findings emphasize the importance of institutional coordination, iterative co-production and simple and user-friendly tools for planners. The paper concludes by proposing a forward-looking research agenda focused on integrated modelling, climate-resilient design and community-driven approaches, contributing to a growing discourse on reorienting urban climatology towards practice for more equitable and sustainable cities.This article is part of the theme issue 'Urban heat spreading above and below ground'.