Urban thermal inequity: Advancing thermal justice transitions for vulnerable low-income populations

Urban overheating, driven by global climate change, rapid urbanisation and entrenched socio-economic inequality, has emerged as a defining challenge for cities in the twenty-first century. More than 1,000 cities worldwide are already affected, exposing approximately 1.7 billion urban residents to thermal conditions that exceed comfort and health thresholds. Heat risks are unevenly distributed within cities, with low-income populations experiencing disproportionately higher exposure, constrained adaptive capacity and greater economic burdens, reinforcing a self-perpetuating cycle of heat stress and vulnerability. Quantitative evidence reveals stark disparities in access to cooling, health outcomes, economic losses and learning capacity between affluent and disadvantaged urban communities. Here we argue that addressing urban thermal inequity requires a thermal justice transition that places equity at the centre of urban climate adaptation. We outline pathways for such a transition, including the targeted deployment of advanced cooling technologies in high-vulnerability areas, the development of metrics to quantify intra-urban exposure and adaptive capacity, the establishment of urban thermal safety nets and the mobilization of innovative financial instruments. Embedding scientific insights within inclusive urban policy and financing frameworks is essential to reduce overheating risks, protect vulnerable populations and enable climate-resilient, socially just urban futures.