This chapter examines the global urban issues raised by an accelerated and intensified process of overheating. Under conditions of climate change and continued urbanisation, one of the critical challenges of the twenty-first century will be to manage thermal metabolism in ways that sustain urban life during extreme heat events. International non-governmental organisations, climate experts and urban social movements are starting to examine how the new thermal landscape will reshape the future conduct and experience of everyday urban life. First, ‘Sustainable Energy for All’, in their 2018 report “Chilling Prospects”, demonstrates the huge scale of the problem of extreme heat and the complex material and social transition required to provide sustainable cooling for all. Second, the ‘Union of Concerned Scientists’ in 2019 published a report titled “Killer Heat in the United States” that provides an analysis of the mid- and late century implications of continued climate change on the frequency, duration and location of heat extremes.