Why does everyone think cities can save the planet?

This article identifies and explains an underlying transition in global urban policy and discourse from the city as a sustainability problem to the city as a sustainability solution. We argue that contemporary policy discourses of cities saving the planet should be understood in the context of three major historical developments which have their roots in the 1970s and which intensified throughout the 1990s. The first is sprawl: the urban sustainability policy agenda in the Global North has been in large part a reaction to several decades of urban expansion and car-based planning. The second is informal settlements: since the introduction of UN-HABITAT in 1978, an international policy agenda has formed around addressing the environmental deficits associated with processes of informal urbanisation above all in the Global South. And the third is climate change, as the overarching concern that connects urban-environmental problems and policies in the North and South. We then contextualise the articles in this special issue by outlining a new research agenda for decoding the notion that cities can save the planet, which emphasises the need for an historical, multi-spatial, political and representational analysis of urban sustainability thinking and policy.