The paper starts from the premise that it is vitally important to recognize that the rapid rate of planetary urbanization is the main driver of environmental change. Indeed, the ‘sustainability’ of contemporary urban life (understood as the expanded reproduction of its socio-physical form and functions) is responsible for 80% of the world’s use of resources and most of the world’s waste. We wish to highlight how these urban origins are routinely ignored in urban theory and practice, and how feeble techno-managerial attempts to produce more ‘sustainable’ forms of urban living are actually heightening the combined and uneven socio-ecological apocalypse that marks the contemporary dynamics of planetary urbanization. This paper is, therefore, not so much concerned with the question of nature IN the city, as it is with the urbanization OF nature, understood as the process through which all forms of nature are socially mobilized, economically incorporated and physically metabolized/transformed in order to support the urbanization process. First, we shall chart the strange history of how the relationship between cities and environments has been scripted and imagined over the last century or so. Second, we shall suggest how the environmental question entered urban theory and practice in the late 20th century. And, finally, we shall explore how and why, despite our growing understanding of the relationship between environmental change and urbanization and a consensual focus on the need for ‘sustainable’ urban development, the environmental conundrum and the pervasive problems it engenders do not show any sign of abating. We shall conclude by briefly charting some of the key intellectual and practical challenges ahead.