The front matter to “Cities of Hydrocarbon,” the third of three parts of Earthopolis: A Biography of Our Urban Planet pivots from an interview with a rickshaw driver in Delhi about the effects of the city’s smoky air to announce the major themes of modern global urban history. These include the acceleration of growth due to the powerful new way of harnessing geo-solar energy, the growing turbulence of political life due to the rise of revolutionary movements in cities and their enlarged hinterlands, the emergence of a truly planetary city-dominated human habitat, as well as a vastly expanded realm of human impact. It finishes by reminding readers of the growing consequences we face as an urban species in command of the planet, in the form of increased pandemic disease and atmospheric heating.