The Introduction to Earthopolis: A Biography of Our Urban Planet outlines large themes in the 6,000-year story of how cities gave humans the power to dominate Earth. Our Urban Planet is at once a plural and a singular phenomenon. Its diversity reflects the many birthplaces and birthdates of cities on six continents over six millennia, yet it has become a connected city-enabled habitat of a single species on a single planet. Cities – compact built spaces that rely on many other, dispersed ones – allowed us to harvest enough energy from the Sun and Earth to create the political communities, institutions, wealth, and ideas we needed to act on a global scale, to build an Earth-encrusting habitat, to impact all other parts of our planet’s biosphere, and to face the consequences. The life of Earthopolis exists in space and time. As our urban harvests of natural energy transformed throughout global urban history, from river valleys to the world ocean, and then to hydrocarbon, the geographic extent of our Urban Planet’s four defining realms – of human action, habitat, impact, and consequence – expanded and retreated across Earth. Now our Urban Planet puts us in perilous command of our host planet’s entire halo of life.

This chapter focuses on intensifying urbanization as a global phenomenon. Each year, the equivalent of two cities the size of Tokyo are built; one in six urban dwellers live in slums; and we are heading towards that black figure of 2°C global warming (the subject of the next chapter). The twenty-first century has been already called the ‘Urban Century’, supposedly leaving behind the Century of Nation-States (the twentieth century) and the Century of Empires (the nineteenth century) as prior dominant forms. While it is certainly true that urbanization has become one of the dominant global trends, this prognosis is hyperbolic, missing the tensions between different levels and forms of governance. Cities across the world are crossed by global processes of ecological pressure, economic fragility, political contestation, and cultural questioning. All of this means that the current approach to ‘global cities’ is reductive and skewed. Here, we confront a shibboleth in scholarly writing—not only has the urbanization of the world been a long-term if massively accelerating process, but it should also be said that cities have long been the locus of globalization processes.