Mapping global urban land for the 21st century with data-driven simulations and Shared Socioeconomic Pathways

Urban land expansion is one of the most visible, irreversible, and rapid types of land cover/land use change in contemporary human history, and is a key driver for many environmental and societal changes across scales. Yet spatial projections of how much and where it may occur are often limited to short-term futures and small geographic areas. Here we produce a first empirically-grounded set of global, spatial urban land projections over the 21st century. We use a data-science approach exploiting 15 diverse datasets, including a newly available 40-year global time series of fine-spatial-resolution remote sensing observations. We find the global total amount of urban land could increase by a factor of 1.8-5.9, and the per capita amount by a factor of 1.1-4.9, across different socioeconomic scenarios over the century. Though the fastest urban land expansion occurs in Africa and Asia, the developed world experiences a similarly large amount of new development. Here the authors develop a set of global, long-term, spatial projections of urban land expansion for understanding the planet's potential urban futures. The global total amount of urban land increases by a factor of 1.8-5.9 over the 21st century, and the developed world experiences as much new urban development as the developing world.