Designing policy for Earth's urban future

Although the importance of cities has been recognized through international agreements such as the 2030 Agenda for Sustainable Development, the worldwide impact of urban growth upon all Earth systems is not well recognized by the international policy community. Collectively, cities drive global change at an unprecedented scale, transforming land cover, hydrological systems, climate, biogeochemistry, and habitats. Cities are the nucleus from which humanities’ impact on all Earth systems can be observed. One would thus expect urban dynamics and impacts to be at the top of global governance agendas. We argue that one key factor that contributes to this lack of recognition is the absence of a global-level urban science advisory system, which could support the United Nations (UN) and regional multilateral groups with international policy-making. Achieving such a system requires the acknowledgment of three things: aggregate or cumulative impacts of urbanization globally, urban blind spots in present international policy-making, and diversity and potential contributions of urban science.