The recently UN-adopted Sustainable Development Goals (SDGs) set out a globally unprecedented aspiration for cities. Among other aims (including inclusion, safety and resilience), SDG-11 aspires to ‘make cities and human settlements…sustainable…’ The implication, of course, is that cities are currently not very sustainable (see Figure 1). By many measures this is true; scholars have shown how many cities are exceeding the carrying and regenerative capacity of the planet. Seto et al. show that cities on average are using land less and less efficiently. While global material extraction has slowed relative to GDP, 80% of which is produced in cities, cement production is accelerating even faster than GDP. As an outcome, the IEA and UN-Habitat estimate that cities are responsible for 60-80% of energy use and 70% of greenhouse gas emissions, respectively.
Yet none of this is a fatal flaw inherent to the urban condition. Merely critiquing cities’ unsustainable throughputs is not enough, and mistaking them as parasites is even worse because it usually precipitates highly ineffective solutions (e.g., making cities less city-like). We must not retreat from the city. Cities contain within them the seeds for overcoming their negative externalities. Catalyzing such a transformation requires harnessing agglomeration advantages and tapping into the variety that compact, mixed-use cities offer.