As cities grow larger, they may also become less green

There is growing empirical evidence that cities share similar statistical patterns in terms of their social and economic characteristics. Many facets of urban life – ranging from personal income, innovation, crime, amenities, and infrastructure – have been found to follow non-linear, power-law scaling relationships with city size. Using Landsat and other satellite-derived data, we test whether urban green space exhibits scaling relationships on a global selection of 150 cities at global and individual city scales. We find that urban green space follows a pervasive sublinear scaling relationship with city size, both in terms of population and land area. Sublinear scaling indicates that green space declines in per-unit access as cities grow larger, which means that corresponding ecosystem services provided by green spaces will also likely decline. Without interventions to preserve and manage urban green space, future cities may become wealthier and more innovative as they grow, but will be relatively less green.