The growth of urban areas causes a range of stresses to the environment both within and beyond city limits. Through the conversion of land to built-up urban areas, biodiversity can be lost as habitats for species become fragmented (McKinney, 2008); local climates can change due to the creation of urban heat islands that modify temperatures (Oke, 1982); and natural resources and energy are consumed. The shift of dispersed human settlement to more dense urban concentrations of population and resources will also have environmental impacts that are not well understood (Miller and Small, 2003). The need for a solid scientific basis to better understand the linkages between urbanization and environment could not be more urgent. To do so requires a rigorous and comprehensive scientific underpinning for sustainable management and governance to address how urbanization impacts resource consumption and the environment within cities and its surroundings, particularly as they change over time. Whether urbanization as a process negatively impacts the environment, or whether cities can present possible solutions to environmental challenges is a puzzle.
Sustainable Development Goal (SDG) 11 identifies cities as critical and cross-cutting for addressing a range of environmental problems, including waste management, air and water quality, poverty and vulnerability to climate change impacts (UN, 2012). How cities can achieve these targets, however, particularly while experiencing growth and expansion into peri- and exurban areas, necessitates new streams of knowledge and information by which to guide sustainable policy solutions and track progress. The measurement challenge is even more compounded when taking into consideration what Brenner and Schmidt (2013) call the “continued lack of agreement on what needs to be measured, and at what scale” for urbanization. Therefore, the convergence of multiple disciplines and actors to establish a clear scientific link between urbanization and environmental systems (e.g., climate, air, and water) is critical to create relevant knowledge and information to guide global sustainability goals in which cities are anticipated to play a crucial role.
What knowledge is needed for urban sustainability? Is an ‘urban sustainability science’ required to understand the environmental impacts of urbanization, and the potential for cities to contribute to the global sustainability agenda? What information is needed to evaluate these challenges and potential? Can we develop typologies to characterize different modes and forms of urbanization that could lead to sustainable models of urban growth and development?