ABSTRACT
As discussed in Chapter 1, over half of the world’s population now lives in cities and this fraction is expected to rise in the coming decades. The trend raises questions about the sustainability of urban settlements and the extent to which they will be able to ‘meet the needs of the present without compromising the ability of future generations to meet their own needs’ (WCED 1987). To address this challenge, urban governments are looking for ways to measure the state of their city and to evaluate progress against desired targets, such as reducing the environmental impact of an urban area.
