Measuring the biophysical dimension of urban sustainability

An ecological economics perspective on urban sustainability embraces a biophysical view which emphasizes the dependence of cities on vast quantities of natural capital from various sources and spatial scales, and the generation of urban wastes which impact the local, regional and global systems. In recent years, several sets of urban sustainability indicators and indices have been developed. However, only a few consider the complex multi-scale interactions between the urban activities and the environment. Furthermore, most existing indices use a relative evaluation approach instead of an absolute approach that is needed when dealing with ecological thresholds. The paper introduces a new urban biophysical sustainability index whose framework includes: the city environmental quality, use of natural resources, and GHG emissions. Each contains topics for assessment related to local, regional and global scales and associated indicators. Standard and optimum values were determined for each indicator and a formula is provided for grading each indicator measurement. The integration of those grades allows for generation of a compound score of each topic, category, spatial scale and the entire urban biophysical sustainability performance. It then demonstrates the index in three major Israeli cities.