Defining and measuring urban sustainability: a review of indicators

ContextThe sustainability of urban areas is essential to the sustainability of regions, nations, and the world as a whole. Urban sustainability indicators (USIs) can play an important role in advancing the science and practice of sustaining urban systems.ObjectivesWe review the key concepts of urban sustainability and commonly used indicators for gauging the state and progress of urban sustainability, and discuss how USIs can be further improved from a landscape ecology perspective.MethodsThis review is based primarily on peer-reviewed journal papers, as well as books, and documents published by international organizations, governmental agencies, and research institutions. We systematically examine what USIs actually measure and whether they are adequate for gauging urban sustainability, and then discuss major problems and challenges as well as ways forward in developing and applying USIs.ResultsNumerous USIs have been developed, including single composite indices and indicator sets. This paper focuses on three indicator sets and ten composite indices. Eight of them cover all the three dimensions of sustainability (environment, economy, and society), and five cover two of the three. Five of them measure strong sustainability, and eight only indicate weak sustainability.ConclusionsUrban sustainability indicators abound, and so do problems with them. These include technical issues of normalization, weighting, and aggregation (upscaling), as well as conceptual issues of indicator selection, boundary delineation, heterogeneity, scale, and strong versus weak sustainability. To overcome these problems, principles and methods in landscape ecology—particularly those of landscape metrics, spatial scaling, and landscape sustainability—have much to offer, and this represents a challenging and fruitful research direction for both landscape and urban scientists in the coming decades.