Comparing a territorial-based and a consumption-based approach to assess the local and global environmental performance of cities

In the framework of pressing local and global environmental challenges it is essential to understand thatcities are complex systems dependent on and linked to the rest of the world through global supply chainsthat embody an array of environmental flows. Cities are thus a complex articulation that intertwine localand global challenges which rely at their extended hinterland for their resource use and pollutionemission. To assess the environmental sustainability of an urban area in a comprehensive manner, it isnot only necessary to measure its local and direct environmental performance but also to understand andtake into account its global and indirect environmental counterparts. This paper presents a comparativeanalysis of a territorial-based and a consumption-based approach to estimate both direct and embodiedresource use and pollution flows for the case of Brussels Capital Region (Belgium). The territorial-basedapproach is based on local energy, water and material consumption measured data as well as measureddata on waste generation and pollution emissions. The estimation of indirect resource use and pollutionemissions (or consumption-based approach) is based on the regional IO-tables of the city-region ofBrussels extended with multi-region input-output tables, taking into account the global flows of consumption.The comparison of these two approaches is particularly relevant in the case of cities that havelimited productive activities and limited or no extraction of materials as the impact on the hinterland isoften underestimated or neglected by local (environmental) policies which are only based on territorialbasedfigures. The results show that the indirect primary energy use, GHG emissions and material useestimated by the consumption-based approach is more than three times higher than local measuresindicate. The embodied water use, estimated via IOA, was over 40 times higher than the local waterconsumption. These results show that territorial-based approach using local data underestimate theresource needs and pollution emissions of a city and can therefore be insufficient or even be misguiding.By mapping the origin of embodied flows it is in fact possible to illustrate the open character of an urbaneconomy and its dependence on the global hinterland. Finally, this paper discusses the possibility andrelevance to combine these two approaches to create a hybrid framework that measures the full environmentalperformance of cities both accurately and comprehensively.SCOPUS: ar.j