Exploring the Dependence of Urban Systems on the Environment

Abstract

A half-a-century historical series (1962-2008) of energy and resource consumption in the city of Rome (Italy) is investigated in order to ascertain the links between resource use and complexity change. Environmental, material, and energy inputs evaluated as actual energy and mass flows, are converted into impact indicators (local and cumulative abiotic material requirement, water demand, energy demand, airborne emissions and finally total emergy use). All calculated indicators are interpreted within a comprehensive framework SUMMA (SUstainability Multimethod Multiscale Assessment) capable to take into account different dimensions of the investigated systems. Based on the same set of input data, SUMMA generates consistent performance indicators, in which the results of each method are set up against each other and contribute to providing a comprehensive picture on which conclusions can be drawn. An evaluation of inter-linkages and synergies among the different resources and performance patterns in the city of Rome is also presented by decomposition equations to identify the major drivers of change within the period investigated as well as the future low-resource scenarios. Results show that sustainability of the urban system decreased steadily during the investigated period, as confirmed by intensive and extensive parameters. The increased fraction of imports compared to local sources, of non-renewables compared to renewables, as well as of population and per capita income not accompanied by sufficient increase of energy and material efficiency are the major drivers of the pattern of unsustainability and call for policies that focus on optimisation of the patterns of production and consumption in times of unavoidable shrinking of the resource base.