Urban resource use and environmental performance indicators. An application of decomposition analysis

Abstract

An evaluation of interlinkages and synergies among the different resources and performance patterns in the city of Rome (Italy) was accomplished by means of decomposition equations, in order to identify the major drivers of change in the investigated period as well as future low-resource scenarios. A half-a-century historical series (1962–2008) of energy and resource consumption in the city of Rome (Italy) was investigated in order to ascertain the links between resource use and complexity change. Environmental, material and energy inputs were firstly evaluated as actual energy and mass flows, then converted to emergy units to provide an assessment on a common ground. Results show that the sustainability of the urban system decreased steadily in the investigated period, as confirmed by both intensive and extensive parameters. The demand for abiotic matter, water, energy and emergy (environmental work) was accounted for over time and referred to the population (per-capita indicators) and current prices economic product generated by the city (GVA, Gross Value Added). Moreover, the effects associated with the emissions were evaluated, with a special focus on global warming and acidification potential. The changes in the urban metabolism occurred within the investigated period were analyzed considering the variation of different inputs necessary to drive the city (electricity, fuels, goods, machineries, etc.).Finally, a decomposition analysis was performed to identify the main causes and drivers associated with the changes in the city metabolism. Decomposition results show that the increased fraction of imports compared to local sources, of non-renewable resources 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 such unsustainability pattern and call for policies that focus on optimization of production and consumption patterns in times of unavoidable shrinking of resource basis.