Urban metabolism

Urban metabolism is a model to facilitate the description and analysis of the flows of the materials and energy within cities, such as undertaken in a material flow analysis of a city. It provides researchers with a metaphorical framework to study the interactions of natural and human systems in specific regions. From the beginning, researchers have tweaked and altered the parameters of the urban metabolism model. C. Kennedy and fellow researchers have produced a clear definition in the 2007 paper The Changing Metabolism of Cities claiming that urban metabolism is "the sum total of the technical and socio-economic process that occur in cities, resulting in growth, production of energy and elimination of waste." With the growing concern of climate change and atmospheric degradation, the use of the urban metabolism model has become a key element in determining and maintaining levels of sustainability and health in cities around the world. Urban metabolism provides a unified or holistic viewpoint to encompass all of the activities of a city in a single model. With deep roots in sociology, Karl Marx and fellow researcher Friedrich Engels may have been the first to raise concerns around issues which we would now call urban metabolism. Marx and Engels concentrated on the social organization of the harvesting of the Earth's materials by "analysing the dynamic internal relationships between humans and nature." Marx used the metaphor of metabolism to refer to the actual metabolic interactions that take place through humans' exertion of physical labour to cultivate the Earth for sustenance and shelter. In short, Marx and Engels found that when humans exerted such physical labour they ultimately altered the biophysical processes as well. This acknowledgement of altering the biophysical landscape is the first stepping stone for the creation of urban metabolism within social geography. They also used metabolism to describe the material and energy exchange between nature and society in as a critique of industrialization (1883) which created an interdependent set of societal needs brought into play through the concrete organization of human labour.