Sabine Barles

Urban Metabolism of Paris and its Region

The article presents the results of a research project aimed at (1) examining the feasibility of material flow analysis (MFA) on a regional and urban scale in France, (2) selecting the most appropriate method, (3) identifying the available data, and (4) calculating the material balance for a specific case. Using the Eurostat method, the study was conducted for the year 2003 and for three regional levels: Paris, Paris and its suburbs, and the entire region. Applying the method on a local scale required two local indicators to be defined in order to take into account the impact of exported wastes on MFA: LEPO, local and exported flows to nature, and DMC, a modified domestic material consumption (DMC) that excludes exported wastes (and imported ones if necessary). As the region extracts, produces, and transforms less material than the country as a whole, its direct material input (DMI) is lower than the national DMI. In all the areas, LEPO exceeds 50% of DMI; in contrast, recycling is very low. The multiscale approach reveals that urban metabolism is strongly impacted by density and the distribution of activities: the dense city center (Paris) exports all of its wastes to the other parts of the region and concentrates food consumption, whereas the agricultural and urban sprawl area consumes high levels of construction materials and fuel. This supports the use of MFA on an urban and regional scale as a basis for material flow management and dematerialization strategies and clearly reveals the important interactions between urban and regional planning and development, and material flows.

Society, energy and materials: the contribution of urban metabolism studies to sustainable urban development issues

Urban areas, in particular cities, are significant consumers of materials and energy, either directly on their land areas or indirectly through the materials, goods and services they import or export; there are upstream and downstream consequences of the removal of resources and the discharge of waste materials (to the atmosphere, water and soils), with multiple impacts on the biosphere. The processes involved need to be better characterised to reduce these environmental pressures. This is a sustainable development issue and it is a major goal of a field ecology which has been described as urban, industrial or sometimes territorial. This paper reviews the specific origins and findings of studies on urban metabolism. It describes the analysis tools used, including material and substance flows, energy balances, ecological, water and, more generally, environmental footprints. Finally, recent findings and areas for future research in the dematerialisation of urban societies are summarised.

Energy and material flows of megacities

Significance Our quantification of energy and material flows for the world’s 27 megacities is a major undertaking, not previously achieved. The sheer magnitude of these flows (e.g., 9% of global electricity, 10% of gasoline; 13% of solid waste) shows the importance of megacities in addressing global environmental challenges. In aggregate the resource flows through megacities are consistent with scaling laws for cities. Statistical relations are established for electricity use, heating/industrial fuels, ground transportation, water consumption, waste generation, and steel production in terms of heating-degree days, urban form, economic activity, and population growth. Analysis at the microscale shows that electricity use is strongly correlated with building floor area, explaining the macroscale correlation between per capita electricity use and urbanized area per capita. Understanding the drivers of energy and material flows of cities is important for addressing global environmental challenges. Accessing, sharing, and managing energy and material resources is particularly critical for megacities, which face enormous social stresses because of their sheer size and complexity. Here we quantify the energy and material flows through the world’s 27 megacities with populations greater than 10 million people as of 2010. Collectively the resource flows through megacities are largely consistent with scaling laws established in the emerging science of cities. Correlations are established for electricity consumption, heating and industrial fuel use, ground transportation energy use, water consumption, waste generation, and steel production in terms of heating-degree-days, urban form, economic activity, and population growth. The results help identify megacities exhibiting high and low levels of consumption and those making efficient use of resources. The correlation between per capita electricity use and urbanized area per capita is shown to be a consequence of gross building floor area per capita, which is found to increase for lower-density cities. Many of the megacities are growing rapidly in population but are growing even faster in terms of gross domestic product (GDP) and energy use. In the decade from 2001–2011, electricity use and ground transportation fuel use in megacities grew at approximately half the rate of GDP growth.

Grain, meat and vegetables to feed Paris: where did and do they come from? Localising Paris food supply areas from the eighteenth to the twenty-first century

The food supply to a large metropolis such as Paris involves huge fluxes of goods, which considerably impact the surrounding rural territories. Here, we present an attempt to localise Paris food supply areas, over a period of two centuries (1786, 1886, 2006), based on the analysis of data from transportation and production statistics for cereals, animal products, and fruits and vegetables, all three categories being expressed in terms of their nitrogen (i.e. protein) content. The results show contrasting trends for the three types of agricultural products. As for cereals, the Paris supply area remained for the most part restricted to the central area of the Paris basin, a region which gradually became specialised in intensive cereal production. Conversely, as animal farming had been progressively excluded from this area, regions located west and north of Paris (Brittany, Normandy, Nord-Pas-de-Calais) gradually dominated the supply of animal products to the metropolis. In addition, imported feed from South America today contributes as much as one-third of the total ration of feed in the livestock raised in these regions. For fruits and vegetables, about one-half of the Paris supply currently comes from long-distance imports, the other half coming from areas less than 200 km from Paris. As a whole, the Paris food supply area, although it has obviously enlarged in recent periods, is still anchored to an unexpected extent (about 50%) in its traditional nearby hinterland roughly coinciding with the Seine watershed, and in the regions specialised in animal farming located west and north. On the other hand, the agricultural system of the main food supply areas has considerably opened to global markets.

History of the urban environmental imprint: introduction to a multidisciplinary approach to the long-term relationships between Western cities and their hinterland

This paper introduces a series of 11 studies on the relationships between large Western cities (Paris, London, Brussels, Vienna, Barcelona, Athens, New York, Providence) and their surrounding territories over a long historical time period. The concept of hinterland is introduced to designate a rural territory structured by its function of supplying the city with food, fuel, water and other material. The papers question the usefulness of this concept in the current globalized world, where cities are often considered as simple nodes of a network of worldwide trade exchanges, but where new citizen aspirations for reconnecting urban and rural territories are emerging.

The Nitrogen Question: Urbanization, Industrialization, and River Quality in Paris, 1830—1939

This article analyzes the ways in which hygienists, scientists, and officials in nineteenth-century Paris came to understand nitrogen as an asset, not just a problem. In so doing, they became convinced of the necessity to give back to the land what the city had taken. This involved identifying nitrogen sources and flows in the city, using urban and industrial wastes as nitrogen fertilizers for agriculture, and developing the organic and mineral fertilizer industry in Paris. The solutions they proposed extended far beyond the river itself to include the organization of the city of Paris and its region. This interest in nitrogen led to the first calculations in France of nitrogen balance and flow and stimulated efforts to reduce nitrogen loss for hygienic, environmental, and agricultural reasons. The final part of the essay seeks to explain why this intense activity failed to survive the First World War.

History of Waste Management and the Social and Cultural Representations of Waste

The history of waste mirrors that of the societies that produced it, and their relationship with the environment and the resources they mobilized. Until the industrial revolution, the management of urban excreta was predominantly linked with urban salubrity, from the Roman cloaca maxima to the Parisian motta papellardorum. The quantity of waste produced remained small and the methods for collection and discharge often unsatisfactory, which led to frequent denunciations of urban dirtiness. Neo-Hippocratic medicine, which considered the tainted environment and air to be the principal causes of urban excess mortality, prompted the implementation of new policies and management techniques in Europe to clean up the cities. In addition, the value of most urban excreta intended either for agriculture or industry increased. Thus, from about the 1770s to the 1860s, salubrity and excreta recovery went hand in hand. From the 1870s onward, the fertilizer revolution, the rapid development of coal and, later, that of the petroleum industry and the search for more convenient and plentiful materials, undermined the recycling industry. Although some cities at first tried to fight the devaluation of urban by-products, they gave up during the interwar years. What was once a source of profit became a cost to society, and, until the 1960s, the aim of waste management was to reduce this cost. The environment became the receptacle for waste. The 1960s and 1970s were marked by an environmental crisis, a growing concern for the limits of the planet and a criticism of the industrial city. In this context, waste was regarded as the symbol of the aberrations of a consumer society. The production of waste continued to grow and the sanitary accidents as a result left a deep impression. Waste policies were implemented with mixed results. Developing countries also began to suffer from this curse of developed countries.

Nitrogen, land and water inputs in changing cattle farming systems. A historical comparison for France, 19th-21st centuries

This paper provides an original account of the long-term regional metabolism in relation to the cattle rearing in western France starting by the precise formulation of animal diets at three key dates of the 19th, 20th and 21st centuries. We established links between the demand in fodder of the meat and dairy sectors and the necessary inputs of nitrogen, water and land as well as the land cover changes occurring on the affected local and remote cattle acreage. The average agricultural productivity for fodder supply is estimated at about 50 kg N/ha in the mid-19th, 54 kg N/ha in the early 20th and 150 kg N/ha at the turning of the 21st century. Jointly for the dairy and meat productions, the potential efficiency in the conversion of the vegetal into animal protein more than doubled over the studied period, passing from less than 9% in the 19th to 20% in the 21st century. The current cattle sector is sustained for about 25% by land situated beyond the regional frontiers and uses water at intensities that approach or exceed the availability of renewable water. The nitrogen pollution is expressed in terms of the Net Anthropogenic Nitrogen Inputs (NANI) and, by comparison to the N recovered in products, is used to define the N-Environmental Efficiency of the farming. We discuss the historical succession of the factors that contributed to the growth of the meat and milk production and make a comparison of the impacts and policy between the local and distant resources.

Urban Metabolism of Intermediate Cities: The Material Flow Analysis, Hinterlands and the Logistics-Hub Function of Rennes and Le Mans (France): Urban Metabolism of Intermediate Cities

Although urban metabolism has been a subject of renewed interest for some years, the related studies remain fragmented throughout the world. Most of them concern major cities (megacities and/or national capitals) and, more rarely, intermediate, medium‐sized or small cities. However, urbanization trends show that together with the metropolization process, another one is characterized by the proliferation of intermediate cities. We have studied the metabolism of two French intermediate cities for the year 2012: Rennes Metropole (400,000 inhabitants) and Le Mans Metropole (200,000 inhabitants). To this end, we used material flow analysis (MFA) based on the methodology developed by Eurostat, adapted to the subnational level. This has been made possible by the use, for the first time, of very precise statistical sources concerning freight. We have developed a multiscale approach in order to weigh the urban metabolism of those two cities and to compare it to other cases and larger territories. This allows a better understanding of the specific territorial metabolism of intermediate cities, their hinterlands, and their logistics‐hub function. We conclude with the “urban dimension” of social metabolism, and, thanks to the multiscale approach, to the debate regarding logistical hubs, dematerialization, and territorial autonomy.

La climopathologie aux XVIIIe et XIXe siècles

Sabine Barles, Die Klimatopathologie im 18. und 19. Jahrhundert ; Jahreszeitlich bedingte Hitze oder Feuchtigkeit trugen dazu bei, das das Leben in den ersten modernen Stadten die Gesundheit gefahrdete. Zunachst hat die Medizin sich dieser verderblichen Einflusse angenommen ; sie zog sich aus diesem Bereich zuruck, als die von Louis Pasteur ausgeloste Revolution und die sozialhygienischen Bewegung sich seiner annahmen.