LCA Food 2012 in Saint Malo, France! - Manifestations et colloques ...

GROUP 5, SESSION B: FOOD PRODUCTS 8 th Int. Conference on LCA in the
Agri-Food Sector, 1-4 Oct 2012
135. Spatial food-print to supply livestock products to Paris, 19 th -21 st
centuries
Petros Chatzimpiros
Paris Interdisciplinary Energy Research Institute (PIERI), Université Paris Diderot, France, E-mail: petros.chatzimpiros@univ-paris-diderot.fr
When cities import food to sustain their metabolism, they virtually import land resources from the surrounding
local and distant rural territories that generate the food. We refer to this vital physical substrate of urban
metabolism as the spatial urban food-print (or food-print). The food-print locates where the food and animal
feed crops are grown and its size depends on various parameters that can be divided into three categories:
urban diets, crop yields and “feed to food” conversion ratios (Chatzimpiros and Barles, 2010).
In this proposal we determine the food-print to supply cereals and livestock products (beef, pork, chicken,
dairy products and eggs) to the Paris metropolitan area since the early 19 th century. Over this period, the
food-print of fast growing occidental cities like Paris was the substrate of fundamental changes in the structure
of agro-ecosystems and the common ground for transformations in both agricultural productivity and
urban diets. Until the early 20 th century, food supply to Paris is calculated from data records of the city’s
food markets. After that date, data become scarce due to progressive increases in the number of food supply
chains and retail markets and, as for today, urban food consumption is not specifically known for any French
city. Since the 1960s though, dietary discrepancies across France are low enough to allow deriving urban
food supply from data on national food availability (production, plus imports, minus exports). We thus derived
a time series of food supply to Paris since the early 19 th century which we express as nitrogen (e.g.
protein) and convert into land requirements for food production – the food-print of Paris – using data on food
and feed crop yields (Statistique agricole annuelle) and nitrogen conversion efficiencies (NCE) in livestock
production. For pork, beef and dairy production we used model-derived data of NCE for the early 19 th , 20 th
and 21 st centuries (Chatzimpiros, 2011). For chicken and egg production, we used data covering the second
half of the 20 th century (Lambier and Leclercq, 1992, Smith, 1997, Smil, 2002). We interpolated/extrapolated
data on NCE over time proportionally to key variables such as biomass production rates.
Fig. 1 shows Paris population and its food-print since the early 19 th century. Between 1850 and 2008, population
grew 7-fold, food supply 8.5-fold and the food-print 2-fold. In Fig. 2, per capita supply (kg N/cap) is
plotted with land requirements for production (ha/kg N) (land requirements decrease with time). The resulting
curves show increases in the consumption of livestock products with low land requirements. As long as
beef was the cornerstone of agrarian systems (