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|The Biomass Metabolism of the Food System: A Model-Based Survey of the Global and Regional Turnover of Food Biomass The food and agriculture system is among the largest anthropogenic activities in terms of appropriation of land and biological primary production, as well as alteration of the grand biogeochemical cycles of carbon, water, and nitrogen. Despite its importance in these respects, physically coherent descriptions and analyses of the food and agriculture system regarding the total turnover of fundamental flows (such as biomass) and resource use and efficiency of critical processes (such as animal food production) are relatively scarce. This article presents a survey of the current flows of biomass in the food and agriculture system. The survey gives a mass‐ and energy‐balanced description of biomass from its production on cropland and grassland through its transformations into animal and vegetable food products to its final conversion into respiratory heat, feces, and other residues. This assessment was carried out by means of a physical model that, for eight world regions, calculates the necessary production of crops and other phytomass (plant biomass) from a prescribed end use of food, efficiency in food production and processing, and use of system‐internal by‐products and residues as feed, feedstock, and food. The global appropriation of terrestrial phytomass production by the food system was estimated to be some 13 Pg (1.43 × 1010 short tons) dry matter, or 230 EJ (2.18 × 1017 Btu) gross energy (higher heating value), per year in 1992‐1994. Of this phytomass, about 8% ended up in food commodities eaten. Animal food systems accounted for roughly two‐thirds of the total appropriation of phytomass, whereas their contribution to the human diet was about 13% (both on a gross energy basis). The ruminant meat systems were found to have a far greater influence than any other subsystem on the food system's biomass metabolism, primarily because of the lower feed‐conversion efficiency (calculated as carcass produced by total feed intake, including pasture and other human‐inedible feedstuffs) of those systems.||The Biomass Metabolism of the Food System: A Model-Based Survey ...||Stefan Wirsenius||Journal Article||academic||2003||
Food and agriculture
Material Flow Analysis (MFA)
|Western European Materials as Sources and Sinks of CO2 Materials use is an important factor influencing carbon dioxide (CO2) emissions because significant amounts of carbon dioxide are released during the production of materials from natural resources, and because products and wastes can function as important sinks for CO2. This article analyzes the impact of Western European materials use on CO2 emissions. The material flows for steel, cement, petrochemicals, and wood products are analyzed in more detail. The analysis shows that particular characteristics of the materials system must be considered in the development of emission reduction strategies. It is important to select a relatively closed system for policymaking, as in Western Europe, in order to prevent unwanted transboundary effects. The materials stored in the form of products, and the net exports of materials, products, and waste limit the potential of a recycling strategy. Carbon storage in products and waste disposal sites is significant both for synthetic and natural organic materials, but is not accounted for in natural organic materials in current emissions statistics. Accordingly the emissions accounting practices should be modified to reflect the storage of such materials.||Western European Materials as Sources and Sinks of CO2||Gielen, Dolf J.||Journal Article||academic||1998||
Carbon dioxide (CO2)
Chemicals and fertilizers
Material Flow Analysis (MFA)