INDICATORS OF MATERIAL FLOWS: CONCEPTUAL FRAMEWORK, USE
In order for an economic system to function and produce goods and services necessary for meeting human
needs, it behaves similarly to a living organism. It absorbs substances from the surrounding environment and
transforms them into products, but ultimately all the materials are transformed into some kind of waste and
emitted back into the environment. The economic system above all absorbs fossil fuels, other mineral
resources, biomass and water on the input side while emits emissions to the air, water and solid wastes on
the output side. This flow of materials, which has mostly had one-way direction so far (only 10-15 percent of
wastes is recycled globally) (Brown, 2001), is referred to as an industrial or socio-economic metabolism
(Baccini and Brunner, 1991; Fischer-Kowalski and Haberl, 1993; Ayres and Simonis, 1994).
The theory of socio-economic metabolism considers socio-economic system to be a sub-system of the
environment connected to its surroundings through energy and material flows. These flows burden the
environment and along with land use and other biological and social factors they belong to the key source of
environmental problems. If the volume of these flows was reduced, a decrease in environmental pressure
could be expected (Schmidt-Bleek, 1993; Weizsäcker et al., 1996; Bringezu et al., 2003).
Environmental pressure is already related to the extraction of mineral resources. The crude oil extraction
involves leakages both during extraction phase and oil transportation. The negative impacts on the
environment take place during the underground and surface extraction of minerals as well (Neužil, 2001).
These impacts include air emissions (mostly of CO, CO2, SO2, SO3, CH4, NO, NO2, and PM), disturbance
of water regimes and water contamination, land appropriation and contamination, direct disturbance of
biotopes, noise, vibrations and changes in landscape. Other pressures are related to pre-processing of
minerals – sorting, crushing, rinsing and drying.
Much bigger environmental burden is related to the consumption of mineral resources. It is besides others
caused by the fact that while number of mineral resources entering the economic system is limitted, the
number of pollutants emitted due to the consumption of minerals has been growing (Spangenberg et al.,
1999). Moreover, these pollutants enter the environment by huge number of gateways: each dumping place,
each smokestack and each exhaust pipe presents such a gateway. Consumption of mineral resources
contribute, for instance, to global climate change, depletion of stratospheric ozone, eutrophication,
acidification, radioactive pollution, etc. (Giljum et al., 2005).
The environment is able, to some extent, to neutralize the environmental pressure imposed on it by human
society in relation with the consuption of materials. If the rate of use of renewable resources is lower than the
rate of their renewal, or wastes are emitted in such volumes, which can be absorbed by the environment, any
severe damage to the environment should not take place (Bringezu, 2006). This rate is, however, often
exceeded (World Resource Institute, 2005) and there is a problem with non-renewable resources. Their
sustainable rate of use is difficult to determine, above all with respect to their maintenance for future
So far, there has been a positive relation between meeting human needs and pressure exerted on the
environment. When standards of living went up, this pressure was growing as well, even though it was often
shifted abroad in the case of developed countries (import of resources or transfer of “dirty“ industries to
developing countries). The environment of developed countries was thus cleaned up (Schütz et al., 2004). On
the global level, however, the human society recorded an unprecedented growth in annual material and
energy inputs and outputs over the 20th century (Adriaanse et al., 1997). As argued above, this was also
accompanied with the growh of environmental pressure. Developed countries within their strategies of
sustainable development therefore adopted a goal to break the relation between pressure exerted on the
environment and economic growth, i.e. to meet human needs and improve the standard of living. This
phenomenon is shortly called decoupling (from longer “decoupling of environmental pressure from economic
growth“) (OECD, 2002).
Economy-wide material flow analysis, meaning and use of material flow indicators
Material flow analysis belongs among the methods, which allow for quantification of socio-economic
metabolism and assessment of environmental pressures related to the use of materials. Nowadays, the
attention is above all drawn to economy-wide material flow analysis (EW-MFA). EW-MFA was developed
during the 1990s by various research institutes and organizations (principally the World Resources Institute,
the Wuppertal Institute for Climate, Environment and Energy, the Department of Social Ecology at the Faculty
for Interdisciplinary Studies of the University in Klagenfurt, Japanese National Institute for Environmental
Studies, and Eurostat), and then standardized in a methodological guide (Eurostat, 2001).
The Czech Statistical Office focused on compilation of indicators of material input and material consumption.
These are the best developed ones from the methodological point of view and are based on available data.
Methodology for their compilation is described in the methodological chapter. Below is the summary of their
possible uses (OECD, 2008):
Overall physical scale of the economy and total environmental pressure related to use of materials
To study overall physical scale of the economy over time, it is advisable to refer to material flow indicators in
absolute terms. These indicators are considered proxies for environmental pressure related to use of
materials and energy.
Equity and equal resource sharing
Relating material flow indicators to population allows for a comparison of material use and disposal of
pollutants from the viewpoint of equity and equal resource sharing. Generally speaking, all people should
have equal rights to consume natural resources and use the environment for assimilation of waste flows
(Moldan (ed.), 1993).
Land use intensity
Consumption of materials can be related to the area needed for materials production. This issue has above
all been developed for renewable resources and is well-known as a concept of Ecological Footprint
(Wackernagel et al., 1996) and Human Appropriation of Net Primary Production (Vitousek et al., 1986). For
cities, area for production of consumed materials is always larger than the area of a particular city. This is
caused by high population density and low share of bioproductive areas. For countries and regions, the
situation may be reverse.
Efficiency of use of materials and decoupling of environmental pressure from economic growth
Relating input and consumption material flow indicators to national account aggregates, such as gross
domestic product (GDP), allows for measuring the efficiency by which an economic system transforms used
materials into economic output. Such indicators reflect material productivity, i.e. the ratio of GDP over the
material flow indicator, or material intensity, i.e. the ratio of the material flow indicator over GDP. These two
measures are compatible with the inverse time development.
Assessment of material intensity and productivity is complementary to analysis of decoupling of
environmental pressure from economic growth (see text above).
Shifting of environmental pressure between states and world regions
Many industrialized countries have decreased their amounts of domestically extracted and processed
materials by importing them from other countries. The shift of pressure related to extraction and processing of
these materials has taken place between states and world regions mainly to the detriment of developing
countries (Schütz et. al., 2004). To capture these shifts, it is necessary to study physical imports and exports
and related flows.
Foreign material dependency and material security
Material flow indicators can be further used for monitoring of foreign material dependency. Economies fulfil
their material demands partly from their own territory and partly by importing materials from other countries.
The higher the share of imports in domestic material input and domestic material consumption is, the more
the economy is susceptible to incidental shortage of particular commodities abroad, increase in their price or
to upheaval of other barriers to foreign trade.
Potential for future waste flows
All input material flows, which are going to be accumulated in form of physical stocks, will change into waste
flows sooner or later. Knowing the volume of physical stocks in particular cities, regions and states and their
durability, one can model waste flows to come. This is useful for planning of capacities for waste treatment
within the waste management plans both in short, medium and long-term perspective.
Use of renewable and non-renewable materials
It is acknowledged internationally that the sustainable supply of materials should be based on renewable
materials to a certain extent. This refers not only to scarcity of non-renewable materials but also to the fact
that use of non-renewable materials is generally linked to comparatively higher negative impact on the
environment (EEA, 2006). This issue can be captured by input and consumption material flow indicators by
monitoring ratios of renewable materials in particular indicators.
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