Because of the shortcomings of money valuation, ecological economists favor physical indicators and indexes in order to judge the overall impact of the human economy on the environment. Therefore, we here leave aside monetary corrections to GNP, such as those of El Serafy (see above), or Hueting. These calculate the economic costs of adjusting the economy to socially negotiated norms or standards of pollution and resource extraction, in a ‘cost-effectiveness’ approach (meaning the analysis of the cheapest instrument in money terms in order to adjust the economy to such physical norms or standards). We also leave aside Cobb’s and Daly’s ambitious Index of Sustainable Economic Welfare (ISEW) (Daly and Cobb 1994[1989]), first calculated for the United States, which has inspired work in many countries, and whose end result is a figure in money terms strongly commensurable with GNP though often showing quite a different trend.

The main physical indexes of (un)sustainability discussed at present are as follows:

4.1. HANPP

HANPP (the human appropriation of net primary production) has been proposed by Vitousek et al. (1986). The net primary production (NPP) is the amount of energy that the primary producers, the plants, make available to the rest of living species, the heterotrophs. Of this NPP, humankind ‘coopts’ around 40 percent in terrestrial ecosystems. It is assumed that the higher the HANPP, the less biomass is available for ‘wild’ biodiversity. The proportion of NPP appropriated by humans is increasing because of population growth, and also because of increasing demands on land per person for urbanization, for growing foodstuffs, and for growing timber (‘plantations are not forests’ is a slogan of environmental activists in the tropics).

4.2. Ecospace

Ecospace and ecological footprints. Which is the environmental load of the economy, in terms of space? H.T. Odum posed this question, and later authors developed some answers. Rather than asking what maximum population a particular region or country can support sustainably, the question becomes: how large an area of productive land is needed (as source and sink) in order to sustain a given population indefinitely, at its current standard of living and with current technologies? Computations, not only for cities or metropolitan regions (whose ecological footprint is hundreds of times larger than their own boundaries) but for whole countries, show that some densely populated European countries (assuming per capita eco-footprints of 3ha.) or Japan or Korea (with per capita eco-footprints of 2ha.) occupy eco-spaces ten times larger than their own territories. This is the ‘appropriated carrying capacity,’ from which an ‘ecological debt’ arises. (For details, Wackernagel and Rees 1996.)

4.3. EROI

The term EROI, which stands for ‘energy return on (energy) input,’ also originates in H.T. Odum’s work. Is there a trend towards an increasing energy-cost of obtaining energy (Hall et al. 1986)? The idea of looking at the basic economics of human society as a flow of energy is well known to ecological anthropologists (through Roy Rappaport’s Pigs for the Ancestors and similar work). It goes back to Podolinski in 1880. Engels in 1882 exchanged correspondence with Marx on this topic. He denied the relevance of energy accounting for Marxian economics. Clearly, for an economy to be sustainable, the energy productivity of human work (i.e., how much energy is made available per day, by one day of human work) must be higher (or equal, if everybody is working) than the efficiency of the transformation of the energy intake into human work.

The energy productivity of a coal miner (wrote Podolinski) was much larger than that which a primitive agriculturalist could obtain, but this energy surplus from fossil fuels was transitory. Max Weber in 1909 had criticised Wilhelm Ostwald’s interpretation of economic history in terms of (a) an increased use of energy, (b) an increased efficiency in the use of energy, because economic decisions on new industrial processes or new products were based on prices, entrepreneurs did not pay attention to energy accounts per se. (No environmental auditing of firms was yet required.) Max Weber (whose book review against Ostwald was much praised by Hayek in later years), did not question energy prices from the environmental point of view as we would today.

In the early 1970s there were a number of studies on energy flow in agriculture, of which the best known were those of David Pimentel showing a decrease in energy efficiency in maize cultivation in the United Sate, because of the large energy input from outside agriculture itself. A new field was opened up by such studies on the efficiency in the use of energy, such as fuelwood, oil, and gas (Peet 1992), in different sectors of the economy, including the energy sector itself, taking also into account that increased energy efficiency might paradoxically lead to increased energy use, by reducing its cost (the Jevons effect). Such energy analysis has nothing to do, in principle, with the adoption of an ‘energy theory of value,’ or with the view that sources of energy are more problematic for sustainability than sinks for residues.

4.4. MIPs and DMR/TMR

The indicator of material input per unit service (MIPS) was developed at the Wuppertal Institute by Schmidt-Bleek. It adds up the materials used for production directly and indirectly (the ‘ecological rucksack,’) such as mineral ores, energy carriers like coal and oil, and all biomass (though not water, which is used in much larger amounts), including the whole ‘life-cycle’ down to the disposal or recycling phases.

This material input is measured in tons and it is compared with the services provided, sector by sector and, in principle, for the whole economy. For instance, to provide the service of one passenger per km, or to provide the service of living space of so many square metres, what amount of materials is involved, comparing different regions of the world, or historically. MIPS is useful as a measure of the material intensity of production but not as a measure of the toxicity of materials. The MIPS notion has been developed further in statistics published by the World Resources Institute in 1997 on the Direct Material Requirement and the Total Material Requirement (i.e., the aggregate tonnage, including in the TMR—the ‘ecological rucksacks’) coming into the economies of some countries such as the United States, Germany, The Netherlands, and Japan, both from domestic sources and from imports. This therefore tests the hypothesis of ‘dematerialization’ of production (Bunker 1996, Cleveland and Ruth 1998).

All the indexes mentioned here are measured in different units. How should a situation be judged in which, for instance, a synthetic indicator or index such as TMR improves while HANPP deteriorates, EROI decreases, and GNP grows? Commensurability would imply reducing such values to an encompassing super-value but this is not necessary in order to reach reasonable judgments by a sort of macroeconomic multicriteria evaluation or integrated assessment (Faucheux and O’Connor 1998).

1. Origins

2. Scope

3. Disputes on Value Standards

4. Environmental Indexes of (Un)sustainability

5. The ‘Dematerialization’ of Consumption?

6. Carrying Capacity and Neo-Malthusianism

7. Final Remarks on Transdisciplinarity

References