Several critiques of the ecological footprint exist (notably VROM-Council 1999, Van Kooten and Bulte 2000, van den Bergh and Verbruggen 1999, Pearce 2000). These reviews contain a mix of positive and negative comments relating to the application of the methodology as well as suggestions for improving its structure and use.

It is important to address these briefly both to understand the limitations of the methodology, its strength and weaknesses, and to assist in assessing the various applications of the methodology within the EU.

Here we paraphrase 10 key points listed by Van Kooten and Bulte (2000) and use these as a framework for comment. Their comprehensive critique is arguably the most harsh of those listed above and was used by Pearce as the basis for his submission to the EU Commission DGXI. One of the co-founders of the ecological footprint concept, Dr. Mathis Wackernagel, has also had the opportunity to address the points raised in a corresponding submission to the EU Commission (Wackernagel 2000) and here we draw on his comments augmenting these with our own thoughts and experiences. The reader is also referred to Chapter 6 of 'Sharing Nature's Interest' (Chambers, Simmons and Wackernagel 2000) which addresses these and additional points.

Click on a criticism to be taken to the response:

Criticism 1 - Footprint accounts are incomplete

Criticism 2 - Applying Carrying Capacity concepts to human populations is flawed. Evidence has shown that (a) humans, unlike other animals, can and do increase the carrying capacity of their environment to meet their needs and (b) certain regions and communities seem to be living beyond their local carrying capacity now with few ill effects.

Criticism 3 - The very process of aggregating land types to calculate a footprint assumes substitution - yet this is not possible.

Criticism 4 - Carrying capacity is irrelevant since resource yields can be increased in the case of renewable resources, and depletion profiles can be extended by technology in the case of non-renewable resources.

Criticism 5 - Carrying capacity calculations have limited relevance when trade is possible since the scarce resource can be imported in exchange for another asset in which the exporting nation has a comparative advantage.

Criticism 6 - Certain economies that are highly urbanized (Netherlands, Singapore, Hong Kong) can never be sustainable since they can never meet their ecological demands from their own land.

Criticism 7 - Footprinting is a survivability concept not a sustainability concept. Survivability is about maximizing the time available on Earth for human species, independently of the quality of that existence.

Criticism 8 - Calculating the fossil fuel footprints in terms of area needed to absorb the corresponding CO2 is inadequate according to some critics.

Criticism 9 - There are substantial uncertainties about how to calculate the land areas required to offset waste flows.

Criticism 10 - Footprint accounts make no distinction between land uses that are sustainable and those that are not.

1. Footprint accounts are incomplete

Ecological Footprint Analysis does not claim to account for all human impacts on the environment. Instead it prefers to offer a conservative underestimate whilst acknowledging that other impacts exist. Most obviously, the accounts focus on resource consumption, with the exception of water, and underestimate the impacts of waste products.

However, several footprint studies have addressed both of these shortfalls. Chambers et al (2000) demonstrate two methods of incorporating water consumption into footprint accounts. The same publication presents a study which includes footprint estimates for several pollutants.

Other studies have tackled the complex task of accounting for pollutants other than carbon dioxide, for example, Folke et al 1997, Wackernagel et al 1997 though they remain excluded from National footprint calculations. The main hurdle to further integration of pollution accounting would seem to be a lack of reliable research data on the way in which pollutants interact and affect bioproductivity. Further discussion on this issue is contained within a paper by Holmberg, Lundqvist, Robért and Wackernagel (1999).

There is also some confusion amongst critics of the method as to what the footprint is intended to account. The footprint typically accounts only those resources which are part of the biosphere’s cycles. It is implicitly assumed that the use of heavy metals and hazardous chemical (those which are persistent, bio-accumulative or toxic) should either be eliminated or must be handled in totally closed loops which do not involve release into the natural environment. Studies have shown that the impact on bioproductive capacity of, for example, heavy metals are massive and usually swamp other effects of consumption. The natural assimilation rate of Copper, for example, is 42mg per square metre per year . The footprint of a kilogram of copper would therefore be 2.38 ha-years. The footprint of a kilogram of PCB's is an impressive 2,000 ha-years (Krotscheck & Narodoslawsky 1996).

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2. Applying Carrying Capacity concepts to human populations is flawed. Evidence has shown that (a) humans, unlike other animals, can and do increase the carrying capacity of their environment to meet their needs and (b) certain regions and communities seem to be living beyond their local carrying capacity now with few ill effects.

Criticism (a) is based on a misunderstanding of how footprinting accounts for changes in biocapacity. As the footprint is a 'snap shot' measure, reflecting the supply and demand at the time of the analysis, future effects (such as increases or decrease in biocapacity) would only become apparent in subsequent analyses.

Criticism (b) ignores the fact that populations can exceed local carrying capacity either temporarily, by running down natural capital, or more permanently, by importing or appropriating capacity from elsewhere. Take the example of a fishing community dependent on a local lake for their food. They can over-fish the lake, temporarily increasing supply, by catching smaller and smaller fish. This will impact on the ability of the fish population to sustain itself leading to decline in stocks. This is of course what has happened on a wider scale in European waters where arguments have raged over the gauge of fishing nets which will allow the immature females to escape. Another option for the fishing community is to simply import produce from elsewhere, either fish or another protein substitute, thus appropriating carrying capacity form elsewhere.

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3. The very process of aggregating land types to calculate a footprint assumes substitution - yet this is not possible.

This is a complex point raised in different forms by various commentators. Basically, this comment is based on a misunderstanding about the nature of the footprint as a measure of impact based on current biocapacity calculations. Aggregating information into a single indicator need NOT imply that the elements being measured are interchangeable in any real sense. For example, MTOEs (Million Tonnes of Oil Equivalent) is a common unit used for aggregating the energy content of different fuel types to derive a overall indication of energy consumption. Aggregating in this way does not imply that the fuels are in any way interchangeable - natural gas cannot substitute for diesel, for example.

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4. Carrying capacity is irrelevant since resource yields can be increased in the case of renewable resources, and depletion profiles can be extended by technology in the case of non-renewable resources.

Indeed, carrying capacity can be altered: both eroded as in the case of desertification, and enhanced as in the case of careful management schemes. That’s why ecological footprints are always compared to the biocapacity of a given year (as mentioned earlier). In fact, as footprint accounts point out, technological efficiency is one possible strategy to reduce humanity’s draw on nature (as long as the efficiency gains are not outpaced by an increase in consumption).

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5. Carrying capacity calculations have limited relevance when trade is possible since the scarce resource can be imported in exchange for another asset in which the exporting nation has a comparative advantage.

Footprint accounts do not argue against trade. They point out that not all countries can be net-importers of ecological capacity if global overshoot is to be avoided. Footprint accounts make ecological trade imbalance visible and show to what extent nations depend on net imports of ecological services. Further, Pearce’s interpretation that shifting to imports from high-yield areas will reduce a country’s overall footprint is incorrect. From a global perspective, this is a zero-sum game at best. And in fact, in our accounts, a shift to imports from higher-yield areas does not reduce the importer’s footprint.

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6. Certain economies that are highly urbanized (Netherlands, Singapore, Hong Kong) can never be sustainable since they can never meet their ecological demands from their own land.

Of course, urbanised economies are more likely, by definition, to need to import resources to meet their needs. This does not mean they can never achieve sustainability, it just means that they will have a more dispersed footprint which will have a certain transportation 'overhead'.

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7. Footprinting is a survivability concept not a sustainability concept. Survivability is about maximizing the time available on Earth for human species, independently of the quality of that existence.

Certainly footprint estimates are a minimum requirement for sustainability. In other words, living within global carrying capacity is necessary but not sufficient for sustainability. It may be desirable to increase the footprint to allow for a higher quality of existence.

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8. Calculating the fossil fuel footprints in terms of area needed to absorb the corresponding CO2 is inadequate according to some critics.

The area included for CO2 sequestration represents the degree by which the planet would need to be larger in order to cope with anthropogenic CO2 output. Finding other ways to combat atmospheric CO2 accumulation would open dramatic possibilities for reducing humanity’s footprint. Calculations for various forms of renewable energy are included in Chambers et al (2000).

Another method of calculating the fossil fuel footprint is to assess the biological area necessary to produce a substitute. This would lead to even larger footprints.

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9. There are substantial uncertainties about how to calculate the land areas required to offset waste flows.

The science of accounting for various pollutants is in its early stages and by omitting these footprint studies underestimate environmental impact. Examples of studies where the footprints of wastes have been included are referred to earlier.

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10. Footprint accounts make no distinction between land uses that are sustainable and those that are not.

This is correct. But as mentioned previously changes in productivity due to unsustainable land use do appear in future estimates of biocapacity. If activities in one year lead to an increase in desertification, for example, then the bioproductive supply will decrease in subsequent years.

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