Just sustainability

The concept of sustainability is well described as “a big, sloppy term for a big, complex subject” (Prugh et al, 2000, p.2). The meaning of ‘sustainability’ is highly contested and subject to a wide variety of (often self-serving) definitions.

So how can this “big, sloppy” concept – and all that it tells us about global limits to resource consumption and waste production – be translated into recommendations for practical action?

One way of achieving this translation that appears in the policy documents of various green parties around the world is to work with the notion of ‘carrying capacity.’ In particular, carrying capacity features as a key principle of many green population policies.

Unfortunately there is often a serious defect in the way carrying capacity is applied, as explained in an article by Steve Vanderheiden (2008). Usefully, though, for those who wish to see sustainability policy become a reality, Vanderheiden also shows how sustainability policies be formulated differently, along lines that take proper account of issues of justice.

The problem with carrying capacity

Carrying capacity is defined in my Concise Oxford Dictionary as “the number of animals, or crops which a region can support without degradation.” Other definitions I found around the web are very similar. Vanderheiden says that

[the idea’s] immense appeal is owed to its intuitive plausibility, capturing something essential about the proper understanding of sustainability. (p.438)

The problem with the definition given above is that it is seriously flawed. It incorrectly suggests that this ‘region’ is effectively a closed system with a finite and fixed ecological capacity.

Now the entire planet as a whole can be considered a closed system but, in the human context in particular, no ‘region’ can be considered closed – the carrying capacity of particular localities is significantly altered by trade. Vanderheiden uses the example of famine to illustrate the point:

It is possible both for a territory that produces little or no food to avoid food shortages permanently as well as for famine to occur in a region that produces sufficient food to feed its human population … no ‘natural law’ forbids the delivery of food aid to starving peoples. (p.439)

But if sustainability policy is based on the principle of a region’s carrying capacity, some disturbing conclusions follow. Since some regions are well resourced, their residents have considerable opportunities for high consumption lifestyles; meanwhile the residents of other, less well-off regions face permanent hardship. A mere geographical accident of birth arbitrarily determines whether a life of hardship or comfort will follow. In policy terms it suggests that

populations residing in some territory have an exclusive moral right to the resources located within their borders such that they may legitimately exclude others from access to them. (p.440)

This way of thinking may appear logical to some environmentalists (Garrett Hardin seemed rather fond of it) but I agree with Vanderheiden that it is an indefensible prescription for sustainability.

The solution – ecological footprint

Rather than the focus on ecological supply, which the concept of carrying capacity implies, a much more logical and defensible basis for sustainability policy focuses on the “disparate sources of demand for ecological goods” (p.449).

The measure required is the ecological footprint, defined as

the amount of biologically productive land and sea area an individual, a region, all of humanity, or a human activity requires to produce the resources it consumes and absorb the waste it generates.

As Vanderheiden points out, unlike carrying capacity this measure

does not imply any privilege for those living in resource-rich bioregions … the relevant facts for sustainability are not where one’s resources originate or where one’s waste ends up, but how much one consumes and how much waste one produces. (p.448)

As has been discussed previously on well sharp, ecological footprint forms the basis of Andrew Dobson’s concept of ecological citizenship. Vanderheiden doesn’t go in that direction explicitly, but he does refer to the “cosmopolitan obligation” (p.450) indicated by the footprint measure and the conceptions of justice which that implies.

Drawing on Dobson’s work, he suggests that ecological footprint forces us to think beyond our ‘immediate geographic location’ or even our ‘region’ and so demonstrates

the sort of global interdependence that is necessary for grounding duties of cosmopolitan justice – which as Dobson notes, must not only undergird principles but must also motivate political action – illustrating chains of causal responsibility from unsustainable acts in one place to bad consequences or diminished opportunity elsewhere. (pp.451-452)

With this in mind, Vanderheiden concludes his article by considering how the footprint can be used to generate a just policy framework for global sustainability. He suggests turning the use of the footprint around, from being a measure of past demand to an indicator of appropriate future allocations of ecological space. This leads us to a proposal (originally put forward by Tim Hayward) for a tax upon those who take excess ecological space.

Summing up

Carrying capacity can only be properly used at the global level, as Vanderheiden shows, but those party policies using the concept are not (so far as I can discover) global policies; they are intended to apply within the borders of the nation/state/province/etc in which the particular party operates. Carrying capacity based policies that focus on ecological supply within national boundaries (or similar) generally lead to prescribed numerical limits to national populations. Vanderheiden shows that such prescriptions are insupportable.

Policy which grows from a different basic measure, such as the ecological footprint, focuses our minds properly on the highly inequitable levels of consumption of different population groups. Some very different conclusions emerge from this sort of analysis – and proposals that we might like to think of as the beginnings of just sustainability.


Thomas Prugh, Robert Costanza, & Herman Daly (2000) The local politics of global sustainability. Washington DC: Island Press.

Steve Vanderheiden (2008) Two conceptions of sustainability Political Studies, 56(2), 435-455.


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