The notion of environmental space has much to offer to those who wish to advance sustainability and sustainable development. Based on two main principles, the recognition of environmental limits and a strong equity principle, it provides guidance, and a methodology, for 'making sustainability concrete', and a framework for the development of coherent and integrated policy from the global to the local level. However, important questions remain about whether and how it can and should be institutionalised, especially at the global level.
This paper will discuss three means, or rather approaches, by which the concept of environmental space could be institutionalised at the global level: the commercialisation of environmental space in the form of tradable entitlements, as exemplified by greenhouse gas (GHG) emissions trading schemes; global 'green planning', of which Agenda 21 and the adoption of the Millennium Goals can be seen as (weak) examples; and the adoption of a global income policy. Although the latter has hardly entered the international agenda, there are good reasons for considering this option seriously. All three options will be discussed and assessed on their relative strengths and weaknesses, especially with regard to their ecological effectiveness (the extent to which they prevent a further erosion of the ecological basis), equity (in terms of the relative shares of environmental space used by groups and individuals), feasibility (the availability and practicability of means of implementation and the political support basis for their adoption and implementation), and efficiency (their relative costs of implementation). But first, I will provide some further clarification of the notion of environmental space.
The notion of environmental space was first introduced by Horst Siebert in 1982. It has been defined as "The total space provided by the earth for our use without diminishing the possibilities for the future" (Davidson 1995), and has been advanced specifically with the aim to "make sustainability concrete" (Buitenkamp, Venner and Wams 1992, 17-18, Opschoor and Weterings 1994). Environmental space analysts set out to determine the total 'allowable' resource consumption on a geographical basis (depending on the resource in question), and to provide guidance to governments on the extent to which resource consumption within their territories should be reduced or can be expanded. It is based on two core principles: respect for ecological limits, and equal access to resources. To these, several other principles have been added, depending on the advocate or author (Carley and Spapens 1998, 8-9, Moffatt 1996, 50-52).
The first core principle, the need to respect ecological limits, is based on the idea that there are limits to the capacity of the earth to absorb the pollution and waste associated with resource exploitation and consumption ('throughput' of material). Although it is not possible to determine these limits with absolute precision, and they often only become apparent only once they have been transgressed, enough is known to be able to set indicative (and adaptable) targets. Environmental space advocates also concur with the precautionary principle: uncertainty is not an excuse for not accepting and setting limits. It should be noted that the argument about limits does not so much refer to the idea that the world is running out of resources, which has been characterised by some as a 'red herring' (Carley and Spapens 1998, 85). In most cases, limits are imposed by the 'new scarcity' (ecological limits)(Simpson, Toman and Ayres 2005), not by available reserves, although Hille and others note that, for a range of non-renewable materials, depletion may indeed pose a problem, providing a case for restrictions on consumption on the basis of absolute scarcity (Cohen 2007, Hille 1997, 15).
The second principle associated with the notion of environmental space is that all people (those living now and future generations) have equal rights to resource consumption (strong equity principle). …