مقیاس و توپولوژی در پارادایم پایداری اقتصاد محیط زیست

An ecologically sustainable scale of the economic system requires inclusion of spatial-temporal dimensions and topological relationships. While Herman E. Daly and Marcus Stewen have deliberated some of the issues surrounding economic scale in their papers (“Allocation, distribution and scale: Towards an economics that is efficient, just and sustainable” [Ecol. Econ. 6 (1992) 185], “The interdependence of allocation, distribution, scale and stability—A comment on Herman E. Daly's vision of an economics that is efficient, just and sustainable” [Ecol. Econ. 27 (1998) 119] and letters to the editor [Ecol. Econ. 30 (1999) 1], [Ecol. Econ. 30 (1999) 2], they do not address spatio-temporal constraints on ecological processes. Although Daly frames the scale of the economy based on sustainable throughput of resources relative to the environment, the pragmatic approach to defining this sustainable scale must incorporate other dimensions of scale. While Daly [Ecol. Econ. 6 (1992) 185], [Ecol. Econ. 30 (1999) 1] correctly promotes a logical sequence of policy instruments, scale should indeed elicit dependence from allocation and distribution decisions. Stewen's [Ecol. Econ. 27 (1998) 119], [Ecol. Econ. 30 (1999) 2] arguments included that these instruments have co-evolutionary interdependencies, but such arguments do not guarantee economic nor ecological sustainability. A more useful definition of sustainable economic scale includes spatial and temporal dimensions, scale constraints and topological relationships as they are framed by ecological components and processes. The spatial scale of the global economy is large, but temporally the global economy is diminutive: two characteristics that typically define catastrophic events in ecological parlance. Using a spatio-temporal framework, Daly's boat analogy can be extended to real-world linkages and possible solutions through supplementing the current view of economic scale with spatio-temporal distance and topology.

The debate between Daly, 1992 and Daly, 1999 and Stewen, 1998 and Stewen, 1999 continues to improve how a sustainable scale of economic structures and systems is defined. In this commentary, we argue that ecological and economic sustainability imply both intragenerational spatio-temporal distribution and allocation issues as well as relations of trade formed between units and framed by topological linkages. Since there is a need to incorporate space over which economic activity is undertaken, we elaborate Daly's (1992) definition of economic scale based on comprehensive scale definitions (such as Csillag et al., 2000 and Gibson et al., 2000). We agree with Daly's (1992, 1999) premise of a logical sequence of economic policy instruments that promotes scale to be the primary instrument required in decision-making for sustainability. Stewen's (1998, 1999) view of interdependence contributes to the idea of mutual reliance of policy tools. However, according to hierarchical scaling paradigms (for ecological context see Allen and Hoekstra, 1992), allocation and distribution must be dependent on scale, although these former policy instruments may indeed be mutually interdependent. While containment of economic instruments can be determined, the idea of sustainable dependence remains insufficient without understanding constraints of ecological systems and topological relationships. We, therefore, argue that a sustainable scale of economic systems requires applied knowledge of the spatio-temporal constraints of ecological systems and linkages.

That economists are considering economic scale is heartening to spatial scientists who spend their careers researching space and scale issues. Daly's concept of economic scale is a suitably parsimonious model, providing a best point of departure for discussions regarding sustainability and indeed, for enriching the model in order to apply it. However, it is essential to clarify the terminology of scale in economics to bring it into line with the current science of scale (see also Levin, 1992, Goodchild and Quattrochi, 1997 and Marceau, 1999). Some research, such as transforming the discount rate to spatial dimensions (Perrings and Hannon, 1997, Steininger, 1999 and Perrings and Hannon, 2001) and the ecological footprint analysis (Wakernagel and Rees, 1996), does indeed incorporate the value of the spatial dimension. Coupling the scale issue (both spatial and temporal) with economics is paramount for attaining a richer understanding of sustainability and the distribution of both economic and ecological impacts. Intragenerational issues of spatial scarcity and heterogeneity of allocation and distribution comprise one of the two critical scale elements in a framework of sustainability. The other is temporal scale with respect to ecological turnover times and the rate at which we use resources and dispose of wastes, together with how future generations will be affected by environmental lags. Inseparably alloyed to the scale issue are topological relationships in ecological systems, which require respect for, and maintenance of, their integrity and services. Thus, sustainability is a scale and topology issue, requiring not just size of the economy in resource use per capita, but such an ecological value linked over space and time. These issues, in general, emphasize the need for increased multidisciplinary collaboration and integration of research by ecologists and economists. It is encouraging to be further enlightened and challenged by commentaries such as those provided by Daly and Stewen in continued refining of the understanding of sustainability.