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An Emergy Systems View of Sustainability: Emergy Evaluation of the San Luis Basin, Colorado
CAMPBELL, D. E. AND A. S. Garmestani. An Emergy Systems View of Sustainability: Emergy Evaluation of the San Luis Basin, Colorado. JOURNAL OF ENVIRONMENTAL MANAGEMENT. Elsevier Science Ltd, New York, NY, 95(1):72-97, (2012).
This paper is one of a series of six papers to be submitted to by the Journal of Environmental Management to report the results of a joint NRMRL/NHEERL project to develop indicators of sustainability. This project is seen as one of the major products of the USEPA program on sustainability. The current rising interest in sustainable systems within the agency makes it possible that this project and this paper will have a considerable impact on future research. The final outcome and judgment must await the test of time.
Energy Systems Theory (EST) was used to provide a context for understanding and interpreting sustainability. We propose that “what is sustainable” for a system at any given level of organization is determined by the cycles of change originating in the next larger system. Furthermore, the pulsing paradigm determines the cycles of change and governs ecosystems rather than succession to a climax state (i.e., a steady state) that is sustainable. Therefore, every decision-maker’s first priority should be to know where their system resides in the cycles of change that govern it. This theory was examined by performing an emergy evaluation of the sustainability of the San Luis Basin (SLB) regional system. This region contains a fully developed agricultural system with crop and livestock production, and food and animal waste processing components and it serves as a hinterland, in that it exports raw materials and primary products to more developed areas. Emergy indices calculated for the SLB from 1995 to 2005 revealed the relative sustainability of the system, its well-being, and whether it was moving toward or away from more sustainable states: (1) in 1997; the SLB could support 50.7% of its population at the current standard of living on renewable emergy alone, while under similar conditions the U.S. could support only 4.8% of its population; (2) the total emergy used by the SLB system, a measure of system well-being, was remarkably stable (coefficient of variation = 0.05) over the 11 year period; (3) sustainability of the region as indicated by renewable emergy as a percent of total use declined 4%, whereas, the renewable carrying capacity declined 6% over the study period. In contrast to other indices, the Emergy Sustainability Index (ESI), which considers the benefits gained by the larger system and the potential for local environmental damage, increased 34% over the period. The ESI showed that the relationship of the SLB with its larger system became more sustainable in some years (ESI > 2.0) and moved toward being more unsustainable in others (ESI < 2.0).