On Sustainability Metrics for Environmental Management

The concept of sustainability is associated with the statement from the World Commission on Environment and Development, 1987: ?? development that meets the needs of the present without compromising the ability of future generations to meet their own needs?? Sustainability is, therefore, about the likelihood of the world persisting in a dynamic regime that is supportive of human society. But without at least semi-quantitative means of measuring progress in a meaningful manner, it is difficult to implement any sustainability strategy in any practical sense. There is, therefore, a need for scientifically sound metrics to provide quantitative measures that assess the degree to which the system is or is not on a path towards sustainability, and whether management actions taken are or are not effective in maintaining the system on a sustainable path. Inherently, sustainability questions involve a complex and interacting system that has many dimensions including ecological, economic, social, and engineering aspects. One might never fully understand such a complex system, but there is an immediate need for methods to analyze and manage it. We plan to discuss the subject of sustainability metrics generally, and then illustrate the concepts with the case of four metrics for use in environmental management: ecological footprint, emergy, green net regional product, and Fisher information. These respectively represent human burden on the environment, energy resources flow in the system, economic vitality, and overall system order and function. One should note that these metrics are meant to represent system processes and qualities that must be preserved for sustainability in a system that is dynamic, evolutionary, and, perhaps, cyclic. The illustration concludes with a discussion of the San Luis Basin Sustainability Project where we have collected data that allow us to compute these four metrics as a function of time, and to observe trends with time for about twenty years. Lastly, the outline of a management strategy on a regional scale using these concepts and metrics will be discussed.