Toward a definition of sustainability

Sustainability is not an absolute, independent of human conceptual frameworks. Rather it is always set in the I context of decisions about what type of system is to be sustained and over what spatiotemporal scale. :rhere is a duality of the material system itself, as opposed to human frameworks for communication or management action. Exclusive focus on the material system gives the decision-maker an impossible number of choices, and no definitions; exclusive focus on scale and type gives narrowly directe.d capricious action that ignores lessons from the material system. An ide,al is guided by the principal physical and biological material flows, as the scientist erects a rich system definition that explicitly links different types of system, like landscape and ecosystem, across a range of scales, in a coherent complex management scheme. Sustainability is not a matter of degree, because the material imbalances of incomplete sustainability will bring all down like the ancient failure of Sumerian agriculture through salination. True, sustaining at one scale may deny sustainability at another, but if it is in a scaleexplicit framework, trade-offs can be calculated and weighed. Sustainability must work with natural processes, but they are not those of the pristine system. Rather management must accommodate to new structures and their patterns of process which naturally emerge far from equilibrium as a result of a substantial human presence. In a world with 5 billion people, managing towards a pristine system is irresponsible.