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RESILIENCE AS A SUSTAINABILITY METRIC
Citation:
Pawlowski**, C. W., A Mayer**, AND C. McCord. RESILIENCE AS A SUSTAINABILITY METRIC. Presented at A.I.Ch.E Annual Meeting, San Francisco, CA, November 16 - 21, 2003.
Impact/Purpose:
To inform the public
Description:
The concept of sustainability comprises many issues, including social equity, environmental impacts and economic viability. Different indicators of sustainability will emphasize different issues. We focus on the environmental aspects of sustainability since human activity relies on a reliable flow of products and services from functioning ecosystems. It is often assumed that ecosystems respond more or less linearly to human or external pressure: a little more pollution, and the ecosystem is a little more degraded. However, recent ecological research has uncovered examples of ecosystems that suddenly and sometimes catastrophically change in thier composition and in their dynamics in response to incremental changes in external pressure. Such changes can have dire consequences on human society. Resilience is one of several terms ecologists use to characterize the response of an ecosystem to disturbances. Two definitions of resilience have become prominent in the literature, both of which derive from the dynamic systems theory concept of stability. One refers to the speed of return of a system to its prior, undisturbed steady state. The other refers to the magnitude of disturbance an ecosystem can absorb before it falls into the basin of attraction of a fundamentally different steady state. We argue that these conceptualizations of resilience do not adequately caputre the interaction between state displacement and disturbance effects on ecosystems because they use state displacement as a proxy for disturbance. Here we suggest a theoretical measure of resilience that measures both the effects of state displacement and the amount of disturbance an ecosystem can tolerate. Presentation of these resilience concepts is made in the context of a simple model of a lake's response to pollution.