As “sustainability” proves difficult to define precisely, some have turned to the concept of “resiliency” as an alternative. While this has the advantage of substituting a more concrete characteristic -- robustness in the face of challenge -- for the ambiguous term “sustainability,” it is not enough by itself to provide analytical rigor.
The concepts of “resilience” and “vulnerability” are closely linked. Both refer to the sensitivity of complex systems to catastrophic failure from a minor change in input. Some complex systems are “robust” in that they do not tend to catastrophically fail with minor changes; others are “vulnerable” -- as, for example, a surge in a single power line causing a massive blackout across the northern United States and parts of Canada. The same system may be robust to a series of individual challenges, but eventually be pushed into a regime where a single change results in catastrophic failure.
Thus, many biological communities are robust to initial challenge, but eventually a small additional challenge results in a significant shift in community structure and function -- the proverbial straw breaks the camel’s back. Obviously, such behavior has serious implications for managing earth systems across all scales, from the local salt marsh that one wishes to keep healthy, to trying to understand whether, and under what circumstances, global climate change might discontinuously shift oceanic circulation patterns, with potentially significant human impacts.
Unfortunately, complex systems and their behavior are generally not yet well understood. In particular, it is not clear how one should interact with complex systems of all kinds -- from natural resource regimes such as the Everglades or the Baltic, to human systems such as economies and technological systems -- to maintain their desired stability. But research on complex systems and resiliency at places like the Santa Fe Institute continues to deepen our understanding (readers might examine some of the relevant literature, such as Kauffman’s
At Home in the Universe).
Nonetheless, the focus on the resiliency of complex systems can sharpen the sustainability dialogue significantly. For one, it drives analysis towards the specifics of the systems in question, and their characteristics and behavior, and thus encourages intellectual rigor rather than rhetoric. Moreover, it challenges the rather static visions that “sustainability” can encourage, substituting the concept of self-organizing systems at the edge of chaos with evolving systems building increasing levels of order and complexity.
But shifting conceptually from sustainability to resiliency in self-organizing systems is not enough. For the real question remains: resiliency of what, to what? More precisely, what characteristics of the system do we want to be resilient, and against what?
This question should be considered in light of another important characteristic of complex systems: their relevant boundaries are defined by the query we pose. Thus, for example, if I ask about New York City’s police, the relevant system are the familiar jurisdictional boundaries of the City. If, however, I ask about New York City’s water provisioning activities, the relevant system takes in much of New York State.
Consider in this light the Internet. The resiliency of such a “scale-free network” -- which is indeed energetically open and self-organizing -- to random loss of links, is extraordinary. On the other hand, a scale-free network is very susceptible to deliberate attack, because it usually has a limited number of hubs that are highly connected, and which form the system’s backbone. In short, it is very resistant to accident, but very vulnerable to attack. How we evaluate its resiliency, therefore, depends on why we ask the question, and requires us to dialog with the system in question, fostering a rigor of analysis and a depth of knowledge that is otherwise all too frequently lacking from the discourse on sustainability. (Interested readers can find more detail in Barabasi, Linked).
And so it is with many highly integrated systems, such as the climate system, biological systems at all scales, material cycles, and human systems such as cities. We need to understand their resiliences and vulnerabilities in detail, with explicit reference to the properties and behaviors we are interested in. Asking hard questions about resilience and vulnerability is a step in a difficult but necessary direction.
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Brad Allenby is Environment, Health, and Safety VP for AT&T, an adjunct professor at the University of Virginia’s Engineering School and Princeton Theological Seminary, and Batten Fellow at the University of Virginia’s Darden Business School. The views expressed herein are those of the author, and not any institution with which he is associated.