The word "sustainability" has come to dominate environmental discourse, employed to mean a condition in which we take no more from our environment than the environment is able to restore. It's a reasonably goal, but a limited one. Sustainability is a static concept: it says nothing about change, or improvement. McDonough's point is that "sustainable" is hardly a condition worth celebrating; at best, it's the maintenance of the status quo.

It seems to me that what we should be striving for is an environment -- and a civilization -- able to handle dynamic, unexpected changes without threatening to collapse. This is more than simply sustainable, it's regenerative and diverse, relying on both a capacity to absorb shocks and to co-evolve with them. In a word, it's resilient.

If we're to survive the 21st century, we need to be striving for environmental and civilizational resiliency.

In a "sustainable" environment, we live in constant fear of greed, accident or malice tipping the balance away from sustainability, returning us to the spiral of over-consumption and environmental depletion. Ironically, the goal of environmental sustainability is highly likely to put us on the path of ongoing environmental management. To an extent, this is already true -- ecologist Daniel Janzen argues that we're better off thinking of the environment as a garden to be tended than as wilds to be preserved -- but sustainability as a goal means constant vigilance. It's not simply that the environment can no longer be considered "wild;" in the sustainability paradigm, the environment can only be considered a subject. A sustainable world is one that manages to avoid imminent disaster, but remains perpetually on the precipice.

The underlying problem with the concept of "sustainability" is that it's inherently static. It presumes that there's a special point at which we can maintain ourselves and maintain the world, and once we find the right combination of behavior and technology that allows us to reduce our environmental footprint to a "one planet" world, we should stay there. For some sustainability advocates, this can include limiting ourselves technologically, as suggested by the frequency with which such advocates dismiss "techno-fixes" as simply allowing us to continue to behave badly. More broadly, as a strategic goal, sustainability pushes us towards striving to achieve success within boundaries; the primary emphasis of the concept is on stability.

"Resiliency," conversely, admits that change is inevitable and in many cases out of our hands, so the environment -- and our relationship with it -- needs to be able to withstand unexpected shocks. Greed, accident or malice may have harmful results, but (barring something likely to lead to a Class 2 or Class 3 Apocalypse), such results can be absorbed without threat to the overall health of the planet's ecosystem. If we talk about "environmental resiliency," then, we mean a goal of supporting the planet's ability to withstand and regenerate in the event of local or even widespread disruption.

Like sustainability, resiliency is a strategic concept, intended to guide how choices are made. But resiliency doesn't presuppose limitations; rather, it encourages the diversification of capacities, in order to be responsive to uncertain future problems. We can think of this as "strategic flexibility" or "maintaining our options," but it comes down to avoiding being trapped on a losing path.

When applied directly to environmental strategies, resiliency may appear similar to sustainability in superficial ways. Both sustainability and resilience would encourage aggressive moves to greater energy efficiency, for example. The similarity of tactics belies a divergence of intent, however; for sustainability the purpose is to reduce our impact to below a certain threshold, while for resilience, it's to increase the resources available to meet future problems. We see overlap like this because resiliency embraces the near-term goal of sustainability, inasmuch as resiliency recognizes that the depletion of planetary resources and ecosystem diversity is a self-destructive process.

For me, environmental resilience is a much more satisfying philosophy than environmental sustainability because of its emphasis on increasing our (our planet's) ability to withstand crises. Sustainability is a brittle state: unexpected changes (natural or otherwise) can easily cause its collapse. Resilience is all about being able to handle the unexpected. It does not ignore the need to be "sustainable" in the most general sense, but does not see that as a goal or end-point in and of itself. Sustainability is about survival. The goal of resilience is to thrive.