Tag: Sustainability

David Bello, Associate Editor over at Scientific American, has an interesting post up today looking at the supposed tensions between “resilience” and “sustainability”. His argument in a nutshell is that precisely the characteristics that make many urban systems resilient can also make them deeply unsustainable from an environmental point of view.

He’s right, sort of. But really what’s at stake here is a redefinition of how we build resilience into our urban systems.

It’s not so much a contradiction as an evolution. Let me show you what I mean.

As Bello points out, both “resilience” and “sustainability” are hot these days. Read any recent municipal planning document or press release and you’ll find them sprinkled about liberally like some kind of magic spice. 

But what happens when the two come into conflict? Think of fail-safes like combined sewer outflows (CSOs) that dump raw sewage into local streams when storms overwhelm infrastructure, or diesel generators that protect residents and businesses from failures in the electricity grid. Both are key (and common) examples of elements that increase the ability of a system to weather a crisis, but at significant environmental costs.

I was working in Durban (South Africa) when storms ravaged the coastal city flushing effluent out along the city’s beaches and then later when the national electricity grid collapsed (due to poor management, not weather) leaving residents and businesses reliant on diesel generators for months. The tradeoffs between resilience and sustainability were glaring.

So, is the current adulation of the two concepts really just a trendy contradiction in terms? That’s the lure that Bello uses to hook the reader. Contradictions are captivating. He changes tune later though, hinting at the way in which conceptions of resilience are shifting: Green roofs and bioswails can create resilience just as well as CSOs, and they purify water rather than polluting it.

But that’s where he ends. To me that’s really just the beginning.

City’s have always cared about “resilience”, even if they called it something else. It only takes one failure to make the case that systems need to have some form of redundancy built into them. The question is how you provide that redundancy. What Bello is calling a contradiction is really just one old approach to resilience rubbing up against a new one.

Up until very recently, urban resilience was created by offloading localized stresses onto the surrounding environment. It’s no surprise that solutions designed following that model conflict with attempts to make cities more environmentally sustainable. But the contradiction lies in the method, not the goal of resilience itself.

More recent approaches to resilience emphasize synergies between built and natural systems. Cities have moved in that direction not simply because green is trendy, but because it yields better results. Engineered natural storm water systems (like green roofs or bioswails) address multiple forms of resilience simultaneously: they protect sewage systems from flooding, and they also reduce the urban heat island effect and increase resilience to heatwaves. Choosing decentralized solar over diesel adds redundancy, while also increasing air quality. 

Definitions of resilience have also been broadened to include issues like health, food security, and social cohesion. Looking just at bricks and pipes only capture part of the story.

So can cities be both green and resilient? Yes. But to get there means changing the ways we’ve provided resilience in the past, and making the most of solutions that provide for multiple forms of resilience simultaneously. 

photo: bioswale, Greg Raisman