Our Fracture-Critical World

In our quest for hyper-efficiency, the modern world has lost most of its resilience.


The collapses we have all witnessed in recent years, from falling bridges to failing banks, could be avoided in the future if we gained a better understanding of how ecosystems work.

Consider the August 2007 collapse of the I-35W bridge in Minneapolis. Completed in the early 1960s, that bridge had what engineers call a “fracture-critical” design—with so little redundancy in its highly efficient and interconnected steel trusses that the entire structure fell after one gusset plate cracked due to overloading.

An ecosystem can collapse in the same way. Its elements can become so interconnected and efficient that the ecosystem can lose its resilience and rapidly decline. Ecosystems go through adaptive cycles, as the ecologist C.S. Holling has argued, but they return, like the replacement I-35W bridge, in a more resilient, less efficient and less interconnected form.

The parallel between ecosystems and the systems that we design should come as no surprise. We create our world in terms of how we see the world around us, and we have tended to focus, until relatively recently, on the efficiency and interconnectedness of nature. If the process of evolution can eliminate waste, we figured, why can’t we? This has led us to overlook another aspect of nature—its healthy redundancy and resilience—and to drive those qualities out of the world we design for ourselves, to our great misfortune.

This almost-obsessive focus on efficiency might not matter much if it only resulted in the occasional bridge collapse. But it has come to pervade most of the systems and structures upon which we depend, and we find ourselves in the midst of fracture-critical failures at a scale never seen before in human history.

Take our financial system, for example. Just as one gusset plate brought the I-35W bridge down, so too did the failure of a couple of investment banks—first Bear Stearns and then Lehman Brothers—set off a chain-reaction collapse of the credit and stock markets around the world.

We shouldn’t have been surprised by this meltdown. The global economy had become so interconnected and efficient that it had no more resilience than the trusses of the bridge. Regulators ignored signs of stress in the banks just as inspectors did the bridge’s bending gusset plates, while investors piled huge amounts of debt onto the financial system, like the added weight of paving equipment that contractors placed on the bridge before it fell. Our financial system will emerge from this crisis, but, like a recovering ecosystem, it will be less connected, less efficient and more resilient than before.

Adding to the urgency, we also have a fracture-critical food system, in which the failure of any one of the three dominant plants—rice, wheat and corn—could cause widespread starvation. We have a fracture-critical electrical grid, in which failures in a few places at once can bring down large sections of the grid and disrupt electrical service for extended periods of time.

Closer to home for many of us, we have a fracture-critical housing system, in which enough foreclosures, especially in economically homogeneous neighborhoods, can send the value of all the other nearly identical houses underwater, with homeowners paying more for their mortgages than their houses are worth, leading to further foreclosures.

We don’t have to look far to envision a more resilient future for ourselves. Humans have long lived this way: husbanding finite resources to ensure that future generations have enough. Cultivating renewable resources to maintain their quantity and diversity. Allocating desirable resources in ways that prevent over-consumption. And encouraging the enjoyment of infinite resources such as community, creativity and empathy.

This future will bring a new appreciation of ecosystems, not only as valuable in their own right, but also as a model for human systems. We’ll apply our knowledge of the natural environment to design more sustainable and secure human environments, less vulnerable to the catastrophic collapses that have come to characterize our current situation.

We will someday emerge from this adaptive cycle, hopefully with less hubris and with a newfound humility and renewed respect for nature.

This article is an abbreviation of a chapter in a forthcoming book on the I-35W bridge collapse, to be published by the University of Minnesota Press in spring 2010.

THOMAS FISHER is a professor and dean of the College of Design at the University of Minnesota. He has written extensively about design and sustainability. His recent book, Architectural Design and Ethics (Architectural Press, 2008), looks at the ethical aspects of leading more sustainable lives.