A lightning strike in a mature pine forest sparks a wildfire of cataclysmic proportions. A young Tunisian street merchant, disaffected by corrupt, arbitrary authorities, sets himself afire which provokes mass protests culminating in the Arab Spring. A New York investment bank overextends itself on toxic subprime mortgages, bringing about bankruptcy and setting off a panic that paralyzes the global financial system.
In each of these cases—ecological, political and financial—a sudden, seemingly isolated event cascades into a systemic breakdown, a massive collapse. The suddenness, severity and scale of such events often catches everyone off guard. Nassim Nicholas Taleb, the irreverent philosopher-financier, has coined the phrase “black swan” to describe this phenomenon of the shockingly unpredictable.
With hindsight, surveying the wreckage, we often default to simple, compelling narratives as a post hoc prediction of the unforeseen. Alas, goes the lament, we should have seen it coming!
Take, for example, Niall Ferguson, the prolific Harvard historian who’s built a career on ruminating on the rise and ruin of great civilizations. In a 2010 Foreign Affairs article on “Complexity and Collapse,” Ferguson questions the conventional narrative of history: “What if history is not cyclical and slow moving but arrhythmic — at times almost stationary, but also capable of accelerating suddenly, like a sports car? What if collapse does not arrive over a number of centuries but comes suddenly, like a thief in the night?”
Ferguson argues that civilizations, whether dictatorial or democratic, are complex systems and as such have “the tendency to move from stability to instability quite suddenly. But this fact is rarely recognized because of the collective addiction to cyclical theories of history.”
What Ferguson, among others, fails to realize is that history is both slow and sudden, cyclical and abrupt. At the heart of complexity theory are the concepts of scale, over both time and space, and interdependence, that is, connectivity among multiple factors. That means a local event (small scale) can have a widespread impact (large scale), and a sudden event (very short time scale) can impact a historical trend (long time scale).
Complex systems evolve over time and can lose their resilience—their ability to continue to function in the face of a sudden shock. Indeed, a complex system may be subjected periodically to unexpected disturbances, but only when its loss of resilience reaches a certain threshold will the system breakdown to the point of collapse.
Lets go back to my first examples. Although their timing and location are unpredictable, lightning strikes happen all the time. But what causes one strike to spark a catastrophic wildfire? A number of factors are likely at work: first, global warming (a 200-year time scale) may have increased the average winter temperature, causing a beetle epidemic that kills large swaths of trees and adds fuel for a prospective fire; second, the forest itself (50-year time scale) may be very mature with a large amount of combustible kindling on the forest floor; third, the region may be experiencing an extreme seasonal drought (10-year time scale); and fourth, the lightning strike happens in the summer (one-year time scale), the driest season of the year. The confluence of these variables sets the stage for the unprecedented inferno.
So, was the fiery collapse of the entire forest ecosystem sudden? Only if you believe that the lightning strike was the primary cause of the wildfire. Yet a lightning strike of the same magnitude at the same spot during a wet spring month may cause only a small-scale forest fire. So, we can safely say that lightning strikes, in and of themselves, don’t cause devastating wildfires.
The concept of resilience is lost on Ferguson. “When things go wrong in a complex system, the scale of disruption is nearly impossible to anticipate,” he writes. “There is no such thing as a typical or average forest fire, for example. To use the jargon of modern physics, a forest before a fire is in a state of ‘self-organized criticality’: it is teetering on the verge of a breakdown, but the size of the breakdown is unknown. Will there be a small fire or a huge one?”
Actually, scientists can study the maturity of a forest, accumulation of deadwood, climate conditions and other factors to understand if an ecosystem is susceptible to a catastrophic fire. The structure and characteristics of a complex system determine its resilience.
The same is true of society. If sudden mass protests, violent unrest and assassinations trigger regime collapse, then the United States would have crumbled long ago. Yet the United States has been remarkably resilient to periodic shocks like the L.A. riots, presidential assassinations and terrorist attacks. Tunisia, Egypt, Libya and Syria also seemed robust enough to withstand or repress unrest in the past. Then, at some tipping point, the regimes became brittle. Understanding the resilience of a society and its political system is key to determining its vulnerability to collapse.
Complex systems, by their very nature, do not typically collapse from a simple, singular or sudden factor. Interdependence of multiple factors, over scales of time and space, is what causes catastrophic breakdown.
While we may never be able to predict sudden shocks—a lightning strike, terrorist attack or market meltdown—we can gauge the robustness of an ecosystem, society or financial system to take a severe beating and bounce back.