Introduction: Why Resilience?

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U.S. Forest Service, Southwestern Region, Kaibab National Forest / CC BY-SA 2.0
Complex ecosystems provide valuable insight into resilient practices, exhibiting “adaptive cycles” of growth such as the periodic regeneration of forest floors through natural fires.

Guest Editor for the Resilience Issue

While it is clear that the pace and pattern of global economic growth is unsustainable, we are slow in responding to this challenge. Sustainability advocates offer visions of a utopian future in which human needs are fulfilled and resource consumption is balanced with planetary capacity. But, in a turbulent world, the future seems increasingly unpredictable. Human societies are struggling to cope with present-day challenges ranging from climate change to political conflicts.

We have learned that the traditional tools of probability-based risk management are no longer adequate to cope with the complexity and turbulence of today’s world, in which disruptions are often unknowable and unforeseen. Unexpected crises seem to be arriving more frequently. As our global systems become more tightly coupled and volatile, we are increasingly challenged to maintain stability, let alone to pursue the transformative changes needed for sustainability.

This issue of Solutions is devoted to an emerging topic that may be a necessary condition for achieving sustainability. While there are many definitions of resilience, it can generally be defined as the capacity for a system to survive, adapt, and flourish in the face of turbulent change and uncertainty.1 In short, this means the ability to overcome adversity and bounce back. For individuals, resilience implies resourcefulness and strength of character. For communities and corporations, resilience implies preparedness and agility. At a national scale, resilience is closely linked with the security and sustainability of critical resources, including water, energy, food, minerals, and other valuable ecosystem services.

Although resilience is sometimes confounded with sustainability, in fact they are complementary. Sustainability tends to focus on long-term goals and strategies, while resilience tends to focus on preparing for unexpected disruptions that may destabilize an otherwise sustainable system. Indeed, improving resilience is actually the first step on the journey to sustainability. Some basic principles of resilient systems are summarized in Box 1.

Resilience appears to be a fundamental characteristic of living systems, including both human and ecological systems. Nature is resilient at every level—from the functioning of a single cell, to the evolution of a species, to the intricate balance of a food web. Living things are resilient because they are able to adapt to both abrupt and gradual change. Networks of living systems are even more resilient, although they may be vulnerable to cascading events such as disease epidemics.

In contrast, systems engineered by humans, including software, machines, buildings, and infrastructure, tend to be more brittle—vulnerable to sudden failure or gradual decay. We believe that one of the primary challenges faced by modern society is to “design for resilience”—to improve our capacity to cope with inevitable, often unforeseen disruptions. After all, a company or a city can also be considered a living system.

One source of inspiration is observing the natural world. Engineers have emulated nature’s ingenious designs through “biomimicry,”2 and likewise, companies are gaining insights about alternative business models from the study of ecosystems. This type of “eco-mimicry” is exemplified in the practice of “industrial ecology,” whereby companies seek closed-loop solutions for beneficial re-use of waste materials—inspired by the patterns of energy and material flow in ecosystems where virtually nothing is wasted.3

Resilience has been studied in many different fields including medicine, ecology, engineering, urban affairs, finance, supply chain management, and disaster preparedness. Research suggests that complex, self-organizing systems continually evolve through an “adaptive cycle” of growth, crisis, transformation, and renewal; for example, mature forests are periodically destroyed by fire or vermin, and then regenerate.4 Ecologists define resilience as the capacity of a system to tolerate disturbances while retaining its structure and function.5 Similarly, psychologists define human resilience as the ability to transform adversity into a growth experience.6 By integrating knowledge from these many fields, we can begin to develop a unified science of resilience.

The articles in this issue are authored by a diverse group of distinguished researchers and practitioners, spanning a variety of disciplines. They offer pragmatic approaches for strengthening the resilience of human and natural systems, including industrial enterprises, energy systems, supply chains, urban infrastructures, agricultural systems, and the ecological resources upon which all of these systems depend. They describe emerging tools for better understanding resilience, and provide insights based on real-world experience. They also carry a message of hope—that honing the basic characteristics of resilience, including foresight, adaptability, and diversity, will make us better fit for the long and winding journey to sustainability.

Box 1: Principles of System Resilience

  • Resilience is an intrinsic characteristic of all living systems.Living systems are purposeful, complex, adaptive, and self-organizing. They operate at many different scales—ranging from individual cells, to higher organisms, to sophisticated communities, to entire ecosystems.
  • Resilient systems exhibit awareness of and response to disruptions. A living system is able to sense gradual disturbances or sudden threats, and to respond via behavioral, functional, or structural adaptations that enable it to persist and preserve its identity (e.g., “fight or flight”).
  • The evolution of living systems is influenced by cycles of change at multiple scales. Every system is coupled with subsystems (e.g., components), higher-order systems (e.g., environments), and related systems (e.g., competitors). The associated cycles of change may be fast (e.g., power failures) or slow (e.g., global warming).
  • Resilient systems typically have corrective feedback loops to maintain a dynamic equilibrium. Disruptions (e.g., flooding) can shift a system away from equilibrium, or cause it to collapse. In response to disruptions, a system may cross a threshold and undergo a “regime shift” that leads to a different equilibrium state.
  • Self-organizing, self-aware systems can design for inherent resilience. Human-designed systems (e.g., cities or enterprises) can learn to identify potential disruptions and to design their assets so that they can better absorb extreme events (e.g., graceful degradation rather than shocks) and adapt to a changing environment.