The concept of resilience has received a lot of attention in recent years, perhaps because we face increasing challenges at all levels, from the personal to the global. Resilience is seen as an important way of responding to those challenges, or having the capacity to respond.
The word stems from the Latin resilire, meaning to jump back or recoil.
It seems to have first been used in engineering, but has been taken up by disciplines as diverse as ecology, child psychology, community and social development, and urban planning; the British Standards Association even has a standard for organizational resilience.
In psychology, the term refers to "the process of adapting well in the face of adversity, trauma, tragedy, threats or even significant sources of stress," according to the American Psychological Association.
Importantly, they and others are clear that resilience is not something you are born with, but that it is to a large extent a learned behaviour and an attitude - and once learned, it stays with you for life.
Research has provided us with a good idea of what promotes resilience in people, especially young people: having caring and supportive relationships within and outside the family. If children feel loved and have people around them they can trust, they are likely to be able to handle challenges and succeed in managing them.
As Sherri Torjman of the Caledon Institute noted in her 2007 book, Shared Space: The Communities Agenda, building resilience requires communities to invest in both personal-capacity development - "the skills, abilities and assets of individuals and households" - and community infrastructure - "the supply of amenities and resources that contribute to well-being."
In fact, there is a reciprocal and mutually reinforcing relationship between resilient people and resilient communities.
In more recent times, the concept of resilience has been applied to social as well as natural systems, communities, organizations, even societies and nations.
A recent book from the Canadian Institute for Advanced Research describes it as the ability of these social systems "to sustain and advance their well-being in the face of challenges to it."
Indeed the lead authors consider social resilience to be "a key characteristic of successful societies" - and, we might add, communities.
Resilience in ecosystems has a somewhat different meaning than it does in psychology.
In 1973, C.S. Hollings not only defined ecological resilience, but, importantly, he showed that one way natural systems handle changes and disturbance is that they can flip into a new and different stable state.
This is an important shift in our thinking about resilience, because we don't necessarily want to "bounce back" if that means we return to the situation that was the problem - or caused the problem - in the first place.
Instead, we need to "bounce forward," out of the situation that is causing the stresses and into a new, better, stable state.
Which brings us to the topic of healthy cities, where many of these concepts come together. Healthy cities consist of people, both as individuals and gathered in communities, as well as a multitude of public, private and non-profit organizations, all embedded within natural systems. If cities - or more precisely, the people in cities - are to remain healthy in these challenging times, they not only need to be resilient themselves, they need their communities, organizations and ecosystems to be resilient also.
Because ultimately, we are only as resilient and healthy as the natural ecosystems in which we are embedded.
So we have to stop - and reverse - the stresses we are placing on these systems, which means shifting to an ecologically sustainable way of life.
We might not be able to make natural systems more resilient, but we must avoid stressing them up to and beyond their tipping points; we don't want to push them to the point where they shift into a new stable state that might not be compatible with human civilization.
As we face the many challenges of the 21st century, whether as individuals, communities, cities or entire societies, we need to bounce forward to a healthier, more just, more sustainable future, not back to the 20th-century conditions and way of life that have created the problems we face.
Dr. Trevor Hancock is a professor and senior scholar at the University of Victoria's school of public health and social policy.