In our review of the academic literature we identified 16 characteristics of urban systems and processes that supposedly foster resilience (Table 3
). Hypothesized characteristics of resilient processes include: inclusivity, transparency, and equity in stakeholder engagement approaches [9
], as well as processes that are flexible, forward looking, and iterative [6
]. Resilience processes are also valued for being knowledge or information driven, meaning that they integrate traditional, as well as scientific knowledge into their frameworks and approaches and provide equitable access to information for all parties interested [36
]. Research in the climate, urban, and resilience fields has postulated that there may be general characteristics of resilience, as well as generic/general forms of adaptive capacity that promote resilient systems [39
]. Examples of general resilience characteristics include: diversity, iterative/feedback mechanisms, transparency, collaboration and integration, social-ecological integration (also coined environmental focus), efficiency, and adaptive capacity enhancement [42
]. There is also a series of characteristics that are believed to be important for assessing specific resilience to unique climate impacts. Examples include redundancy in the case of drought, robustness in the case of hurricanes and extreme winds, and decentralization in the case of flooding [46
4.1. Tensions between Resilience Characteristics in Theory and Practice
In the urban resilience literature, robustness
is about a system’s ability to resist change or disturbance: it is essentially about “strength” [22
]. In the survey, the characteristic robustness
was defined as “ensuring municipal-wide infrastructure and organizations can withstand external shocks and quickly return to the previous operational state”. Robustness
is very similar to the notion of engineering resilience. If robustness
is seen as a desirable characteristic of a system, it implies a wish to maintain the status quo. This is not controversial when thinking about certain scales or engineered systems; no one wants a building to collapse in a hurricane. But there are many other more problematic, but nonetheless robust, aspects of modern cities (i.e., inequality or the reliance on fossil fuels). Many critics of resilience discourse and policy argue that resilience, particularly when applied to social systems, is inherently conservative and often employed to prevent positive transformations [62
]. In response to these criticisms, some resilience scholars have incorporated transformation into their conceptualizations of resilience [65
]. In academic theory, the trend seems to be away from static, engineering resilience with its emphasis on robust systems [6
] towards these more flexible and adaptive forms of resilience. However, the high importance ascribed to robustness
by survey respondents, as well as the numerous references in the definitions to ”bouncing back”, suggest that it persists as a dominant line of thinking in ‘on-the-ground’ urban resilience activities.
According to the local practitioners surveyed, the characteristic forward-thinking was second only to robustness in terms of average importance. For the purposes of the survey, forward-thinking was defined as “Integrating information about future conditions (i.e., population, economy, weather) into community planning and decision-making.” In the definitions written by practitioners, almost one in ten specifically mentioned the future, and nearly 15 percent of responses suggested the need for advanced planning. For example, one respondent defined resilience as “No surprises for changing landscape. Advanced planning to make us better prepared”. Another wrote “… as change occurs, it has been anticipated and planned for such that no or minimal disruption occurs.”
While the academic literature also emphasizes preparing for future changes, some resilience scholars caution against too much emphasis on prediction or the use of single scenarios to understand future threats. Instead, focus is placed on techniques such as scenario planning [7
] and the selection of actions that will perform well under a wide array of potential future conditions (known as robust actions in the scholarly literature) [66
]. This assessment did not evaluate the types of tools or techniques that local practitioners are using as part of their advanced planning, but we would argue that it is important to provide practitioners with appropriate tools and the support needed to effectively utilize them.
Another area of discrepancy relates to the relative importance of adaptive capacity
. In the urban climate resilience literature, building resilience is often equated with enhancing adaptive capacity
]. However, survey respondents did not rate adaptive capacity
among the most important characteristics. Furthermore, the term adaptive capacity
was not explicitly used in any respondents’ definitions; however, 21 respondents did allude to it.
In the academic literature, flexibility
is one of the most commonly cited resilience characteristics [9
means that a system can function under different circumstances and absorb change [6
]. In the survey, flexibility
was defined as “making municipal operations and plans flexible and open to change when needed”. Unfortunately, efficient adaptation and robustness
against certain threats may come at the expense of the flexibility
to deal with unexpected future changes [35
]. If practitioners are primarily focused on robustness
, as the survey results suggest, urban systems may not be sufficiently flexible to deal with unexpected climate impacts or other stressors. There were two respondents who explicitly called out flexibility
: One noted that moving towards climate resilience would mean “increasing flexibility” and another stated that resilient jurisdictions should “exhibit nimble behavior”. Overall, however, flexibility
was not highlighted in the practitioners’ definition of resilience. This seems logical given that local institutional structures and decision-making processes are rigid, making it difficult to create flexible, adaptive systems capable of integrating emerging information and changing as needed. Going forward, devising solutions to build more flexible systems will likely remain an important area of research.
is frequently cited in the literature as a key characteristic of resilience. This relates back to ecological theory, which suggests that biodiversity enhances the ability of an ecosystem to withstand change [51
]. Looking specifically at the urban climate change context, Tyler and Moench [6
] differentiate between “spatial diversity”, meaning system components are widely distributed to reduce the likelihood that the whole system is impacted by a single disruption, and “functional diversity", where there are multiple avenues for meeting critical needs. Diversity
can also be applied to governance systems, with the idea being that polycentric systems that engage a wide array of stakeholders are more resilient [9
]. For the purposes of the survey, diversity
was defined more broadly as “Ensuring a diverse economy, infrastructure, and resource base (e.g., not relying on single mode of operation, solution, or agent/institution).” Given the emphasis on diversity
in the resilience literature, it was surprising that more respondents did not rate it as important, and only one explicitly mentioned diversity
in their definition.
Related to the concept of spatial diversity, scholars have argued that decentralized systems are more resilient than centralized ones because when something disrupts a central unit, the entire system is jeopardized, whereas in a decentralized system it only impacts a small portion. In the literature, arguments are made for decentralization
in both physical systems (like electricity generation) and governance [35
]. Admittedly, some resilience scholars caution that decentralized governance may not be universally preferable [14
]. Survey respondents clearly rated decentralization
, defined in terms of “decentralizing services, resources, and governance, e.g., solar or wind energy; stronger local governance”, as less critical for resilience than all the other 15 criteria. Similarly, none of their definitions mentioned decentralization
For most resilience scholars, a certain level of functional redundancy
is thought to enhance resilience; the argument being that when you have units with overlapping functions, if one falters, it can be easily substituted [24
]. The definition provided for redundancy
in the survey was “having back-up systems, infrastructure, institutions, and agents”. Like diversity
is a characteristic that can be applied to both technical systems, like electricity infrastructure, and social networks. Only one respondent mentioned redundancy
in their definition, and then only in the context of “water and power systems”.
This mismatch between theory and practice with respect to redundancy
could stem from the fact that redundancy
has a somewhat negative connotation, and supporting it may seem to conflict with cost or even eco-efficiency [20
]. In fact, scholars have cautioned that efficiency
may be at odds with redundancy
] and that “efficiency, as traditionally conceived, does not necessarily promote resilience” [71
]. Yet efficiency
still tends to have a positive connotation in popular discourse, and is sometimes cited in the literature as a characteristic of resilient urban systems [22
Some urban resilience scholars such as Ahern [51
] have argued that resilient systems should be “safe-to-fail” as opposed to “fail-safe”. In the survey, this was represented by the characteristic predictable
, defined as “ensuring that systems are designed to fail in predictable, safe ways”. Looking specifically at urban climate resilience, Tyler and Moench [6
] define “safe failure” as “the ability to absorb sudden shocks (including those that exceed design thresholds) or the cumulative effects of slow-onset stress in ways that avoid catastrophic failure. Safe failure also refers to the interdependence of various systems, which support each other; failures in one structure or linkage being unlikely to result in cascading impacts across other systems.” Practitioners did not seem to consider this characteristic to be important, and “predictability” or “safe-to-fail” was not mentioned in any of the resilience definitions. In fact, one respondent even commented “why would anyone design a system to fail”, indicating the mismatch between what theoretically is conceived of as being important to resilient systems and what is achievable in practice.
According to the literature, efforts to build resilience should be conducted iteratively, providing opportunities for participants to take stock of what has been learned and apply that knowledge to the next step [6
]. As defined in the survey, an iterative process
is “one whereby feedback and lessons learned are continually used to inform future actions”. This characteristic emphasizes the importance of learning, which “includes not only the mobilization and sharing of knowledge but also such factors as basic literacy and access to education. These kinds of factors have been identified empirically as contributing to community resilience to disasters” [6
]. Iterative learning is also an important part of the popular adaptive management approach, which is closely tied to resilience theory [59
]. While the iterative process
characteristic was not rated as important, on average, as other characteristics, the terms “understanding”, “education” or “learning” did appear in almost 10 percent of respondents’ definitions. For example, one respondent wrote that resilience means “a commitment to … learning new skills”, another “an educated community”, and still others noted that residents need to be educated on climate change.
Implementing tight feedbacks
—or as defined in the survey: “building mechanisms so that information is rapidly fed back to decision-makers or system operators”—can support the iterative process, learning, and ultimately, the resilience of urban systems [24
]. As previously noted, a number of practitioners referred to education or learning in their conceptualizations of resilience, but none of them mentioned feedback
directly. On average, respondents also rated this characteristic relatively low in importance.
are also both process- or governance-related characteristics. The meaning of transparency
as described in the survey is “ensuring that all municipal processes and operations are open and transparent”. Survey respondents were prompted to think of inclusivity
as “Ensuring that all residents have access to municipal infrastructure and services, including providing an opportunity for all people to participate in decision-making processes”. While transparency
are not as commonly associated with resilience theory as other characteristics such as diversity
, both are mentioned in the literature as being important for continued engagement and good governance. For example, Tanner et al. [58
] note that a “delivery of climate resilient urban development relies on a municipal system that maintains a relationship of accountability to its citizens, and is open in terms of financial management, information on the use of funds and adherence to legal and administrative policies.” Researchers also emphasize the importance of inclusive, participatory decision-making processes that engage those groups most heavily impacted [6
]. This emphasis was not mirrored in practitioners’ definitions of resilience; neither transparency
were mentioned in any of the survey responses.
4.2. Synergies between Theory and Practice
While we do see a number of inconsistencies and unresolved issues with respect to resilience characteristics in the academic literature and amongst the surveyed practitioners, there are some promising areas of agreement. Within the urban climate change literature, the concept of resilience is most often traced back to the field of ecology, and therefore the relationship between humans and the environment are often central to definitions of resilience. The survey results reveal that practitioners also consider being environmental, defined as “protecting natural systems and assets”, as quite important for resilience. It was, on average, the third highest rated characteristic. Moreover, several respondents specifically mentioned “ecosystem health”, “ecosystem integrity”, “ecosystem services”, “natural resources”, and “biodiversity” in their definitions of resilience.
While resilience theory is often praised for its focus on the interconnections between social and ecological systems, a common critique leveled against resilience theory generally, and urban climate resilience more specifically, is that it fails to address issues of equity [72
]. These scholars critically ask “resilience for whom?” and argue that because resilience theory traditionally uses a systems approach, it ignores inequalities and trade-offs within the system boundaries [74
]. It is therefore interesting that practitioners rated the importance of equity
, defined in terms of “ensuring that the benefits and impacts associated with actions are felt equitably throughout the municipality”, fairly high. While the word equity
was not used in any of the respondents’ definitions, a number of them did specifically mention assisting vulnerable or less powerful groups within their communities. For example, one respondent wrote that resilience “would also mean we are better prepared to help our citizens respond to the impacts of climate change, especially those least able to take action on their own, e.g., low-income households, the elderly, the young, those with respiratory & other health problems.” Another respondent noted, “our priority is to build resilience in our institutions, systems, infrastructure, and communities [that] must protect the poor, elderly, young and ill against hazards and shocks.”
The characteristic integration
, as defined in the survey, requires “making sure that plans and actions are integrated across multiple departments and external organizations.” Jabareen [7
] argues that dealing with the uncertainties and complexities of climate change necessitates an “integrative approach”, one that fosters collaboration across a multitude of public and private stakeholders, agencies, and organizations. Additionally, adaptation planning may be more effective if it is integrated into other local plans, with plans at the state or federal level, or combined with efforts of surrounding municipalities [21
]. A number of the survey respondents specifically mentioned integration
in their definitions. For example, one noted that resilience suggests an approach “to foster integrative—cross sector, cross discipline—solutions.” Another definition did not use the term integration
but noted that to be resilient they would need to “include climate adaptation in all of our future planning functions—capital plans, resource allocation, stormwater, etc.” Similarly, another respondent highlighted the importance of “regular communications between all sectors and with and among the community”.
Overall, scholars and practitioners seem to agree on the importance of supporting ecological systems, equity, and integrated planning for urban resilience, so there is some common ground for collaboration or knowledge exchange. However, there are a number of other theorized characteristics that practitioners see as relatively less important, or that have been called into question by other scholars. In particular, practitioners’ emphasis on robustness, which is associated with an engineering or “bounce back” conceptualization of resilience, may be problematic.