Urbanization and urban areas belong to a set of worldwide, multiscale phenomena that are profoundly altering the relationship between society and the environment, and affecting both urban and earth system sustainability and resilience in complex ways and at alarming rates. In recent decades, sustainability, resilience and transformation have become key concepts aimed at understanding and responding to an array of looming challenges posed by urbanization and environmental change. Yet, even though definitions and approaches to these concepts are ever-changing and highly contested, they revolve around common themes and ask large and compelling questions, such as these: How, with our growing world population, can we thrive (or even survive) on a warming planet with its degrading ecosystems? What kind of urban (or rural) lives do we want, and what kind of world could provide for those lives into the future? Furthermore, of critical importance to moving sustainability and resilience into practice, what capacities do we need to foster that will enable us to survive, or to transform our ways of living and thrive, both on and with our increasingly warm planet? [1
As compelling metaphors that convey the interactions and dependencies between urban areas and the ecosystems on which they depend, the evolving concepts of urban sustainability and resilience are associated with an expansion of research around sustainability and resilience science [3
], and with national and transnational initiatives such as Local Agenda 21, 100 Resilient Cities and the Habitat III New Urban Agenda
, which attempt to move this science into the policy action arena. Through these initiatives, urban actors seek to develop strategies for environmental protection, economic prosperity, inclusivity, and community well-being, while increasing their cities’ resilience to both chronic and acute physical, social, and economic challenges [5
While such work has greatly influenced officials and actors in city-regions to pursue diverse projects and actions to understand and manage their own sustainability and resilience challenges [7
], consistent definitions of sustainability and resilience have remained elusive, because existing concepts are subject to widely differing framing and interpretations. Furthermore, there has been little research focusing on how different interpretations of these concepts intersect, complement, or contradict each other. Nor are the implications of those intersections and differences known. It is clear that this uncertainty of terms must also affect actions seeking to enhance the capacity of urbanites, as questions of capacity devolve to the question of capacity for what? In order to know what capacities urban actors must draw on to create sustainability and resilience, or to measure this capacity, it is most important to know what these terms mean, or what they can mean, in an operational context. Yet, however elusive the terms, in order to move out of existing trajectories of environmental degradation and risk, urban actors will need to transform themselves, their urban communities, and their cities’ relationships with the environment in purposeful, and conscious ways.
Similar to such social problems as justice, urban sustainability and resilience, far from being resolved issues, are procedural and shifting concepts, that are repeatedly framed, resolved, and contested anew. Within these shifting conceptualizations, cultural values, economic, and political considerations play key roles in defining sustainability and resilience goals, thresholds, and outcomes [1
]. In order to shed light on how these shifting interpretations intersect, complement or contradict each other, we begin by briefly describing some of the theoretical threads underlying the practice of urban sustainability and resilience. Afterward, we will explore what these intersections and contradictions imply for research, and for practices [11
] aimed at improving human and ecological wellbeing and fostering capacity to respond to disruptions and hazards in cities and urban regions.
3. Research Efforts to Study Urban Sustainability and Resilience in Practice
There are many different approaches and recommendations in the theoretical and practical literature on the analytic (“is”) and normative (“ought”) dimensions of urban sustainability and resilience. Therefore, rather than suggesting yet another framework, in this section we sketch a roadmap synthesizing fundamental components and questions defining existing, and potential, research on urban sustainability and resilience that can productively guide future research and practice.
3.1. Causal Relationships and Attributes
Diverse quantitative and qualitative methods have been devised to analyze a myriad of social, economic, technological, ecological, and governance processes of urban development. Yet these studies have not attempted to examine interactions between the SETEG domains comprehensively. Furthermore, examinations of these processes usually fall to explaining deficiencies in sustainability or resilience and to defining what combinations attributes accurately characterize these deficiencies in units of analysis ranging from segments of urban populations to whole cities, urban regions and countries (see Shen et al., and Suarez et al., this issue).
For example, socio-ecological systems approaches to urban sustainability focus on the dimensions and attributes explaining the long-term impacts cities have on their resource bases, ecosystem functions, and populations’ welfare. They apply indicators of (a) sources
of energy, water and other natural resources; (b) sinks
affecting such things such as the quality of water bodies, air pollution levels and GHG emissions, based on the ability of natural systems to absorb urban wastes and byproducts, within limits set by carrying capacity; (c) dynamics
of ecological support systems, e.g., climate regulation, flood protection; (d) socio-demographic characteristics
of urban communities, infrastructure, and aspects of the economy affecting sustainability and resilience; and (e) impacts
on human welfare [26
Scholars researching urban sustainability and resilience, as processes determined by a context specific combination (or lack) of capacities, focus on (dynamic) attributes of resources, assets and options urbanites draw upon to respond to disruptions and stresses they encounter (resilience), while pursuing their livelihoods, businesses, and urban planning and management goals (sustainability). This issue offers examples of efforts to capture the attributes defining these capacities. Romolini et al. (this issue) suggest a social-ecological framework (STEW-MAP) for examining and understanding urban stewardship networks in the cities of Baltimore, Chicago, Los Angeles, New York, San Juan, and Seattle. Their goal is to identify and examine relationships between these organizations and the ecological phenomena with which they interact. Building on Ostrom [23
], Schauppenlehner-Kloyber et al. (this issue) identify critical attributes defining governmental and nongovernmental actors capacities to govern the sustainability and resilience of urban commons in the Austrian city of Korneuburg. Key attributes are (a) well-defined boundaries around who participates and the spatial delimitation of the urban resources; (b) congruence among benefits, risks and costs for participants; (c) actors who have the right to co-design their own rules; (d) regular monitoring of actors and resource conditions; (e) graduated sanctions to maintain cohesion; (f) mediation and conflict-resolution mechanisms; (g) minimal recognition of participants rights by government; and (h) allocation of authority for adaptive governance at multiple, nested levels.
Other scholars have identified a series of political and economic factors determining institutional capacity for change in cities [75
]. Institutional capacity here refers to the broad pool of resources urban governmental, private, and nongovernmental actors can use to pursue both sustainability and resilience goals (e.g., reducing energy use or adapting to climate stresses). Scope and effectiveness of actions was found to be affected by these factors [41
Composition of the group—as defined by the multilevel actors and networks involved, and the mechanisms in place for actor engagement and participation
Legal frameworks in place to define responsibilities, decision making power, and planning mechanisms
Generation and transmission of information and different ways of knowing
Financial resources, decision-making power, and leadership.
Meerow and Stultz and Aldunce et al. (this issue) use a literature review and a participatory approach to identify attributes of urban resilience in theory and practice. While Aldunce et al., highlight the importance of co-production in turning abstract factors into concrete, context specific and socially relevant knowledge, Meerow and Stultz find that scholars and practitioners define urban resilience differently, with the latter using more engineering, steady-state approaches (Table 1
: Governance), which run the danger of focusing urban policy action on maintaining the status quo.
A different picture emerges from analyses focused on urban sustainability and resilience at the community level. For instance, McMillen et al. (this issue) analyze the broader sustainability implications of resilience attributes, such as place attachment, social cohesion and networks, and knowledge exchange and diversification. These are attributes of stewardship practices, defined as actions of caring for the environment “to enhance the quality of life for the greater public good”. Two stewardship practices, urban gardens, and the Living Memorials Project, in response to the losses due to the September 11 terrorist attacks in New York, provide a sense of place attachment and identity that can enhance urban communities’ empowerment and sense of agency.
For scholars using livelihoods approaches to research sustainability and resilience of urban households, stresses and hazards interact with historic patterns of socio-economic and institutional segregation, placing some urban populations in hazard-prone areas and endowing households with access to resources and options differently [77
]. Forces of socio-economic and socio-spatial segregation are conditioned by interactions between SETE
Without specifically naming them as such, scholars identify key SETE
G factors determining populations’ resilience or vulnerability (see Table 2
): (1) the characteristics of the stressors
or disruptions to which populations are exposed (e.g., magnitude, intensity and timing); (2) the set of multilevel capacities allowing populations to respond, and pursue their livelihoods; and (3) the responses
to and impacts
of the stressor(s) on populations’ wellbeing (e.g., their health; patterns of behavior, and functioning at home, school, or work). Capacities are determined by historically constructed social and institutional factors [79
Urban labor, land and housing markets;
Legacies of past political decisions around land use planning, infrastructures and services;
Mechanisms of social exclusion (e.g., through race and gender);
Actual or potential resources that are connected to possession of a durable network of social interactions;
How populations perceive networks (e.g., as caring and readily available, or aloof and unavailable) as well as how they use them to pursue their life and development goals and to respond to hazards;
Information and communication as access to useful information is a key resource that allows sustainable and adaptive performance [79
These last two attributes interrelate, as communication is a two-way transmission of meaningful information that creates shared meaning and a chance for community members to express needs and exchange views [72
3.2. Relationships between Attributes and Outcomes
In order to better understand the links between attributes of dimensions of urban development and sustainability and resilience, scholars and communities of practice have compared examples from local contexts to show how differences in relevant attributes may affect outcomes. A solid body of literature exists on the links between sustainability or resilience outcomes and a variety of attributes—from city size through socio-economics to multilevel governance and sustainability actions in cities (see Wu et al., this issue). This literature will be boosted by the framework for implementing Sustainable Development Goals (SDG), particularly SDG 11, which calls to “make cities and human settlements inclusive, safe, resilient and sustainable” [82
], as it is mostly concerned with the extent to which local governments have and will commit to sustainability and resilience principles in their planning practices [7
]. Scholars are already pointing to challenges of data availability to monitor SGD performance, in terms of issues such as indicators chosen, data sources, and level of temporal and spatial resolution [83
]. In seeking to understand the low levels of adoption of sustainability policies and actions by city officials, Svara et al [84
] identify a comprehensive set of explanatory factors. These factors include not only control variables (e.g., city density and population), but also forms of government, policy priorities, and community attributes such as age, income, education, home ownership and ethnicity (see also [40
A Pressure-State-Response conceptual model focuses on two main forces determining sustainability or resilience outcomes: the processes involving increasing pressure and the processes relieving that pressure [85
]. Blakie et al., (2004) the creators of this model, point to how disasters (an outcome ) are created by pressures, such as physical or biological hazards and the cumulative progression of vulnerability resulting from historic processes of socio-spatial differentiation; and to how disasters are also mediated by dynamic pressures such as governance structures. This approach, which has been used by the Organization for Economic Co-operation and Development (OECD) to measure urban sustainability over more than two decades, entails indicators of three dimensions: (i) stresses or disruptions such as financial turmoil and climate change; (ii) urban conditions such as quality of access to energy and water, ecosystem services, and human health; and (iii) capacities to respond including financial and technical resources, city expenditures and actions [88
In the current context of daunting social inequality worldwide [89
], key to creating a science that can engage with and inform actions to enhance sustainability and resilience across scales, will be understanding how urban households, ranging from poor to wealthy, vary in their capacities to create sustainability and resilience and knowledge of the processes creating this variability. Some scholars have combined qualitative and quantitative methods to analyze the relative influence of wealth and inequality on differentiated capacities to respond to climate stressors, within and across household classes in cities [79
]. They have found that under current climate conditions, high household vulnerability levels in cities are accounted for mainly by differences in indicators of wealth (e.g., land tenure, housing, stable income, infrastructure) and of capacity (e.g., education, reliance on community support). Urban development attributes of wealth and capacity are fundamental determinants of resilience across cities worldwide [78
]. Since this pattern of unequal access to resources and options could be aggravated in a future (warmer) world, scholarship clearly points to the urgency for capacity enhancing actions and policies to increase the resilience, particularly of vulnerable populations. Furthermore, research suggests profound transformations are necessary towards policies and actions addressing the structural drivers of social marginalization and exclusion in cities ([79
] and Fernandez et al., this issue).
3.3. Comparison and Classification
Several efforts have been made to compare and rank urban sustainability or resilience attributes, trends and actions within and across cities. The most common tool to do this is the use of indicators for an array of analytic and normative purposes: to improve scientific understandings and make comparisons; to capture multiple aspects of urban sustainability and resilience; to determine baseline conditions and measure trends; and to support decision making through monitoring and warning systems [88
]. Because urban sustainability and resilience are multivariate and multifaceted, a range of different methods can be used to characterize the relative importance of indicators. For instance, some scholars and practitioners have applied the three Es
approach (environment, economy, and equity) to create indicators of performance to guide actions seeking to achieve more sustainable pathways of urbanization (e.g., OECD and Shen et al. this issue). Others have grouped indicators into the three Es
to capture the sustainability initiatives pursued by city officials [72
]. In a similar vein, Suarez et al., (this issue) rank resilience across 50 Spanish cities using indicators of diversity, self-sufficiency and participation.
However, the use of indicators is often fraught with problems. In measuring urban sustainability and resilience, the choice of indicators depends on the theoretical approach used, which tends to shed light on some dimensions and omit others [94
]. In building indicators, scholars and communities of practice are guided not by what they should measure but by what they can, given data constraints, or what they want, given values and interpretations, hence, inevitably leaving out some key processes and interactions involved (See Suarez et al., this issue). Scholars have pointed to the need to critically and constructively embrace the following challenges: subjectivity and uncertainty in many processes involved in the selection and aggregation of indicators; the selection of indicators may not be sufficient to describe the dynamic and complex nature of urban sustainability and resilience; the weights assigned to each indicator; and the ranking of observation units into sustainability or resilience categories [79
]. Several procedures have been applied to address and embrace subjectivity and uncertainty. These often involve developing different methods of collaboration among researchers, stakeholders, and urban communities throughout the index construction process (e.g., the selection and weighting of indicators and the aggregation of indicators) [59
4. Transitioning to Urban Sustainability and Resilience: Agreements and Differences
While the environmental limits to development and urbanization are increasingly acknowledged internationally, nationally and locally, there is little agreement on how to transition to urban sustainability and resilience in practice, let alone how to move from incrementalism to transformation. For some, urban sustainability and resilience are technical problems that can be addressed through greater knowledge, innovation and technical expertise. Others (including us) see these challenges as opportunities to engage in co-production, to explore and address the underlying urban development drivers and causes of environmental change [2
] (e.g., Ziervogel et al. this issue). Moreover, we need an understanding of the social, economic, technological, environmental, and governance strategies and innovations needed to support efforts to navigate to sustainable and resilient futures. However, we also must acknowledge that the meanings and implications of sustainability and resilience are contested and ultimately emerge from deliberations among actors with unequal levels of power about the desirability of alternate futures, the necessary means of attaining them, and the tradeoffs that will be accepted along the way. As such, sustainability and resilience require innovative approaches to understanding the social dimensions of change [11
] and engaging science with society at large [101
Indeed, an increasing number of works within the literature acknowledge that the challenges of sustainability and resilience exceed the capability of traditional sustainability and resilience science and practice [100
]. Furthermore, both scholars and communities of practice agree on the need for iterative approaches to science co-production (see Aldunce et al.; Ziervogel et al.; and Schauppenlehner-Kloyber et al., this issue). However, deep differences remain along two main fronts. First, those framings that suggest the use of interdisciplinary methods and data to objectively examine or co-analyze the dynamic interactions and feedbacks between social and ecological domains, in order to identify the key dynamics of urban sustainability and resilience challenges [101
]. Second, those approaches that embrace the importance of social practices, subjectivity, values, and consciousness in defining, contesting, imagining and creating more sustainable urban worlds ([102
] and Ziervogel this issue). In this context, rather than resulting from actions derived from scientific or expert knowledge, urban sustainability and resilience can and need to emerge from dialogues about desirable urban futures, of which the science of interactions between social and ecological systems will play a necessary but not sufficient part. As such, these goals must be informed by an understanding of the social, economic, technological, and ecological constraints to change and of the implications of different courses of action [101
5. Concluding Remarks
Many papers in this Special Issue and the broader literature reviewed in this article, are driven by the conviction that climate change and other environmental challenges facing humanity not only offer reasons for concern, but also open many opportunities for contemplating, questioning, and changing our current unsustainable relationships with the environment, and with each other. Furthermore, they open opportunities to transform the ways we think about and relate to our increasingly urban world.
Some similar challenges of scope and scale exist among sustainability scholars. For instance, they tend to view the environment, through a frame of human wellbeing, with first concern for economy and society. Similarly, resilience tends to be related to a system’s capacity to adapt to stresses and disruptions, often with a lower level of priority for the viability of other interacting systems. While seeing cities as socio-ecological systems can certainly extend the scope of our understanding of urban sustainability and resilience, its analyses can become too broad and may lose relevance in studying (or addressing) on the ground realities. We suggest, therefore, that the definition of urban areas as socio-ecological systems be decomposed to five SETEG domains. These domains represent subsystems of the socio-ecological universe, whose interactions can be more easily understood. We have given some examples of how indicators can be used to assess the SETEG dimensions and interactions creating urban sustainability and resilience, and discussed some of the limitations of existing approaches to indicator selection and aggregation.
Currently, rather than gaining a profound transformation in the way we see the world, science and practice are caught between two incongruent views of urban sustainability and resilience. From one perspective, this world is mechanistic, linear, and deterministic, thus allowing for steady-state and bounce-back interpretations of sustainability and resilience. This view is very common among city officials, as might be expected based on their need to operationalize and show concrete results in time and space (and economics). This bias has been shown by Meerow and Stultz (this issue). In the opposing view, however, our urban world is dynamic, complex, adaptive, and multifaceted. A recognition of this complexity, however, must also include a recognition of sustainability and resilience as emergent and contested concepts that are continually reframed. In practice, this reframing sometimes follows the need to respond to operational realities, real or imagined.
While the concept of capacity is fundamental to linking the analytic with the normative dimensions of urban sustainability and resilience (the “is” with the “ought”), the distribution of capacity cannot be separated from the political and economic realms in which it operates. In this distribution, the resources and remit, with some urban actors having to maintain the status quo, are central to enduring (resilient) patterns of socio-spatial inequality (Fernandez et al., this issue). However, this type of resilience may ultimately be self-defeating (mal-adaptive). Yet, even within the context of social barriers, change does happen. Others have capabilities to promote and innovatively nurture the transform the potential of communities (e.g., the youth) to reconnect to “life-support systems, social cohesion, and agency” (Ziervogel et al., this issue).
Capacities also vary across scales, and the uneven distribution of capacity across scale leads to conflict and problems with definitions of sustainability and resilience. Development, adaptation, and lifestyle choices that benefit the powerful within a city often create costs for the less fortunate. At the heart of this conflict is the offloading, in time and space, of stressors and impacts to future generations and vulnerable populations and places. A political and economic spectrum of visibility is created within the SETEG, based on the dynamics of power, economics, space and time. Operating within this spectrum, urban actors may create an appearance of sustainability or resilience by offloading the effects of energy and water use, waste generation, and social and environmental disruptions and stressors in space and time (outside the visible spectrum). It is fundamental, therefore, to examine not only what urban sustainability and resilience mean, but for whom, where and when, sustainability and resilience will be operationalized.
For all its potential, community and city level engagement with urban sustainability and resilience is also faced with challenges. Some contributors to this issue explore the capacities with which urban actors have to interact, deliberate and collaborate to pursue diverse sustainability and resilience goals. Examples include co-developing master plans in Korneuburg, Austria; Fostering Communal Wellbeing in Bergrivier, South Africa; and Living Memorials Project in New York. Yet, no matter how promising these efforts are, they are also constrained by structural processes and dynamic pressures, such as sociodemographic shifts, enduring (or resilient) socio-spatial inequalities and the dynamics of power.
These processes and dynamic pressures are only beginning to be understood by a sustainability and resilience scholarship that has its roots in seventeenth century, empirical science. This science made possible the industrial revolution that unleashed our current environmental crises. It also led us, along relatively straight pathways, to the relationships urban areas have with the natural world. Creating sustainable and resilient urban relationships with the environment will entail a reimagining of those relationships. That reimagining will require that we improve our understanding of the dynamics of urban relationships with the environment across space and time. However, just as importantly, we must better understand our relationships with each other within and across domains of time, space, economics, and human organization.