While the C40 has come to claim a position of global leadership based on a demonstrated ability to generate coordinated action and collective effort, the description of the network presented in Chapter 1 signals that this has not always been the case. This chapter explores the early phase of the C40 (2005-2009) in which the network was characterized by uneven participation and an inability to engender network-wide engagement and coordination. Applying the theory of global urban governance fields brings to light the dynamics of competition and political contestation and links the observed lack of coordination to an inability to achieve convergence around a common identity. The Clinton Climate Initiative and the C40 Chair (occupied by the cities of London and Toronto) and Secretariat each sought to project divergent ideas with respect to how cities of the C40 should “do” global climate governance, yet neither was able to leverage the mechanism of recognition to effectively claim authority and give shape and substance to the governance field. As a result, the governance field remained fragmented and uncoordinated; split, as with so many other city-networks, into a small group of leading cities and a large group of laggards.

This chapter presents Sustainability Solution Spaces for Decision-Making (SSP) as an integrative method for assessing sustainability. The SSP represents the room to manoeuvre in the system at hand so that it can develop sustainably. The approach fulfils (1) systemic criteria; (2) normative criteria; and (3) procedural criteria. It provides a consistent set of targets and considers the systemic relations among the indicators representing the city-region. This gives the decision-makers concise guidelines for sustainable decisions and makes them aware of the associated trade-offs. SSP can be pursued following a participatory and an expert approach. Whereas the expert approach requires high quality of data, preferably either over time or over a large number of cities, the participatory approach is more flexible and can deal with qualitative data. That is, the expert approach is appropriate for comparing large sets of cities with each other, clustering and providing benchmarks for specific city types, and delivering general indications where policy development is required. The participatory approach might be particularly useful for assessing the impact of a specific project or analysing a specific sector, such as mobility or housing, in depth.

Ecologic sustainability assessments are of increasing importance in understanding the physical resource metabolism of urban systems. In Stockholm, the so-called Hammarby Model visualised important synergies in waste and energy flows in the Hammarby Sjöstad urban district and supported improved metabolic thinking. Following the success of this approach, the Eco-Cycle Model 2.0 for the Royal Seaport was developed in cooperation between KTH University and the City of Stockholm. The Eco-Cycle Model 2.0 can take account of more dimensions than the Hammarby Model, including overall and detailed descriptions of resource flows in a lifecycle perspective. Important starting points for the model were (1) global and local challenges concerning the use of resources, with specific relevance for urban development, (2) available models which visualise functions, resource flows, and resource synergies and (3) approaches to material, energy, and water accounting. The primary objective of the model is to show important connections and synergies between resource flows in a modern urban area. Secondary objectives that can be fulfilled in the long term are: to be a tool for the monitoring and follow-up of environmental objectives, to serve as a dynamic tool for the analysis of resource flows, and to contribute to improved urban planning.

Sustainability assessment aims to operationalise the popular but ambiguous concept of sustainability in the analysis of concrete problems and in decision-making situations. However, instead of being a strictly defined methodology, sustainability assessment is a field of science and practice that covers a range of possible tools and processes. To give an introduction to the topic, in this chapter we first place sustainability assessment in its societal and scientific context, and then proceed to discuss its definitions, characteristics, and current limitations based on a review of state-of-the-art literature. Furthermore, we propose a general framework of the dimensions of sustainability assessment, which makes a distinction between the assessment process itself and the broader contextual factors that influence the design of individual applications of sustainability assessment. The framework is meant to identify in a comprehensive manner the concepts, questions, and choices that a thorough design of a sustainability assessment will encounter.

This chapter engages with existing literature and case studies to examine current challenges and ways forward for the sustainability assessment of urban agriculture. It identifies current conceptualisations of urban agriculture, and sustainability assessment methods, and discusses them in the light of normative, systemic, and procedural dimensions of sustainability assessment. The diversity of urban agriculture and its presence in different urban contexts worldwide, represent challenges for sustainability assessment. This chapter shows that there is a paucity of assessment methods that are both specifically developed for urban agriculture and flexible enough to be applicable for different forms of urban agriculture in the Global North and South. Sustainability assessment of agriculture has usually focused on agriculture for market production in relatively stable rural contexts. However, urban agriculture poses challenges of diversity, multi-functionality, contested framings, and knowledge integration, which manifest more acutely in urban than in rural contexts, and which many existing sustainability assessment approaches and methods fail to address. The chapter discusses opportunities to move the practice of sustainability assessment of urban agriculture forward. These include the adoption of inter- and transdisciplinary research strategies, and a critical and reflexive approach to urban agriculture practices, power relations, social norms, and institutional conditions.

As an industrial revolution booms in Chile, the country’s air has been flooded by toxic emissions. Cities face the worst of the pollution, as factories are booming and urban centres are growing. Cars are one of the main contributors towards the accumulation of PM2.5. Sharing trips may help reduce the number of private and public vehicles on the road and thus reduce greenhouse gas emissions, travel time, and cost to individuals. In this study, I apply the concept of shareability networks to a survey of 113 591 trips taken in the city of Santiago in Chile, showing that with increasing but still relatively low passenger discomfort, cumulative trip length can be cut by 50 percent or more. I quantify the benefit of ride sharing in terms of traffic and emission reduction. I finally show that the ride-sharing potential is substantial, with nearly 100 percent of the trips shareable with current public transportation trip demand.

Sustainability as a key principle that guides the development of our societies requires fundamental transitions if we are to attain a more liveable planet. Concomitantly, the question of how to assess sustainability not only with respect to specific system states, but also regarding transition processes as a whole, has gained greater importance. In this chapter, we propose to extend established sustainability assessment practices with an approach informed by resilience thinking. In particular, we apply a systemic angle to develop three analytical perspectives which focus on the progress, the stability, as well as the adaptability of transition processes. These perspectives make it possible to reflect on the history, current state, and (potential) future development of the system in transition. We illustrate how these analytical perspectives can complement existing sustainability assessment approaches with regard to the description, interpretation, and evaluation of the transition process.

This chapter provides an insight into the role of systems science for sustainability assessment. In the first part, we present seven axioms that have been derived from system-theoretical perspectives and show their relevance for sustainability assessment. Following these axioms, we propose a way to structure and analyse systems following four system characteristics: (1) system boundary and interactions with the external environment; (2) purpose, goals, and associated decision-making drivers and criteria for the system; (3) system structure (subsystems, elements, and their interactions), dynamics, and emerging behaviour; and (4) system information, outcomes monitoring, and learning. These four characteristics were applied to study, first, the historical development of the energy system analysis and, second, an Australian urban systems-transformation initiative. The systems-analysis framework presented provides a good basis for putting the elements of a system analysis into their broader context, and designing purposeful interventions. Especially for more transformational change, the alignment of stakeholder values, institutional arrangements, and available knowledge become key leverage points.