Urbanization and urban areas are profoundly altering the relationship between society and the environment, and affecting cities’ sustainability and resilience in complex ways at alarming rates. Over the last decades, sustainability and resilience have become key concepts aimed at understanding existing urban dynamics and responding to the challenges of creating livable urban futures. Sustainability and resilience have also moved and are now core analytic and normative concepts for many scholars, transnational networks and urban communities of practice. Yet, even with this elevated scholarly attention, strategies for bridging between research and practice remain elusive, and efforts to understand and affect change towards more sustainable and resilient urban centers have often fallen short. This paper seeks to synthesize, from this issue’s papers and other strands of literature, the knowledge, theory and practice of urban sustainability and resilience. Specifically, we focus on what capacities urban actors draw on to create sustainability and resilience and how different definitions of these concepts intersect, complement, or contradict each other. We then examine the implications of those intersections and differences in the efforts by urban actors to enhance the capacity to change unsustainable trajectories and transform themselves, their communities, and their cities toward sustainable and resilient relationships with the environment.

Urban centres play a crucial role in managing global carbon emissions (mitigation) and reducing vulnerability to climate change (adaptation). This paper describes some of the mitigation and adaptation entry points and challenges for city-relevant planning and policy-making posed by the processes defining urban greenhouse gas emissions, vulnerabilities and adaptive capacities. It finds that although many cities are already responding to the climate challenge, existing initiatives are fragmented and a piecemeal rather than a strategic approach is very common. Frequently mitigation and adaptation responses do not address many of the key drivers and determinants involved (e.g. consumption patterns and equity issues determining differentiated access to the determinants of adaptive capacity), nor do they fit with the issues they are intended to address. This is so because climate responses and the issues they are intended to address are multi-scale in nature because most of the processes involved operate at multiple sectoral, temporal and spatial levels. In the face of the complexity of the interconnected processes involved in the relationships between cities and climate change, it is not surprising that local authorities tend to move towards rhetoric rather than meaningful responses.

Cities are both significant emitters of carbon dioxide and centres of innovations that may contribute to de-carbonizing our societies. More voices claim therefore that local authorities should be included in efforts to mitigate climate change. However, few studies have analysed how local authorities manage carbon and climate in urban areas in middle- and low-income countries. Yet, the institutional settings and governance structures of such cities are different from those prevailing in cities of wealthy countries. This paper aims to fill this gap by exploring: (a) whether and—if so—how local authorities in Mexico City actually ‘manage’ carbon emissions; (b) how the city's evolving governance structures function and whether they ‘fit’ with the problem they address; and (c) how institutional capacity constrains authorities' management efforts. The paper suggests that policy networks and research groups have been critical in launching a climate agenda. Nevertheless, this has not been enough to push effective policies. Policymaking has been constrained by two sets of institutional factors: the problem of fit and a lack of institutional capacity.

Independent lines of research on urbanization, urban areas, and carbon have advanced our understanding of some of the processes through which energy and land uses affect carbon. This synthesis integrates some of these diverse viewpoints as a first step toward a coproduced, integrated framework for understanding urbanization, urban areas, and their relationships to carbon. It suggests the need for approaches that complement and combine the plethora of existing insights into interdisciplinary explorations of how different urbanization processes, and socio‐ecological and technological components of urban areas, affect the spatial and temporal patterns of carbon emissions, differentially over time and within and across cities. It also calls for a more holistic approach to examining the carbon implications of urbanization and urban areas, based not only on demographics or income but also on other interconnected features of urban development pathways such as urban form, economic function, economic‐growth policies, and other governance arrangements. It points to a wide array of uncertainties around the urbanization processes, their interactions with urban socio‐institutional and built environment systems, and how these impact the exchange of carbon flows within and outside urban areas. We must also understand in turn how carbon feedbacks, including carbon impacts and potential impacts of climate change, can affect urbanization processes. Finally, the paper explores options, barriers, and limits to transitioning cities to low‐carbon trajectories, and suggests the development of an end‐to‐end, coproduced and integrated scientific understanding that can more effectively inform the navigation of transitional journeys and the avoidance of obstacles along the way.

This paper describes the risks that Mexico City faces from flooding and water scarcity, how these risks developed over time and how climate change will affect them. It begins by discussing the climatic and hydrological conditions that explain the abundance of water resources and the droughts and floods that have affected the city and its surrounds for centuries. It then presents the water-relevant implications of climate change for the city and considers who is likely to be most impacted. Floods, droughts and other water-relevant hazards are the result not only of “nature” (and now of human-induced climate change) but also of past and present socio-environmental changes. This helps explain why Mexico City’s population, infrastructure and systems are less able to cope with climate change.