Assessing progress in sustainable climate change adaptation in cities using a novel evidence-based knowledge synthesis method: Case study Hamburg, Germany

With global greenhouse gas emissions still rising and global mean surface temperatures continuing to reach record highs, climate change adaptation (CCA) progress is more important than ever. Cities and urban areas in particular, are both major contributors to climate change and important sites for innovation and frontrunners of adaptation action. The commitment set out in the Paris Agreement to “review the adequacy and effectiveness of adaptation” (Article 7, para. 14c) has catalyzed a focus on tools measuring and evaluating adaptation progress. However, quantitative metrics for measuring success have been criticized for lacking a common understanding of adaptation effectiveness, failing to consider local contexts, inadequately capturing the complex, multifaceted nature of adaptation, and lacking a reflection on whose values and views guides these assessments. For example, existing global stocktaking of human adaptation-related responses to climate change, including the United Nations Global Stocktake under the Paris Agreement and the Global Adaptation Mapping Initiative’s Global Stocktake, provides an overview of documented adaptation but does not capture the underlying societal dynamics. To address this gap, we propose a novel qualitative approach based on a comprehensive analysis of the drivers and enabling conditions for sustainable CCA in cities reported in the scientific literature: the Sustainable Adaptation Plausibility Framework. By explicitly focusing on the breadth of societal processes and actors, our novel approach attempts to do justice to the complexity of adaptation. To “measure” adaptation progress and success we explicitly link adaptation with the sustainability concept. Recognizing that adaptation is not just an “outcome”, our differentiated analysis of processes and their interaction does not center on what is reported in articles, but rather on what cities (including urban society) actually do, integrating a diversity of scientific and non-scientific sources.

Our novel framework draws on an in-depth analysis of social processes that act as drivers toward or away from a given sustainable urban CCA scenario. Based on the literature and our own expert elicitation, we have identified a set of drivers that represent relevant existing and emergent social processes that drive sustainable CCA in cities. As a proof of concept, we assess sustainable CCA by 2050 as one politically relevant scenario using the city of Hamburg, Germany, as a case study. Delving into rich empirical data provided by the case study, we analysed the past, present, and emerging dynamics of these societal processes, as well as their social, political, economic and environmental context conditions that could enable or constrain them in the future. Six of these drivers have been analysed in depth for Hamburg: CCA-related regulation, Local CCA governance, Shifts in mindsets, Urban CCA activism, CCA litigation. The results will be shown in the presentation.

Through an interdisciplinary approach, we aim to build a better understanding of the social, psychological, cultural, and political dimensions of sustainable CCA in cities. This study demonstrates our framework’s potential as a novel evidence-based knowledge synthesis method for tracking (un)sustainable pathways of urban adaptation analyzing societal processes, in addition to merely reporting adaptation measures.