Urban Shrinkage, Degrowth, and Sustainability: An Updated Research Agenda

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Introduction
Urban shrinkage has affected an increasing amount of cities and towns in the past decades and has attracted the interest of urban studies and planning scholars as well as urban policy-makers.Urban shrinkage can have several causes, but most often it is rooted in a structural economic crisis, resulting in population decline, vacant and decaying buildings, and underused infrastructure.While some cities manage to return to a growth path after shrinkage, most may have to prepare for further shrinkage or stabilization instead.Generally, the urban shrinkage discourse advocates a departure from the dominant growth paradigm, and policy advice focuses on adapting to shrinkage rather than a forced attempt to return to growth (e.g., Hospers, 2014;Mallach et al., 2017;Wiechmann & Bontje, 2015).However, this is easier said than done: Both academics and policy-makers still struggle with how to revitalize shrinking cities sustainably in the absence of growth (Liu, 2020).
In the early 21st century, the "limits to growth" debate of the 1970s revived under the radical header of "degrowth."To achieve a sustainable society, the degrowth movement advocates for fundamental changes in economic and social systems to drastically reduce resource and energy use.Instead, societies should prioritize social and ecological well-being (D'Alisa et al., 2014;Kallis et al., 2018).Until recently, degrowth thinking remained rather abstract, but in the past few years interest in applying degrowth principles to the urban level has greatly increased (e.g., Kaika et al., 2023;Savini et al., 2022;Xue & Kębłowski, 2022).As such, it aims to provide a radical alternative to the mainstream "green growth" approach to sustainable urban development.
The latter does not fundamentally question the current growth-based production and consumption systems, but rather attempts to minimize their negative impacts on sustainability (Jacobs, 2013).
Shrinking cities and degrowth thinking share their parting from the dominant growth paradigm and seem to have much to offer to each other.Could degrowth be an inspiring and guiding paradigm for the sustainable development of shrinking cities? Could shrinking cities be suitable testing grounds to apply degrowth's radical sustainability principles in practice?These and other questions regarding the connections between urban shrinkage, degrowth, and sustainability have hardly been addressed in the scientific literature thus far.This thematic issue therefore aimed to bring together novel empirical contributions, taking stock of first attempts to connect degrowth to urban shrinkage, exploring in how far this potential unfolds in practice and what obstacles these attempts face, with a focus on the field of urban planning.

Connections Between Urban Shrinkage and Degrowth
Judging from the contributions to this thematic issue, explicit adoption by shrinking cities of a degrowth perspective on sustainable urban development is still rare in Europe and North America.The only empirical study of such a case is the article by Brokow-Loga and Eckardt (2024).This rich case study of a small East German town helps to discern a variety of factors that play a role in this respect.Enablers are a long-term participatory process, attention for local social problems, and a public-civic partnership, in this case with an important activating role for the local Transition Towns group.Barriers to more than small incremental measures are the limited financial resources of shrinking cities, and the limited operating space for cities within the wider growth-oriented system.A relatively new barrier concerns the rise of right-wing populists and climate change-denying actors, which is particularly strong in shrinking cities with their socio-economic problems and disappointed "left-behind" elderly voters.
More obstacles to adopting a degrowth perspective in urban planning were identified by Lamker and Terfrüchte (2024) in their study of planning instruments in North Rhine-Westphalia (Germany), from the state, down to the regional and local level.They found that pro-growth premises are deeply nested within these planning instruments, which, in addition to reliance on past developments or the status quo, makes achieving post-growth ambitions very difficult.
The analysis of comprehensive plans of 18 cities in the Rust Belt in the US by Marjanović et al. (2024) makes clear that, despite the advice of academics, most shrinking cities continue to pursue growth.In cities explicitly aiming for sustainable development, this is often labeled as "smart growth," which includes, for example, green building technologies.A closer look at these plans reveals, however, that the situation is not all black-and-white.Cities that aim for growth as well as cities that have adopted a degrowth or rather "smart decline" strategy often have a differentiated strategy for different parts of the city, with a growth strategy for the central district and a "smart decline" strategy for peripheral districts.
This differentiated urban planning approach to the socio-spatial variation often present in shrinking cities was also evident in the cases studied by Hermans et al. (2024) in the shrinking urban region of Parkstad in the Netherlands.Their question whether shrinking cities can serve as testing grounds for urban degrowth practices could therefore not be answered unconditionally, as this depended on the specific urban planning and development context which differed strongly between the two studied districts.
Whereas in the case of Parkstad the intentions of urban planners were sincere and their "smart shrinkage" or degrowth-like approach yielded positive social and ecological outcomes, this was not the case in three districts in Genoa, Italy.The case study by Kërçuku (2024) showed that here "smart shrinkage" and degrowth were only superficial statements, not really "internalised in the development models proposed by public administration" (p.15), and that the outcomes of the three "controlled shrinking" projects were perceived very negatively by the residents.
Finally, the case study of Coimbra (Portugal) by Ferreira et al. (2024) shows that the connection between urban shrinkage and degrowth can be very different than commonly assumed.In their case, demographic shrinkage was not caused by economic decline, but by a perverse form of economic growth associated with speculation in the housing sector.To remedy this situation, they advocate to incorporate degrowth thinking into urban planning.

Dialogues Between the Contributions
Analyzing the eight contributions for this thematic issue, we identified four dialogues, each of them spanning across at least two contributions.These dialogues advance and nuance our understanding of the connections between urban shrinkage, degrowth, and sustainability.
One of these dialogues revolves around the question whether and in how far degrowth planning is actually happening.Has degrowth inspired new forms of urban planning, and has this translated into new policy goals?Marjanović et al. (2024) provide pessimistic empirical evidence of a survey of planning documents of 18 shrinking cities in the US Rust Belt.They find that urban shrinkage is accepted, but strategies remain focusing on growth.In their study of two urban greening initiatives with contrasting results in Parkstad, Hermans et al. (2024) provide the more optimistic account that "degrowth practices" in urban planning can be identified and conceptualized as experiments to foster joint learning on new urban planning approaches that make use of urban shrinkage to achieve an increase in social and environmental welfare.According to these authors, degrowth practices should be made more explicit as experiments to explore whether and how degrowth planning is fertile.
The second dialogue in this thematic issue concerns the role of a master plan or national policy in steering for a strategic response to shrinkage.In their analysis of strategic land use planning in a shrinking city region in Finland, Oittinen and Mäntysalo (2024) find that strategic land use planning is a feasible tool for managing shrinkage, as long as a master plan remains flexible.Specifically, in the case studied, it appeared that growth was not essential to implement the master plan.Bontje (2024), on the other hand, looks at national-level policy for shrinking regions in the Netherlands.However, flexibility appeared to be a problematic issue here, because the national policy changed over the years, affected by national government reorganization processes.As a result, the attention for shrinking regions has substantially diminished.
A third dialogue revolves around the question whether and how urban planning can steer for degrowth by looking concretely at the question of land consumption and population loss.Lamker and Terfrüchte (2024) analyze the premises of two key planning instruments in Germany to find out whether they can help in bringing land consumption to a sustainable net-zero level.They conclude that the premises of both instruments support the continuation of pro-growth practices, and that we might face a lock-in due to the way in which planning instruments have internalized growth as a goal.Ferreira et al. ( 2024) confirm their hypothesis that the city of Coimbra in Portugal experiences population loss due to urban policies that promote economic growth through housing speculation.Paradoxically, urban planning seems to have the capacity to steer for population decline through incentivizing economic growth.
The fourth dialogue addresses the connections between shrinkage, degrowth, and democracy.Here, Brokow-Loga and Eckardt (2024) examine the links between shrinkage processes, a local degrowth agenda, and the consequences of eroding democracy, focusing on a local process of arriving at a degrowth agenda in the small Eastern German town of Zella-Mehlis.They conclude that the process is ambivalent, because economic shrinkage and population decline have opened the doors for authoritarian politics.Nevertheless, long-term participatory processes within a public-civic partnership can challenge path dependencies and open new, degrowth-inspired perspectives.Looking at three controlled-shrinking projects in urban renewal areas of Genoa, Italy, Kërçuku (2024) finds that they still adhere to a logic of growth and neglect social implications.What was presented as "smart shrinkage" by planners was widely experienced as removal and loss by local residents.The "smart shrinkage" discourse was only deployed superficially by the public administration, without delivering on the participatory promises, ultimately leading to projects that "shrink" the rights of the local population.

An Updated Research Agenda
In the call for papers for this thematic issue, we listed a number of key questions concerning the connections between urban shrinkage, degrowth, and sustainability in urban planning.The contributions to this thematic issue helped to answer some and to make others more specific, resulting in an updated agenda for this area of research.The attention for degrowth and its application in urban planning and development has continued to grow strongly after the publication of our call for papers in 2021.We therefore expect that more case studies have become available as an empirical basis for answering questions regarding the adoption of degrowth-based planning approaches and practices by shrinking cities.We conclude with six questions that we consider most urgent and topical: To what extent are degrowth-based approaches adopted in urban planning by shrinking cities? Are these approaches comprehensive or differentiated per district and combined with "green growth"-based approaches?

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In what way does the rise of populist right-wing political parties affect the adoption of degrowth-based approaches by shrinking cities? 3. What is the role of non-governmental, civic parties in the adoption of degrowth-based approaches by shrinking cities? 4. What can be learned from shrinking cities that have adopted degrowth-based approaches, with respect to dealing with pro-growth obstacles, inter alia in planning instruments and multi-scalar governance systems? 5. To what extent do applications of degrowth-based approaches by shrinking cities deliver positive socially and environmentally sustainable outcomes and impacts? 6.What can be learned from current degrowth-like urban practices in shrinking cities concerning their wider feasibility and uptake in urban planning?To what extent can or do these practices also inspire new directions and ideas in urban degrowth-thinking?Marjanović, M., Better, M. S., Lero, N., & Nedović-Budić, Z. (2024).Can acceptance of urban shrinkage shift planning strategies of shrinking cities from growth to de-growth?Urban Planning, 9, Article 6904.Oittinen, J., & Mäntysalo, R. (2024).Enabling multiple outcomes: Strategic spatial planning in a shrinking city-region.Urban Planning, 9, Article 7694.Savini, F., Ferreira, A., & von Schönfeld, K. C. (Eds.).(2022).Post-growth planning: Cities beyond the market economy.Routledge.Wiechmann, T., & Bontje, M. (2015).Responding to tough times: Policies and planning strategies in shrinking cities.European Planning Studies, 23(1), 1-11.Xue, J., & Kębłowski, W. (2022).Spatialising degrowth, degrowing urban planning.Local Environment, 27(4), 397-403.