The key role of cities in managing sustainability transitions is acknowledged in both policy and practice (Hölscher et al., 2019a; Hölscher et al., 2019b; Allen et al., 2023). With most of the global population living in cities, they play a catalytic role in social transformations (Ziervogel, 2019) and driving innovation (Marshall and Dolley, 2019). In general, sub-national or local level institutions are considered well-placed to reduce greenhouse gas emissions faster than national governments (Romero-Lankao et al., 2018). However, while cities and sub-national actors can be well-positioned to implement climate and sustainability-related policies, they are often constrained by and dependent on national regulation, legislation, and resources (Betsill and Bulkeley, 2007; Byrne et al., 2007; Granberg and Elander, 2007; Lundqvist and Biel, 2013; Coenen and Menkveld, 2013). Given these constraints, cities must increasingly innovate to overcome obstacles and achieve change (Romero-Lankao et al., 2018).

While many cities have joined transnational networks and worked in various ways to take climate action for years, one barrier to more effective action is the presence of silos, as they can lead to policy inconsistencies and sub-optimal outcomes (Oseland, 2019). Especially in the context of climate action and sustainable development, different forms of silos and fragmentations in policy and institutional arrangements add constraints. Since climate change and sustainable development are complex problems, not isolated to one sector or sphere, they need to be addressed in cooperation (Al-Zubi, 2016; Harris et al., 2010; Baleta et al., 2019). Yet, cross-disciplinary and cross-sectoral communication about common goals can be challenging because of competing priorities, division of responsibilities, and mandates, which would also require the involvement of various institutions, actors, and different levels and scales of governance (Elsässer et al., 2022; UNDESA, 2018; Breuer et al., 2019; Bruyninckx et al., 2012). Addressing silos is thus an important research and policy objective.

In this paper, we investigate the potential for bridging silos in the context of city-level climate action by looking at how the EU Cities Mission initiative aims to support cities in addressing silos. We define silos in broad terms, beyond institutional boundaries and structures created by mandates or issue-area specialization. A silo implies an inability or unwillingness to communicate across lines of differences (Bento et al., 2020). There exist several broad underlying causes of silos, e.g., bureaucratic politics, path dependencies, standard operating procedures, knowledge and resource constraints, different organizational cultures and political systems that decentralize and redistribute power (Van de Walle and Hammerschmid, 2011; Scott, 2020; de Waal et al., 2019; Göpfert et al., 2019). Literatures on sociological institutionalism and organizational culture, for example, describe how different organizational logics and structures can create silos that can hinder effective joint problem solving (Høiland and Klemsdal, 2022). Such silos can be internal to a bureaucracy when multiple units are involved, or they can exist between actors and levels of governance (Göpfert et al., 2019). In some contexts, however, silos can be beneficial, for example, when it comes to specialized governmental agencies providing public goods; thus, breaking them would hinder that work (Scott and Gong, 2021).

Given the challenges that this siloed governance poses for climate and sustainability action, there are ongoing calls in research and public discourse to break silos, bridge silos or even “teach silos to dance” to create holistic, systemic, and integrative approaches to solving complex problems (Birner et al., 2024; Niestroy and Meuleman, 2016). Breaking silos refers to breaking down siloed structures. Conversely, bridging silos allows for silos to exist while fostering cooperation to counter the negative consequences of silos. Meanwhile, “teaching silos how to dance” refers to making silos “more flexible, permeable, interactive and transparent” (Niestroy and Meuleman, 2016). In other words, the term emphasizes learning across silos, to become aware and flexible when it comes to coordination, collaboration and dialogue. In this sense, the concept is closer to bridging silos, as it emphasizes that certain silos are necessary to keep but work around. As bridging silos is a broader term for describing ways of addressing silos without breaking them to keep some of their beneficial outcomes, we elect to use the terminology of bridging silos in the remainder of the paper.

The aim of this paper is twofold; (1) To build an analytical framework to understand what bridging silos entails and how they can be bridged, and, (2) To assess the extent to which the EU Cities Mission initiative launched by the European Commission (EC) in 2021 and housed under the Horizon Europe proposes to bridge silos to accelerate decarbonization in cities by 2030. This initiative follows a previous approach launched by the EC, known as lighthouse initiatives¹, that highlighted common European interests and provided an umbrella for coordinated activities. The EU Cities Mission can be defined as a form of governance innovation to increase the abilities of cities to address complex societal challenges. Given that the EU Cities Mission is the latest iteration of long-standing initiatives to achieve sustainability transitions, it is important to critically examine its design, potential, and challenges. Thus, the focus of this paper is on the design of the EU Cities Mission, rather than on how this policy is currently being implemented at the city level. In other words, the analysis provides insights into the aims and objectives of the EU Cities Mission and, therefore, describes its potential rather than evaluates its effects.

The EU Cities Mission represents an interesting case for our study on bridging silos since it has a boundary-spanning nature by bringing actors together in governing toward the same goal (Janssen et al., 2023). While based on voluntary participation, it appears that the Cities Mission aspires to bridge both horizontal (across departments and stakeholders) and vertical (across governance levels) silos (Quitzau et al., 2022). More specifically, the EC includes the following principles in the initiative: “(a) a holistic approach fostering systemic innovation instead of the present silo-based and fragmented approach–leading to integrated planning, (b) a multi-level governance and (c) a deep and continuous collaboration with citizens and between all stakeholders” (European Commission, 2020, p. 14). As such, the EU Cities Mission could be considered a most likely case for silo bridging.

The mission approach as a governance approach aims to bring together actors across different sectors, disciplines, and governance scales to stimulate innovation to solve a societal problem (Mazzucato, 2018b). It has historically been employed in various contexts, typically characterized by having a purpose of reaching a clear goal, such as putting a man on the moon. Contemporary missions differ since they often aim to address broader societal challenges, such as health (Sampat, 2012), energy (Anadón, 2012), or climate (Shabb et al., 2022). This makes societal missions more complex than earlier missions since they entail a long-term commitment (Foray et al., 2012) and “are less clearly defined and must be co-defined by many stakeholders” (Mazzucato, 2018a). Thus, whether the EU Cities Mission can fulfil the potential of bridging silos is an open question.

This paper, therefore, contributes new insights into the EU Cities Mission by examining its potential to bridge silos to achieve climate neutrality, and it is structured as follows. The next section outlines our methods and describes the empirical material. Then, we present an overview of the literature looking at “silos” in climate and sustainability governance at the city or municipal level, and based on that, introduce a framework on silos and strategies to overcome them. Next, we apply the framework to investigate to what extent the EU Cities Mission Implementation Plan and the Climate Contract guidelines aim to bridge these silos. Finally, we conclude by drawing out the implications of our findings for the scholarly literature and practice.

This paper is based on two methodological steps: a literature review to build the analytical framework of different types and approaches to silos and a qualitative content analysis of EU Cities Mission documents. The literature review included two phases. In the first phase we conducted a search in Google Scholar using the words bridging/breaking organizational silos, bridging/breaking silos politics, bridging/breaking silos governance, silos interaction, silos coordination issues, and institutional barriers. We prioritized the most relevant results at the top of the list of the Google Scholar search and used titles and abstracts for the initial screening.

The aim of the initial scoping review was to identify the most prominent silos to inform our framework. Our aim was thus not to conduct a systematic literature review but target the most relevant literature for our framework development. Therefore, we found Google Scholar to be a useful search engine as it provides a wide array of academic and grey literature in its search engine and generates the most cited research. We looked for literature that had a local or city focus on understanding how silos function in and impact cities. We particularly focused on journals of planning, development, governance, and policy. We paid specific attention to research on sustainability, Sustainable Development Goals (SDGs), climate, environment, energy, and green transitions. Then, we followed Lecy and Beatty’s (2012) approach by using a constrained snowball sampling method based on the construction of the publication network obtained through citation referrals. As a result, we gathered 23 relevant articles for the review.

In the second phase, we received feedback on the initial literature review from stakeholders that are part of the research project’s advisory group, including municipal representatives and researchers, and consequently expanded the search terms to institutional barriers, bridging boundary objects, policy integration, coordination, and collaboration in combination with “municipality” and “sustainability” filters. After the second round, the literature review resulted in 44 relevant peer-reviewed articles, book chapters, and reports. While we primarily looked for studies that directly referenced silos, we took a broad view of silos and included multiple meanings, such as fragmentation, barriers, isolated or separated constellations, boundaries that divide, and other phenomena that hinder communication and cooperation. The final selection of articles included mainly European literature because of its relevance to our case. However, a few studies from other regions – (North America and Africa) were also included since they appeared in the literature review search, and EU Cities Mission includes some non-EU cities as well. Based on this database of 44 readings, we constructed the analytical framework as described in the next section.

For the second methodological step, the analytical framework guided the qualitative content analysis applied to the EU Cities Mission implementation plan and the guidelines for the Climate City Contract (CCC). The latter consists of three documents: an action plan, a commitments document, and an investment plan (see Table 1). These documents were chosen for the analysis because they provide a detailed overview of the Cities Mission approach and represent a description of its structure, process, and mechanisms of implementation, thus serving as a good source to understand its governance framework and potential to address silos.

The climate city contract resource pack provides tailor-made resources for cities to develop action plans. Thus, we expect the CCCs guidelines to elaborate more on the role of the local-level authorities and actors in the governance process. It is important to emphasize that our analysis examines how the EU Cities Mission would work by design, which can differ from practice. However, this analysis is also important because it can inform future policy designs. We searched these documents for themes identified by the developed framework and for the absence or presence of the description of silos and silos bridging strategies. As in the literature review, we took a broad view of silos beyond direct mentions of the phenomenon. Based on the results, we discuss which strategies for bridging silos are prioritized and the potential of the Cities Mission approach in bridging silos to achieve decarbonization.

The purpose of this literature review section is to describe where silos are found, what forms the silos take and the strategies to bridge such silos. These three structural elements will compose the analytical framework (section 4) that aims to explore whether the EU Cities Mission can fulfil the potential of bridging silos. It is important to highlight that some silos and strategies for bridging them overlap and/or reinforce each other. Therefore, it is sometimes challenging to establish analytically distinct demarcations.

This section presents the assessment of the EU implementation plan and the Climate City Contract (CCC) guidance documents by outlining how the EU Cities Mission discusses silos and strategies for bridging them. Since its launch, the EU Cities Mission has selected 112 cities (100 from the EU and 12 from countries associated with Horizon Europe) to encourage them to act as experimentation and innovation hubs and inspire other cities to become climate neutral. By providing the selected cities with tailor-made advice, opportunities for funding and financing, networking, and learning, the Cities Mission encourages cities to develop innovative climate solutions and governance and citizen engagement for achieving climate neutrality by 2030.² Below we present the results of the analysis of the documents listed in Table 1 in the methods section. In this section, silos and strategies are presented in the same order as they are described in the analytical framework section.

The results of this paper suggest that the EU Cities Mission represents an attempt to facilitate silo bridging as it takes a comprehensive wide overview of silos and aims to work across multiple levels of governance and sectors to address climate change, although with varying emphasis on different types of silos and strategies. Specifically, there is considerable emphasis on sectoral silos, whereby the studied EU Cities Mission documents emphasize the need to work across different initiatives/sectors to create a holistic approach toward climate neutrality. The need for multi-level governance is also discussed, and for buy-in from regional and national levels, although bridging of cross-governance silos between the local and national level governments are not discussed in detail. This may indicate a limitation of the EU’s ability to influence and dictate national-level politics.

Thus, in contemporary EU settings characterized by multi-level governance, the bridging of cross-governance silos via a top-down approach orchestrated by an EU policy is probably unlikely. However, potentially cross-governance silos could be overcome via a proxy by bridging cross-sectoral silos. As sectors, businesses, and governments are forced to collaborate to address climate change, by extension they are forced to talk across jurisdictions and levels of government as well. It is important to note that the EU Cities Mission encourages a creation of national platforms that support cities in their climate work, but it is unclear to what extent the political representatives are encouraged to participate in these platforms, signaling that the silos are more likely to be bridged on the operational or bureaucratic level, rather than political level.

Notably, cross-organizational silos are not mentioned in depth either and thus, silos internal to municipal organizations are not addressed in any significant way. While re-organization of local authorities may be the main priority for bridging policy and addressing siloed ways of working within local governments, it appears to represent a blind spot and shortcoming of the EU Cities Mission. However, this finding could be indicative of the nature of analyzed documents. Future studies could investigate individual cities’ CCC and how they refer to cross-organizational municipal silos.

While the CCC(A) mentioned the possibility and need of creating new organizational innovations in city governments and a Transition Team, it is unclear how these new arrangements could function and be successful when considering existing structures, how novel and different from existing architecture they can be, and what could be their added value. The lesser emphasis on cross-governance and cross-organizational silos may indicate the political sensitivities involved, i.e., the more structural issues that are not easily resolved by closer collaboration due to power imbalances and competing interests (Patterson et al., 2024). It is thus unclear whether and how the EU Cities Mission aims to bridge silos that may rely on political initiatives.

In terms of strategies for bridging silos, a key emphasis is on the Mission Platform (and its digital format) as a way of facilitating the creation of networks, synergies, and peer-to-peer learning. The platform can be used for potentially bridging knowledge and mental silos by sharing information, best practices, and allowing for collaborative learning. The platform also showcases possibilities of exploiting synergies with other EU-supported activities and policy initiatives. As such, it can be seen as a tool for supporting policy integration and coherence. However, from a critical point of view, the platform may be limited in its ability to provide hands-on enhanced collaborative learning and knowledge production. To work in practice, such processes typically need to be locally embedded and engage local stakeholders, for collaboration and learning to generate transformative change (Wolfram, 2016; Van Mierlo and Beers, 2020).

We also conclude that the EU Cities Mission approach aims to strengthen the creation of shared ideas and goals through the Climate City Contracts. As such, the approach offers an overarching framework for different actors to align around. However, the EU Cities Mission does not problematize how this alignment may occur in practice or discuss the possible challenges that may arise. Importantly, the Cities Mission requires cities to decarbonize faster than EU-level and member state climate targets, which points to potential coordination challenges between the different levels of governance. Our analysis finds more emphasis on the potential synergies rather than offering strategies that may be useful toward effectively addressing potential negotiations and trade-offs in driving faster decarbonization. This finding is in line with previous studies on the Cities Mission (Shabb and McCormick, 2023).

Furthermore, there is a lack of attention to how to encourage stronger and more ambitious leadership on climate change (Betsill and Bulkeley, 2007). The literature on bridging silos highlights the importance of leadership, both on its own and as a facilitator for other strategies (e.g., creating networks). While the EU Cities Mission has created a structure with key roles involving EU-level expertise, national networks, and city representatives, there is no clear strategy to encourage particular forms of leadership, and it is unclear how such leadership can be facilitated. Given that the EU Cities Mission is under Horizon Europe (a funding mechanism), this may be a problem as clear and ambitious political leadership of the European Commission is also key. For the EU Cities Mission to succeed, it may need more direct political attention. Regarding leadership on the city level, the CCC(I) highlights the role of municipalities in facilitating the creation of well-functioning markets and support systems for other public and private actors. However, limitations that cities experience in influencing policy (e.g., national regulatory frameworks) are not mentioned.

Will the EU Cities Mission be enough to address the key silos hindering cities to achieve decarbonization? We can conclude that there is an ambiguity inherent in the EU Cities Mission, namely the roll out of a centralized idea/ideal, i.e., endorsing a top-down mission approach, which has been critiqued as a prolongation of new public management ideals, while decentralizing the responsibilities and actions for creating acceptance of the idea and the implementation of it. Thus there is an apparent lack of focus on bridging cross-governance silos. The EU Cities Mission departs from the assumption that national and local level actors are supportive of this centralized idea and will seek to work toward a climate-neutral city by 2030, and perhaps just as importantly, have the resources and financing to do so.

However, there are reasons to question this fundamental assumption. For example, while the EU Cities Mission relies on political leadership being aligned between local and national levels, often local and national politics have different priorities. On the one hand, the EU Cities Mission can help cities overcome national-level politics and connect to partners and finance on the EU level. On the other hand, the lack of requirement of commitment by national-level leadership weakens the possibilities of the EU Cities Mission, as it relies on synergies with national action, funding and regulatory frameworks. While there are requirements of commitment by national actors, there are no mechanisms to hold them responsible and accountable. Yet, as this paper has demonstrated, the EU Cities Mission tries to address silos by promoting multi-level and cross-boundary governance, which is much needed to tackle complex societal challenges.

This paper provides a contribution to the fields of European climate policy and governance, with a focus on the adoption and implementation of the EU Cities Mission to bridge silos. It creates an understanding of existing silos in city climate action and the potential of governance innovations such as the EU Mission approach to bridge these. We show that pathways toward climate neutrality face barriers that include various silos. The EU Cities Mission can be viewed as a governance innovation to address and bridge these. Through the Mission Platform, climate city contracts and other measures, the EU Cities Mission aims to create new forms of cooperation, commitments, resources and resource allocation, and actions to achieve climate-neutral cities by 2030. Whether or not it achieves this aim will depend on many factors. Here, we have examined whether it has provided guidelines for bridging silos comprehensively. By conducting a literature review, we identified that silos are embedded in siloed structures at different levels (cross-governance, cross-institutional, cross-organizational, and cross-sectoral). Within these structures, silos can be found in the form of mandates and responsibilities, goals and policies, resources, and knowledge and mental silos. Strategies to bridge these silos include policy integration, institutional arrangements and collaborative processes, (political) leadership, and shared ideas and visions.

In our analysis of the EU Cities Mission documents, we noted a clear lack of emphasis on certain silos and strategies for bridging them. We noted an absence of emphasis on national responsibility for climate action and bridging the national and local level interaction as part of the EU Cities Mission. While national research institutions and government agency representatives are included in the Climate City Contracts, national governments have no political responsibility to work with cities to enable their climate work. The EU Cities Mission seems to assume that subnational, national and EU levels are aligned, without providing a mechanism to ensure it. A commitment by the national government to facilitate the work of cities, or at the very least a forum where representatives from the local, national and EU levels could meet to discuss climate action as part of the EU Cities Mission could have helped in bridging the key silos. Without such mechanisms in the EU Cities Mission, the work of cities risks being undermined.

In the presence of these shortcomings, what can the case of the EU Cities Mission tell us about whether and how silos in other settings could be overcome? Given that the EU Cities Mission represents a most likely case for silo bridging and yet fails to discuss and provide tools for addressing certain silos, the findings provide a sobering view on the chances of bridging silos more broadly. However, the framework developed here, and the findings provide a deepened understanding for addressing silos in the future. Particularly, by highlighting the different types of silos and the different levels that they can occur on provides a framework for actors to continuously examine the need for bridging silos and possible strategies to use to address these. Bridging silos should thus be understood as a reflexive and dynamic exercise that involves continuous learning and developing new ways of working that maintain democratic processes of pluralistic and multi-level decision-making.

This analysis has also demonstrated that the proposed framework has proven to be a useful tool for empirical analysis, which can be used by other researchers and for other governance innovations as well. Simultaneously, there are some areas in which the framework could be further developed. Stand-alone, the framework might suggest that all silos need to be bridged and does not distinguish between beneficial and hindering silos. As mentioned in the literature review, there is a distinction in some studies between bridging, breaking, and teaching silos to dance – knowing which silos are hindering progress and collaboration could help understanding which strategies are needed. In addition, the framework distinguishes structures and types of silos systematically, as well as strategies to bridge these, but it does not provide detail on how these are interlinked, nor indicates the iterative character of the work that is needed to bridge silos.

More empirical studies are necessary to learn about contextual factors that might shape silos and the potential impact of strategies on specific silos. There is also a need to address the context in which silos operate. While this study has provided a primarily ‘static’ snapshot of silos and where they exist, contextual factors impact the presence of them, and it is “important to recognize that missions are products of particular governance arrangements that evolve over time” (Janssen et al., 2021). Just as the governance arrangements change over time, so does the presence of silos and how they interact over the duration of the EU Cities Mission. Related to this, such empirical studies may also help to further develop the idea of teaching silos how to dance as a more nuanced approach to bridging silos. Such an approach could reflect on progress linked to the EU Cities Mission in terms of learning, flexibility and adaptability across silos. This paper provides a useful entry point for future studies on adopting a mission approach and bridging silos at different levels of climate policy and governance, within and beyond the EU Cities Mission.