2.1 Insight 1: migration is a force for sustainable development

Migration has the potential to contribute to sustainable development through the benefits it brings to cities and the people that live within them. It is thus of critical consideration for cities striving to reach the SDGs. Typically, when migration is considered as positive for destinations, it is framed from a utilitarian perspective in terms of economic and demographic benefits, with migrants filling labor shortages and covering social security gaps. For example, migration is recognized as vital to economic progress for countries at all levels of income (World Bank, 2023). However, economic growth alone does not translate to sustainable development which is about enhancing well-being in ways that more equitably meet the needs of present and future generations (Clark & Harley, Reference Clark and Harley2020).

Migration, though, also holds the potential to improve aspects of well-being. For example, people move to cities specifically to improve their material well-being, pursuing economic and educational opportunities (Gavonel et al., Reference Gavonel, Adger, Safra de Campos, Boyd, Carr, Fábos, Fransen, Jolivet, Zickgraf, Codjoe, Abu and Siddiqui2021). Other migrants move to cities to provide care, bringing caregiving practices and values from their places of origin that enhance receivers' caring experiences (Datta et al., Reference Datta, McIlwaine, Evans, Herbert, May and Wills2010). Thus, migration feed into progress toward Goal 3: Good Health and Well-being but also Goal 1: No Poverty, Goal 10: Equality, and Goal 4: Education. At the same time, while migration to urban areas often improves material well-being, survey data from developing countries suggest that subjective well-being does not always align with these gains (Szaboova et al., Reference Szaboova, Safra de Campos, Adger, Abu, Codjoe, Franco Gavonel, Das, Siddiqui, Rocky and Hazra2022). Migrants in both the Global South and North frequently report social exclusion due to isolation and discrimination (El Khouri, Reference El Khoury2024; Fozdar & Torezani, Reference Fozdar and Torezani2008; Jones, Reference Jones2014). The success of migration for improving individual-level wellbeing will thus depend on different individual trajectories and other factors as we discuss in insights 3–6.

Migration as a force for sustainable development is not only significant at the individual level. As Castles (Reference Castles2010) argues, migration influences economic, social, and cultural dynamics in both origin and destination areas making it a significant factor in social transformations. In the context of sustainable development, migration facilitates flows of ideas, knowledge, and skills that can promote innovation necessary for the achievement of the SDGs. This could for example manifest as everyday practices of using and conserving resources, as we elaborate on in Insight 2, and be an important contributor to Goal 12: Responsible Consumption and Production. Thus, whilst migration to cities has raised concerns about increasing unsustainable resource consumption, migration can also facilitate flows of practices and knowledge about sustainability that may hold new solutions to those very challenges.

Certainly, the overall effects of migration on destination areas depend on the size, composition, and nature of migration flows; the specific context from which migrants are drawn, and the timing of migration (Gavonel et al., Reference Gavonel, Adger, Safra de Campos, Boyd, Carr, Fábos, Fransen, Jolivet, Zickgraf, Codjoe, Abu and Siddiqui2021). This must be considered in any assessment of the relative impacts of migration on destination areas, since migrants may also come from countries of higher consumption than the destination. Nonetheless, as we argue here, cities that incorporate an understanding of these aspects of mobility in their planning will likely contribute more successfully to sustainable development.

2.2 Insight 2: migrants are sustainability actors

Transformative pathways toward sustainability call for the participation of all groups of society and require drawing on diverse knowledges (Scoones et al., Reference Scoones, Stirling, Abrol, Atela, Charli-Joseph, Eakin, Ely, Olsson, Pereira, Priya, van Zwanenberg and Yang2020). Current discourses risk devaluing migrants' contributions to sustainability by omission but also by misconception: studies from across the Global North and South show that when migrants are considered within sustainability thinking, it is often assumed that they interact with sustainability in negative ways, for example, through placing demand on public services, disrupting social cohesion, increasing crime rates, or as not understanding enough about sustainability (Fry et al., Reference Fry, Boyd, Connaughton, Adger, Gavonel, Zickgraf, Fransen, Jolivet, Fábos and Carr2024; Siddiqui et al., Reference Siddiqui, Bhuiyan, Kniveton, Black, Islam, Martin, Bhagat and Rajan2017). This risks misrepresenting behaviors, values, and agency of increasingly diverse urban populations who have migrated from other parts of the world or even from other areas within the same country.

To uncover the multitude of ways in which migrants are (positive) sustainability actors, we draw from work on ‘actually existing sustainabilities’ which illuminates actions that, while not explicitly linked to SDGs, possess the capacity to fulfill them (Krueger & Agyeman, Reference Krueger and Agyeman2005), including for example unintentional everyday habits informed by cultural norms and values in areas of origin.

Head et al. (Reference Head, Klocker, Dun, Waitt, Goodall, Aguirre-Bielschowsky, Gopal, Kerr, Nowroozipour, Spaven and Toole2021) show that ethnic minority migrants living in Australia wish to continue food growing practices based on experiences and cultural norms of small-scale farming in the countries that they come from. Recent evidence from Accra, Ghana shows that sustainability practices established before migration are predictors of current practices including proactive recycling, conservation activities, and choice of mode of transportation (Abu et al., Reference Abu, Codjoe, Adger, Fransen, Jolivet, Ricardo, Franco Gavonel, Agyei-Asabere, Fabos and Zickgraf2024), critical to achieve Goal 12. Evidence from Brussels further demonstrates that migrants apply pressure to local governments to improve their sustainability practices and programs, for example, by requesting more cycling paths, community gardens, and green spaces based on the comparisons they make with their place(s) of origin or previous residence (Zickgraf et al., Reference Zickgraf, Jolivet, Fry, Boyd and Fábos2024), feeding into progress toward Goal 11.

Migrants' sustainability practices, in their diversity, thus bring specific contributions to sustainability because they build on experiences in the places people migrate from, including cultural norms, habits, and values (Head et al., Reference Head, Klocker, Dun, Waitt, Goodall, Aguirre-Bielschowsky, Gopal, Kerr, Nowroozipour, Spaven and Toole2021), that have transformative potential in the places that they move to. In this sense, sustainability practices are not just individual behaviors but are immersed in multiple places, materials, and infrastructures that are part of everyday life (Head et al., Reference Head, Klocker, Dun, Waitt, Goodall, Aguirre-Bielschowsky, Gopal, Kerr, Nowroozipour, Spaven and Toole2021). Transformative approaches to sustainability would come about valuing and better understanding the knowledge, skills, and values brought by migrants to destinations.

3.1 Insight 3: cities should embrace and enable migrant voices

The transformative potential of migration and migrants is undermined by policy processes that narrowly frame migrants or ignore them entirely. For example, in Amsterdam, sustainability programs tend to narrowly target migrants through job schemes and language courses (MISTY, 2021). In Bangladesh, policy discourses frame migrants as problematic causes of insecurity and thus exclude them from policy processes (Siddiqui et al., Reference Siddiqui, Szaboova, Adger, Safra de Campos, Bhuiyan and Billah2021). Restricting the access of city residents of migrant backgrounds to spaces of sustainable planning is against the best interests of sustainability transformations.

For cities to fully reap the benefits of a rich and diverse population, officials should focus on fostering the ‘agency, values and capacities necessary to manage uncertainty, act collectively, identify and enact pathways to desired futures’ (Scoones et al., Reference Scoones, Stirling, Abrol, Atela, Charli-Joseph, Eakin, Ely, Olsson, Pereira, Priya, van Zwanenberg and Yang2020). Supporting migrants' participation in local democracy through advisory boards, encouraging entrepreneurship, or supporting involvement in sustainability initiatives like urban gardening were identified by city policymakers in Europe as important action points (Zickgraf et al., Reference Zickgraf, Jolivet, Fry, Boyd and Fábos2024). In Chattogram, Bangladesh experiments in deliberative democracy for urban planning have proven to be successful in integrating perspectives of new migrants of all genders, age groups, abilities, and residential locations to find new solutions to urban precarity. Voices articulated by new migrants are incorporated into the National Action Plan on climate-induced internal displacement, 2022–2042 (GoB 2022a).

City actions that enable and embrace migrants' voices ensure a more inclusive sustainable future that reflects all urban residents. Further, they support progress toward several SDGs including 16: Peace, Justice, and Strong Institutions (Target 16.7: ensure responsive, inclusive, participatory, and representative decision-making at all levels and Target 16.B: promote and enforce non-discriminatory laws and policies for sustainable development) and 11 (Target 11.3: enhance inclusive and sustainable urbanization and capacity for participatory, integrated, and sustainable human settlement planning and management in all countries).

3.2 Insight 4: reducing structural inequalities facilitates sustainable development

Embracing migrant voices must be accompanied by structural change. Many cities are characterized by precarity and inequality undermining social processes that would enable migrants to act on sustainability (Abu et al., Reference Abu, Codjoe, Adger, Fransen, Jolivet, Ricardo, Franco Gavonel, Agyei-Asabere, Fabos and Zickgraf2024; Adger et al., Reference Adger, Safra de Campos, Siddiqui and Szaboova2020; Jolivet et al., Reference Jolivet, Fransen, Adger, Fábos, Abu, Allen, Boyd, Carr, Codjoe, Gavonel, Gemenne, Rocky, Lantz, Maculule, de Campos, Siddiqui and Zickgraf2023; O'Dell, Fransen & Jolivet, Reference O'Dell, Fransen and Jolivet2023). In Accra, for example, migrants are exposed to social, economic, and environmental conditions, including poor infrastructure, that drive them into unsustainable practices to survive (Abu et al., Reference Abu, Codjoe, Adger, Fransen, Jolivet, Ricardo, Franco Gavonel, Agyei-Asabere, Fabos and Zickgraf2024).

While not all migrants or newcomers to a city are disadvantaged, addressing sources and drivers of precarity, cumulative deprivation, urban poverty, and social exclusion among marginalized migrant populations in urban spaces is taking a step to make cities sustainable for all (Abu et al., Reference Abu, Codjoe, Adger, Fransen, Jolivet, Ricardo, Franco Gavonel, Agyei-Asabere, Fabos and Zickgraf2024; Siddiqui et al., Reference Siddiqui, Szaboova, Adger, Safra de Campos, Bhuiyan and Billah2021). For example, targeted interventions to support secure employment and increase accessibility to social security programs were identified as important initiatives to foster resilience of Amsterdam residents with migration backgrounds during the Covid-19 pandemic (O'Dell et al., Reference O'Dell, Fransen and Jolivet2023).

For cities with diverse migrant populations, it may be preferable to employ an intersectional approach rather than assuming one label for all migrants or ‘migrant-specific’ interventions (Zickgraf et al., Reference Zickgraf, Jolivet, Fry, Boyd and Fábos2024). The 2021 Environmental Justice Policy in Worcester, US could serve as inspiration for other cities reinforcing that ‘all communities must have a strong voice in environmental decision-making regardless of race, colour, national origin, income, or language proficiency’. This is an effective way of addressing sources of disadvantage amongst diverse migrant groups. These measures are also likely to have cumulative effects on feeding into progress toward SDG 1: No Poverty (Target 1.B: create sound policy frameworks at the national, regional, and international levels, based on pro-poor and gender-sensitive development strategies) and 10: Reduced Inequalities.

3.3 Insight 5: governance requires systemic change

To harness and embrace the power of migration and migrants for transformations toward sustainability, the systemic barriers that characterize many world cities must be dismantled. While cities are key sites for transformations toward sustainability, and, simultaneously, the main destination of internal and international migration flows, governance approaches remain heavily siloed into disparate and disconnected departments, ministries, and other administrative units. For example, interviews in Belgium, Sweden, the Netherlands, and the United States revealed that there are often more gaps than overlaps between sustainability and migration governance, leading to either inaction, whereby neither party feels that the nexus of migration–sustainability falls within their mandate, or policy incoherence, whereby policy in one domain may hinder, counteract, or undermine policy in another (Zickgraf et al., Reference Zickgraf, Jolivet, Fry, Boyd and Fábos2024). In Bangladesh, the issue of migration is fully absent in the context of urban programs on climate change adaptation in the National Adaptation Plan (GoB 2022b), representing a barrier to fully explore the transformative potential of migration.

To overcome inaction or incoherence that hinders just transitions toward more sustainable societies, it is necessary to overcome persistent mindsets that perceive migration to fall outside the realm of sustainability concerns (Zickgraf et al., Reference Zickgraf, Jolivet, Fry, Boyd and Fábos2024). For example, long-term collaborative initiatives between migrants, policy, and civil society actors working at local, subnational, and national level, within and beyond national borders, have the potential to facilitate innovative thinking and find synergies across horizontal and vertical levels. In Malmö, Sweden, collaborations between mosques and the local government already exist on social issues (Fry & Islar, Reference Fry and Islar2021). Extending collaboration to address sustainability challenges more broadly, and connecting it to higher levels of governance, would enable more innovative thinking (Fry et al., Reference Fry, Boyd, Connaughton, Adger, Gavonel, Zickgraf, Fransen, Jolivet, Fábos and Carr2024). Further, city-to-city dialogues and joint efforts by networks such as the C40 Cities Climate Leadership Group and the Mayors' Migration Council around urban climate migration and displacement have already shown that cross-sectoral collaboration is both possible and beneficial (Zickgraf et al., Reference Zickgraf, Jolivet, Fry, Boyd and Fábos2024).

Further, opening for reflexive conversations and approaches on possibilities to bridge silos can itself be transformative in the sense that it prompts actors involved to find links between migration and aspects of sustainability that they may not previously have considered (Zickgraf et al., Reference Zickgraf, Jolivet, Fry, Boyd and Fábos2024).

3.4 Insight 6: cities cannot do it alone

Transformations inclusive of migration and migrants are unlikely to come about themselves but require purposeful and strategic policy measures across levels of governance. Whilst cities are critical leaders for the migration–sustainability nexus, they cannot do this alone. The agency of cities can be facilitated or constrained by their national and global contexts. In some cases, city budgets and strategies are aligned with the SDGs. The framing of migration within Agenda 2030 as a temporary phenomenon in need of management rather than as an inherent part of sustainable development (Adger et al., Reference Adger, Boyd, Fábos, Fransen, Jolivet, Neville, de Campos and Vijge2019) could misdirect action at the city level, reinforcing assumptions that conflict with broader perspectives of migration and transformation.

Regional and national levels of governance may also constrain city level action on the migration–sustainability nexus. For example, in Bangladesh, Mayor's offices enjoy a limited legal power in many of the areas which are needed to contribute to creating sustainable cities inclusive of migrants. In the Global North, many nation-states are opting for ways to reduce inflows of international migrants, particularly of ‘low-skilled’ workers and asylum seekers who tend to be viewed as a problem in need of control (De Haas et al., Reference De Haas, Czaika, Flahaux, Mahendra, Natter, Vezzoli and Villares-Varela2019). Increased restrictiveness of national-scale migration policies jeopardizes the transformative potential of migration and migrants at the city level. For example, restricted access to state-provided welfare, healthcare, and education and unjust asylum and citizenship policy creates unfavorable conditions for political participation of migrants (Gavonel et al., Reference Gavonel, Adger, Safra de Campos, Boyd, Carr, Fábos, Fransen, Jolivet, Zickgraf, Codjoe, Abu and Siddiqui2021).

Hence, promoting pluralistic sustainability policy and recognizing migrants as actors of sustainability in city destinations is only a partial solution. Vertical coordination, aligning local to global policies, represents critical action points to transformations. Governance should therefore seek to build migration infrastructure, meaning interlinked technologies, institutions, and actors that facilitate mobility, as key enablers to realize the transformative potential of migration for sustainability (Gavonel et al., Reference Gavonel, Adger, Safra de Campos, Boyd, Carr, Fábos, Fransen, Jolivet, Zickgraf, Codjoe, Abu and Siddiqui2021).