# Citizen Science initiatives in climate-vulnerable neighbourhoods: a new transdisciplinary approach to tackle sustainability challenges?

Isabelle Bonhoure, Josep Perelló

► To cite this version:

Isabelle Bonhoure, Josep Perelló. Citizen Science initiatives in climate-vulnerable neighbourhoods: a new transdisciplinary approach to tackle sustainability challenges?. Les Cahiers Espace, Environnement, Risques et Résilience, 2025. hal-05354419

HAL Id: hal-05354419

https://hal.science/hal-05354419v1

Submitted on 7 Nov 2025

HAL is a multi-disciplinary open access
archive for the deposit and dissemination of sci-
entific research documents, whether they are pub-
lished or not. The documents may come from
teaching and research institutions in France or
abroad, or from public or private research centers.

L'archive ouverte pluridisciplinaire HAL, est
destinée au dépôt et à la diffusion de documents
scientifiques de niveau recherche, publiés ou non,
émanant des établissements d'enseignement et de
recherche français ou étrangers, des laboratoires
publics ou privés.

<figure><img src="image_1.png" /></figure>

Distributed under a Creative Commons Attribution 4.0 International License
<figure><img src="image_2.png" /></figure>

# Citizen Science initiatives in climate-vulnerable neighbourhoods: a new transdisciplinary approach to tackle sustainability challenges?

Isabelle Bonhoure<fnref n="1" />,<fnref n="2" />, Josep Perelló<fnref n="1" />,<fnref n="2" />

Reçu le 16 octobre 2025, publié le 7 novembre 2025

According to the Spanish State Meteorological Agency (AEMET), the summer of 2025 (June 1–August 31) was exceptionally warm across Spain, with an average temperature of 24.2°C on the mainland. This value is 2.1°C above the seasonal average for the reference period 1991–2020. It was the warmest summer since records began in 1961, surpassing the previous record set in 2022 by 0.1°C.

Barcelona and its metropolitan area, located along the Catalan coast, have been particularly affected by rising summer temperatures, a situation exacerbated by the urban heat island effect (Ward et al., 2016; Zhao et al., 2018). On 16 August 2025, a temperature of 38.9°C was recorded at the Fabra Observatory, one of the city's four official meteorological stations. This value exceeded the previous August record of 38.8°C, registered in 2023. Furthermore, according to an international study (Barnes et al., 2025), Barcelona reported the third-highest number of heat-related deaths among European cities during the summer of 2025, surpassed only by Milan and Rome.

While extreme heat has become an increasing concern in Barcelona and its metropolitan area, its impacts on well-being are unevenly distributed, disproportionately affecting specific, more climate-vulnerable social groups and neighborhoods (Mashhoodi, 2021). These disparities link thermal inequity to broader issues of climate (in)justice (Kotsila et al., 2025). However, how residents experience heat at the micro-local scale remains largely understudied across the Barcelona metropolitan region, which encompasses neighborhoods with markedly diverse socioeconomic characteristics.

It is clear that a new transdisciplinary and participative approach is needed to address this complex real-world urban sustainability challenge. As articulated in the foundational paper by Lang et al. (2012) on transdisciplinary research in sustainability science, such challenges require new knowledge production and decision-making methods and the involvement of actors from outside academia in the research process. Lang et al. (2012) define transdisciplinarity as “a reflexive, integrative, method-driven scientific principle aiming at the solution or transition of societal problems and concurrently of related scientific problems by differentiating and integrating knowledge from various scientific and societal bodies of knowledge.”

Lang et al. (2012) propose a model that conceptualizes transdisciplinary research in sustainability science as an “interface practice that originates from societally relevant problems that imply and trigger scientific research questions,” and that “relies on mutual and joint learning processes between science and society embedded in societal and scientific discourse.” The authors also outline twelve design principles for transdisciplinary research that include building a collaborative research team, developing a shared understanding of the problem, and devising a methodological framework.

This participatory and reflexive orientation of transdisciplinarity closely aligns with Citizen Science (CS) practices. CS can be broadly understood as the active engagement of the general public in scientific

<footnote n="1">¹ OpenSystems Research Group, Departament de Física de la Matèria Condensada, Universitat de Barcelona, Martí i Franquès, 1, 08028 Barcelona, Spain</footnote>

<footnote n="2">² Universitat de Barcelona Institute of Complex Systems UBICS, Martí i Franquès, 1, 08028 Barcelona, Spain</footnote>
research tasks (Vohland et al., 2021). It can contribute to sustainability transformations by shaping research agendas, mobilizing resources, and fostering socio-technical co-evolution, while simultaneously generating new forms of interdisciplinary scientific knowledge (Sauermann et al., 2020). A recent systematic literature review (Bonhoure et al., 2025) further highlights the contribution of CS to sustainable urban transformation, bringing new research methodologies and scientific results to research topics such as air pollution (Lu et al., 2022; Mahajan et al., 2024; Perelló et al., 2021), participatory urban planning (Fermeglia and Pedrosa, 2022; Franco and Cappa, 2021; Pitidis et al., 2024) and One Health (Bhandari, 2024; Ellwanger et al., 2022; Manikam et al., 2020).

Refocusing on the issue of urban extreme heat, an increasing number of studies have employed citizen science methodologies to investigate this phenomenon (Calhoun et al., 2024; Kim et al., 2024; Kousis et al., 2021; Lehnert et al., 2021; Leichtle et al., 2023; Rosso et al., 2022). CS is a powerful way to place urban citizen views, perceptions and lived experiences at the center of the research. Another recent review (Freschi et al., 2024) highlights the growing potential of Citizen Science (CS) to inform climate governance and action and confirms its capacity to contribute to climate change research in urban contexts from multiple perspectives and thematic angles. This is particularly evident in the framework of citizen social science, in which participatory research is co-designed and directly driven by citizen groups united by shared social concerns (Albert et al., 2021; Bonhoure et al., 2023). When targeting urban issues such as heat, this framework highlights the active role of co-researchers—residents who possess local, experiential knowledge of their neighborhoods and who share a collective concern about urban heat—in shaping both the research questions and outcomes.

In this context, the Heat Chronicles CS project (Cròniques de la Calor in Catalan) was implemented in 2023 and 2024 across five neighborhoods in the Barcelona metropolitan area. The project forms part of the Universitat de Barcelona Hub for Global Sustainability, a transversal research alliance that brings together academic and technical staff from various research groups across 15 different faculties. The Hub strives to intensify efforts to overcome current crises by strengthening interdisciplinary collaboration within the university community.

In Heat Chronicles, neighborhoods were selected based on their residents' heightened vulnerability to extreme heat, primarily associated with socioeconomic and urban-structural factors (Garcia-Sierra et al., 2022). In each neighborhood, a collaborative research team was established, bringing together 14 partner organizations, including educational institutions (kindergartens, primary and secondary schools, as well as specialized education centers), civil society organizations (e.g., NGOs working with children and young people in situations of social vulnerability), and community facilities (such as public libraries, community centers, and neighborhood assemblies). Collaboration with these local institutions facilitated a deeper understanding of the specific challenges associated with extreme heat, further enriched through a series of walking explorations conducted by the research team across the participating areas.

In total, nearly 500 residents participated, sharing their experiences as primary and secondary school students, families with toddlers, young users of civil society organizations, public library users or self-organized groups of elderly people.

The citizens' groups first identified and characterized the most relevant public spaces in their neighborhoods and then took part in collective “thermal walks.” During these walks, continuous geolocated temperature data were collected using customized low-cost sensors (see Figures 1a and 1b). At each of the previously identified public spaces, participants paused to individually and anonymously report their perceptions of thermal comfort and sensation (see Figures 1c and 1d).

The results were collectively interpreted within each neighborhood, while the overall dataset was analyzed at a metropolitan scale. In total, 52 thermal walks were conducted, covering 211 public spaces and yielding approximately 3,000 thermal comfort votes and 2,000 thermal sensation responses.
<figure><img src="image_3.png" /><figcaption>**Figure 1.** Heat Chronicles' collective thermal walks:</figcaption></figure>

(1) Collection of a continuous geolocated set of temperatures (a and b), and (2) individual anonymous thermal votes on thermal comfort and sensation (c and d).

At the local scale, the findings revealed that accessing basic facilities—such as health centers (Figure 1d) or metro stations—often requires walking routes that are fully exposed to extreme heat. Similarly, leisure facilities such as football pitches were frequently found to be unusable under current climatic conditions, while access to cooler areas like urban forests proved challenging. The project also highlighted residents' strong willingness to engage in the research process and to be recognized as knowledgeable members of their communities. Older adults valued the opportunity to share their lived experiences during heat waves and, despite mobility limitations, expressed a desire to participate in the collective thermal walks. Children and teenagers likewise emphasized their sense of belonging to the community and sought to challenge adult-centered urban design paradigms.

At a broader level, the data generated by Heat Chronicles provided a unique opportunity to examine how heat perception is influenced by factors such as gender, age, and residents' personal relationships with their neighborhoods. The physical characteristics of the urban spaces visited—including use, Sky View Factor, Normalized Difference Vegetation Index (NDVI), shade, and wind conditions—also played a decisive role in shaping both thermal sensation and comfort. The nuances and complexities of this multidimensional issue call for sophisticated data science techniques and challenge the limitations of disciplinary research approaches. The crowd-sourced data collected are motivated by residents' concerns and might not meet the expectations of professional scientists, and vice versa. There is also the need to find new ways of bringing together complementary discourses to make the voice of groups of residents stronger and to deliver scientific outcomes which lead to effective sustainability transformations.

Returning to the concept of transdisciplinarity, Heat Chronicles embodies many of the principles outlined by Lang et al. (2012) for conducting transdisciplinary sustainability research. Addressing a real-world problem and generating socially robust knowledge, the project is transdisciplinary by design, organically integrating disciplines such as meteorology, urban planning, Geographic Information Systems and data science, and ethnography. It employs diverse methodologies—including community and participatory mapping, co-creation processes, and exploratory walks—that foster collaboration between scientific and societal actors. Heat Chronicles has also fostered a shared understanding and
collective definition of the problem to be addressed, through collaboration with diverse institutions and citizens' groups, in the spirit of mutual learning. The project also developed a new methodological framework, informed by experience from previous CS projects (Perelló et al., 2021), in which citizens determined the locations of measurements based on their expert knowledge as users of public spaces.
To conclude, CS initiatives implemented in climate-vulnerable neighborhoods offer a valuable opportunity to fully embrace a transdisciplinary perspective, transforming conventional scientific methods and protocols while simultaneously enhancing the societal relevance and impact of research.

References:

Albert, A., Balázs, B., Butkevičienė, E., Mayer, K., Perelló, J., 2021. Citizen Social Science: New and Established Approaches to Participation in Social Research, in: Vohland, K., Land-Zandstra, A., Ceccaroni, L., Lemmens, R., Perelló, J., Ponti, M., Samson, R., Wagenknecht, K. (Eds.), The Science of Citizen Science. Springer International Publishing, Cham, pp. 119–138. https://doi.org/10.1007/978-3-030-58278-4_7

Barnes, C., Konstantinoudis, G., Masselot, P., Mistry, M., Gasparrini, A., Vicedo-Cabrera, A.M., Theokritoff, E., Clarke, B., Otto, F., 2025. Summer heat deaths in 854 European cities more than tripled due to climate change. https://doi.org/10.25560/123873

Bhandari, M.P., 2024. Citizen Science and its Applicability for Sustainability and a Healthy Planet. Acad. Environ. Sci. Sustain. 1. https://doi.org/10.20935/AcadEnvSci7270

Bonhoure, I., Cigarini, A., Vicens, J., Mitats, B., Perelló, J., 2023. Reformulating computational social science with citizen social science: the case of a community-based mental health care research. Humanit. Soc. Sci. Commun. 10, 81. https://doi.org/10.1057/s41599-023-01577-2

Bonhoure, I., Guba, B., Peer, C., Labastida, I., Perelló, J., 2025. Citizen science contributions to sustainable urban transformation and urban sustainability: a systematic literature review. https://doi.org/10.31235/osf.io/zc7w4_v1

Calhoun, Z.D., Black, M.S., Bergin, M., Carlson, D., 2024. Refining Citizen Climate Science: Addressing Preferential Sampling for Improved Estimates of Urban Heat. Environ. Sci. Technol. Lett. 11, 845–850. https://doi.org/10.1021/acs.estlett.4c00296

Ellwanger, J.H., Byrne, L.B., Bogo Chies, J.A., 2022. Examining the paradox of urban disease ecology by linking the perspectives of Urban One Health and Ecology with Cities. URBAN Ecosyst. https://doi.org/10.1007/s11252-022-01260-5

Fermeglia, M., Pedrosa, K., 2022. Planning for Citizens’ Health: Towards an Integrated Approach to Air and Noise Pollution in the EU. J. Eur. Environ. Plan. LAW 19, 9–30. https://doi.org/10.1163/18760104-19010003

Franco, S., Cappa, F., 2021. Citizen science: involving citizens in research projects and urban planning. TEMA-J. LAND USE Mobil. Environ. 14, 114–118. https://doi.org/10.6092/1970-9870/7892

Freschi, G., Menegatto, M., Zamperini, A., 2024. Conceptualising the Link between Citizen Science and Climate Governance: A Systematic Review. Climate 12, 60. https://doi.org/10.3390/cli12050060

Garcia-Sierra, M., Domene, E. & Andreu, M. Heat in a future: Index of vulnerability to climate change (IVAC) (2022). https://www.institutmetropoli.cat/en/estudi/heat-in-a-future-index-of-vulnerability-to-climate-change-ivac

Kim, E.S., Bae, C., Ko, S.Y., Won, J.E., Lee, J.H., Paio, Y., Lee, D.K., 2024. Enhancing the effectiveness of heat adaptation strategies through citizen science-based outdoor thermal comfort. Heliyon 10, e39413. https://doi.org/10.1016/j.heliyon.2024.e39413

Kotsila, P., Cuenca, V., Franco, M., Melo, L., Pickard, S., 2025. EMBODYING AND RESISTING URBAN HEAT INJUSTICE: Migrant Vulnerabilities and Radical Adaptations in El Raval, Barcelona. Int. J. Urban Reg. Res. 1468-2427.13359. https://doi.org/10.1111/1468-2427.13359

Kousis, I., Pigliautile, I., Pisello, A.L., 2021. Intra-urban microclimate investigation in urban heat island through a novel mobile monitoring system. Sci. Rep. 11. https://doi.org/10.1038/s41598-021-88344-y
Lang, D.J., Wiek, A., Bergmann, M., Stauffacher, M., Martens, P., Moll, P., Swilling, M., Thomas, C.J., 2012. Transdisciplinary research in sustainability science: practice, principles, and challenges. Sustain. Sci. 7, 25–43.
https://doi.org/10.1007/s11625-011-0149-x

Lehnert, M., Geletič, J., Kopp, J., Brabec, M., Jurek, M., Pánek, J., 2021. Comparison between mental mapping and land surface temperature in two Czech cities: A new perspective on indication of locations prone to heat stress. Build. Environ. 203. https://doi.org/10.1016/j.buildenv.2021.108090

Leichtle, T., Kühnl, M., Droin, A., Beck, C., Hiete, M., Taubenböck, H., 2023. Quantifying urban heat exposure at fine scale - modeling outdoor and indoor temperatures using citizen science and VHR remote sensing. Urban Clim. 49, 101522. https://doi.org/10.1016/j.uclim.2023.101522

Lu, T., Liu, Y., Garcia, A., Wang, M., Li, Y., Bravo-villasenor, G., Campos, K., Xu, J., Han, B., 2022. Leveraging Citizen Science and Low-Cost Sensors to Characterize Air Pollution Exposure of Disadvantaged Communities in Southern California. Int. J. Environ. Res. Public. Health 19. https://doi.org/10.3390/ijerph19148777

Mahajan, S., Mondardini, R., Helbing, D., 2024. Democratizing air: A co-created citizen science approach to indoor air quality monitoring. Sustain. Cities Soc. 116, 105890. https://doi.org/10.1016/j.scs.2024.105890

Manikam, L., Bou Karim, Y., Boo, Y.Y., Allaham, S., Marwaha, R., Parikh, P., Lakhanpaul, M., On behalf of the Childhood Infections and Pollution Consortium, 2020. Operationalising a One Health approach to reduce the infection and antimicrobial resistance (AMR) burden in under-5 year old urban slum dwellers: The Childhood Infections and Pollution (CHIP) Consortium. One Health 10. https://doi.org/10.1016/j.onehlt.2020.100144

Mashhoodi, B., 2021. Environmental justice and surface temperature: Income, ethnic, gender, and age inequalities. Sustain. Cities Soc. 68, 102810. https://doi.org/10.1016/j.scs.2021.102810

Perelló, J., Cigarini, A., Vicens, J., Bonhoure, I., Rojas-Rueda, D., Nieuwenhuijsen, M.J., Cirach, M., Daher, C., Targa, J., Ripoll, A., 2021. Large-scale citizen science provides high-resolution nitrogen dioxide values and health impact while enhancing community knowledge and collective action. Sci. Total Environ. 789, 147750.
https://doi.org/10.1016/j.scitotenv.2021.147750

Pitidis, V., Coaffee, J., Lima-Silva, F., 2024. Advancing equitable “resilience imaginaries” in the Global South through dialogical participatory mapping: Experiences from informal communities in Brazil. CITIES 150. https://doi.org/10.1016/j.cities.2024.105015

Rosso, F., Pioppi, B., Pisello, A.L., 2022. Pocket parks for human-centered urban climate change resilience: Microclimate field tests and multi-domain comfort analysis through portable sensing techniques and citizens’ science. Energy Build. 260, 111918. https://doi.org/10.1016/j.enbuild.2022.111918

Sauermann, H., Vohland, K., Antoniou, V., Balázs, B., Göbel, C., Karatzas, K., Mooney, P., Perelló, J., Ponti, M., Samson, R., Winter, S., 2020. Citizen science and sustainability transitions. Res. Policy 49, 103978.
https://doi.org/10.1016/j.respol.2020.103978

UN-Habitat, 2024. World Cities Report 2024 Cities and Climate Action.

Vohland, K., Land-Zandstra, A., Ceccaroni, L., Lemmens, R., Perelló, J., Ponti, M., Samson, R., Wagenknecht, K., 2021. Editorial: The Science of Citizen Science Evolves, in: Vohland, K., Land-Zandstra, A., Ceccaroni, L., Lemmens, R., Perelló, J., Ponti, M., Samson, R., Wagenknecht, K. (Eds.), The Science of Citizen Science. Springer International Publishing, Cham, pp. 1–12. https://doi.org/10.1007/978-3-030-58278-4_1

Ward, K., Lauf, S., Kleinschmit, B., Endlicher, W., 2016. Heat waves and urban heat islands in Europe: A review of relevant drivers. Sci. Total Environ. 569–570, 527–539. https://doi.org/10.1016/j.scitotenv.2016.06.119

Zhao, L., Oppenheimer, M., Zhu, Q., Baldwin, J.W., Ebi, K.L., Bou-Zeid, E., Guan, K., Liu, X., 2018. Interactions between urban heat islands and heat waves. Environ. Res. Lett. 13, 034003. https://doi.org/10.1088/1748-9326/aa9f73