Urban agriculture has increasingly gained global recognition as a strategic approach for simultaneously addressing food security and climate change through mitigation and adaptation interventions. However, its potential remains constrained in South Africa, where climate change exacerbates the country’s persistent challenges of food insecurity, poverty, unemployment, inequality, and the triple burden of malnutrition. The study explored the politics of climate change mitigation and adaptation measures for urban agriculture in South Africa. It also identified the fragmentation of related policies and programmes, and the factors that contributed to it. The article examines the nature, causes, and consequences of policy fragmentation by drawing on the available literature. The study systematically reviewed the literature using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 framework. The review used multiple electronic databases, including Scopus, ScienceDirect, and Web of Science, to maximise the retrieval of relevant studies and minimise publication bias. The findings reveal that the separation of climate, agriculture, food security, and urban development governance has resulted in systemic governance failures that hinder policy coherence, resource allocation, and implementation capacity. The study concludes that South Africa will not realise the transformative potential of urban agriculture for climate change mitigation, adaptation, and sustainable food systems unless it shifts from fragmented, sector-specific governance to integrated, coherent, and multi-level policy approaches that recognise the interdependence of climate action, food systems, and urban development. The study contributes to the growing body of knowledge by providing the first comprehensive synthesis of governance fragmentation affecting climate-responsive urban agriculture in South Africa. It also offers evidence-based recommendations for strengthening policy integration, institutional coordination, and adaptive governance.
The transition toward low-carbon transportation has accelerated the adoption of electric mobility in urban transport systems. Unscheduled electric bus services, including charter, tourism, and demand-responsive operations, face operating conditions that differ from fixed-route public transport, particularly variable demand, irregular routes, changing charging opportunities, and coordination across technical, service, cost, and sustainability functions. Existing studies commonly address vehicle technology, charging, scheduling, cost, or environmental performance as separate optimization problems. This study develops and validates the Sustainable Electric Vehicle BUS Model (SEVBUS), an operational measurement architecture designed specifically for unscheduled electric bus services. Its novelty lies in translating fragmented technical and managerial evidence into 48 observable indicators, 19 first-order factors, and a higher-order construct that can be empirically assessed within a single measurement framework. The empirical study was conducted from January to April 2026 in Bangkok, Thailand, involving operators of unscheduled bus services. A sequential instrument-development process comprised structured literature synthesis, indicator screening, item-objective congruence assessment, Delphi validation with 13 experts, and a questionnaire survey of 400 stakeholders. Participants were selected through purposive criterion-based sampling based on their direct knowledge or experience in unscheduled electric bus operations. The study records report an initial pool of 96 candidate indicators, of which 48 were retained. The final sample included 280 drivers, 50 operation control center staff, 50 station or service staff, and 20 operational or fleet managers. Expert agreement was statistically significant (Kendall’s W = 0.438, p < 0.001). Exploratory analysis supported the proposed indicator grouping. The higher-order confirmatory measurement model demonstrated acceptable-to-good fit (CMIN/DF = 1.689, RMSEA = 0.041, and CFI = 0.990). The validated model comprises four dimensions: Electric Bus Capability and Performance (EBCP), Service Scheduling and Utilization Planning (SSUP), Sustainability of Utilization and Operation (SUO), and Operational Cost Efficiency (OCE). Reliability, convergent validity, and discriminant validity met the reported criteria. Correlations among the dimensions ranged from 0.38 to 0.61 (all p < 0.001), indicating statistically significant associations among related but empirically distinguishable operational domains rather than directional or causal effects. The principal contribution of SEVBUS is methodological: it provides a validated multidimensional measurement architecture for examining unscheduled electric bus operations within the studied context of Bangkok, Thailand. Its practical effectiveness as a diagnostic, benchmarking, or decision-support tool remains to be demonstrated through field implementation, independent-sample validation, and objective operational data.
Based on livelihood resilience, social practices, and agency, this paper investigates emergent vulnerabilities within the water, energy, and food (WEF) nexus in Johannesburg’s impoverished settlements. Using a qualitative approach involving observations and interviews, the study examines how low-income households manage nexus risks to meet daily needs. Research was conducted with a purposive sample of 40 respondents from informal dwellings in Alexandra, South Africa. Findings indicate that household vulnerability is primarily linked to food, nutrition, water, and energy insecurity. Consequently, households employ various shifting coping strategies involving formal and informal services to meet daily needs. These WEF trade-offs and practices demonstrate household resilience while highlighting its contingent and unstable nature. The study concludes that Alexandra’s households face significant trade-offs across the WEF nexus, driven primarily by income levels. The findings emphasize the need for cooperative governance and a shift from crisis management to holistic, place-based urban planning. Achieving this requires integrated frameworks where municipalities recognize the heterogeneity of informal settlements and address WEF insecurities as evolving, permanent features of the urban fabric.
Urban morphology in residential complexes can resist heat and generate energy. Across recent studies, key urban morphology indicators consistently linked to passive design that decrease cooling loads in buildings and to active solar strategies that support PV potential. Although post-2020 research links urban morphology to passive and active energy efficiency outcomes, fragmented methods still limit early-stage design guidance. The objective of this scoping review is to synthesize evidence on how urban morphology can manipulate passive design for less heat gain and active solar strategies for generating on-site energy in residential districts tailored to the Middle East and North Africa (MENA) regions. The study followed the PRISMA extension for scoping reviews, implementing eligibility criteria, information sources, database search strategy, selection of sources of evidence, data charting, and synthesis. A total of 33 high-quality studies were identified from major academic databases: Scopus and Web of Science. These studies cover a range of geographical locations, extending from the Middle East and North Africa to parts of South Asia, and tested different urban morphological indicators through parametric design simulations, and field experiments. The synthesis reveals that current research is dominated by passive performance assessment, while only a limited number of studies integrate active solar design. It also highlights a regional gap, as relatively few studies directly address MENA cities despite the region’s severe cooling demand and exceptional solar potential. In response, this study proposes an early-stage conceptual framework that links urban morphology to passive-active energy efficiency outcomes to support concept-phase decisions. The framework also establishes the basis for future machine-learning applications to support generative passive and active energy-efficient urban design in MENA residential contexts.
Personal monitoring of benzene, toluene, ethylbenzene and xylene (BTEX) exposure at municipal solid waste landfills remains scarce in Indonesia, despite its importance for capturing individual exposure variability and improving health risk assessment. This study evaluated inhalation health risks associated with personal BTEX exposure among occupational and residential populations living around an open dumping landfill. Personal air samples were collected from 56 participants, including scavengers, landfill workers, nearby residents and controls group. Personal monitoring was conducted using personal air sampling pumps at 0.045–0.2 L min−1, following NIOSH 1501 Method. BTEX concentrations were analyzed using GC-FID. Benzene was the dominant contributor to non-carcinogenic risk across all exposed groups. Scavengers exhibited the highest non-carcinogenic risk, with a mean Hazard Index (HI) of 3.73 ± 2.36 (p < 0.05). Although the average HI among landfill workers and nearby residents remained below the safety threshold, maximum values reached 3.72 and 1.54, respectively, indicating that some individuals exceeded the acceptable non-carcinogenic risk threshold (HI > 1). Benzene-related carcinogenic risk was also highest among scavengers (4.05 × 10−5 – 1.50 × 10−4). Compared with controls, both non-carcinogenic and carcinogenic risks were 13 times higher among scavengers and four times higher among landfill workers and nearby residents. These findings show open dumping landfills are significant sources of benzene exposure and associated inhalation health risks. They also highlight the urgent need for targeted interventions prioritizing scavengers, strengthened occupational protection and sustainable waste management strategies to reduce health risks among occupational and nearby communities.
IntroductionUrban population shrinkage has become a critical challenge confronting sustainable urban development across China. However, systematic cross-regional and multi-type comparative investigations remain scarce in the existing literature.MethodsTaking the Beijing–Tianjin–Hebei (BTH) region, the Yangtze River Delta (YRD), and the mainland cities of the Guangdong–Hong Kong–Macao Greater Bay Area (GBA) as research objects, this paper investigates the spatiotemporal patterns and driving factors of population shrinkage using panel data from 2010 to 2024. A two-way fixed-effects panel regression model is constructed to examine the impacts of multidimensional factors and their regional heterogeneity.ResultsThe findings reveal pronounced regional heterogeneity. The BTH region presents a shrinkage trajectory spreading from peripheral cities to core metropolitan centers; the YRD experiences extensive mild population shrinkage alongside localized severe contraction; whereas the mainland cities of the GBA maintain steady population growth throughout the study period, with no shrinking cities identified. Two-way fixed-effects models further confirm that natural population growth, economic development, and transportation infrastructure constitute the primary drivers, with their impacts exhibiting significant heterogeneity across the three urban agglomerations.DiscussionIn response to differentiated urban governance needs, this study proposes context-specific smart shrinkage strategies tailored to each urban agglomeration. The findings enrich the empirical literature on urban shrinkage in Chinese megaregions and provide scientific references for sustainable urban management and coordinated regional development policymaking.
Attaining the UN Sustainable Development Goal No. 2, which calls for “zero hunger” by 2030, remains a pipe dream unless challenges imposed on food production systems by climate change are addressed. Climate change poses a huge threat to urban food security in Africa. The objective of this paper is to investigate how climate change is affecting Urban Food Forests, using a case study of an orchard in Harare, by tracking environmental assessment indices between 2013 and 2023. Time series analyses of the Normalized Difference Vegetation Index (NDVI) and Normalized Difference Water Index (NDWI), as well as climate variables, including Standardized Precipitation Evapotranspiration Index (SPEI), Precipitation, Maximum temperature and Minimum temperature, were undertaken in a Google Earth Engine environment. NDVI and NDWI were calculated from Sentinel 2 images, while SPEI data was extracted from the CSIC/SPEI/2_10″ Global SPEI database, and Precipitation, Maximum temperature and Minimum temperature data were derived from Climate Explorer. Data outputs from Google Earth Engine were analyzed further using correlation and multiple regression analyses in an Excel environment. The results indicate that plant health in Urban Food Forests is seriously impacted by the persistence of drought and dry spells arising from climate change. The results also depict shortage of water in the environment, signified by perpetually negative NDWI values, with potential to suppress vegetation health, as indicated by relatively low NDVI values that dominate the time series. These results have potential application for managing Urban Food Forests and transforming the current fragile urban food systems into more robust food systems. The paper concludes that such a transformation would enhance the resilience and adaptive capacity of urban households against climate change. The study recommends the development of mobile based applications that enable urban farmers to monitor NDVI, NDWI and productivity more easily and efficiently.
Urban climate governance sits at the crossroads of democratic legitimacy and decarbonization, with public discourse polarized around inclusion, decision-making, and delivery. Navigating this tension requires more nuanced knowledge about the positions and values activated by climate policies and how political processes engage with diverse positions among civic groups. As such, we develop an analytical framework combining collaborative governance with processual legitimacy to explain when climate action is accepted or contested by diverse citizen groups. The framework is applied to a diverse set of climate protest groups in four Nordic cities—Bergen, Oslo, Gothenburg, and Stockholm—drawing on 95 interviews and policy documents (75 informants across 24 protest groups). We distinguish four different protest logics and link them to input, throughput, and output legitimacy. Throughput legitimacy, defined by day-to-day fairness, accountability, openness, inclusiveness, and responsiveness, emerges as the strongest predictor of contested legitimacy, surpassing policy goals alone. Place-based identities and anti-elite sentiments further modulate perceptions of the legitimacy of climate action when personal burdens and few benefits are observed during implementation. We find that knowledge framing matters, with congruent scientific or local frames fostering constructive dialogue. Input legitimacy, as it unfolds through diverse channels of interaction, also matters: opaque bureaucratic processes erode legitimacy; well-facilitated collaborative arenas build legitimacy; while media campaigns can create conflict and undermine trust and legitimacy. The study argues that contested legitimacy can be addressed by strengthening throughput and trust while maintaining a clear climate direction, advocating a hybrid governance model that pairs rigorous targets with inclusive deliberation, tailored engagement for distinct civic actors, attention to distributive and place-based effects, and robust accountability to reconcile legitimacy, inclusion, and effectiveness in city climate action.
Previous studies show that new drivers’ accident risk drops substantially, e.g. by almost 50% in the first 10 months after getting a driving license. We conduct a systematic literature study to map the mechanisms that explain why the risk of new drivers decreases during the first year and to examine what the research says about which mechanisms are most important to explain this. The results indicate that the risk decreases because of accumulated driving experience, and that the most important mechanism, i.e., the most important things you learn through accumulated driving experience, are improved risk perception and improved distribution of attention. Other mechanisms are improved vehicle handling, improved understanding of your own abilities and limitations, and improved speed control and positioning. We discuss various measures that can provide accumulated driving experience under a safe framework, for example through private practice driving, graded driving licenses and digital tools.
BackgroundActive commuting by walking and cycling offers well-established cardiovascular and metabolic health benefits. However, exposure to ambient air pollutants, including fine particulate matter (PM₂.₅) and nitrogen dioxide (NO₂), during active travel along high-traffic routes may attenuate or offset some of these benefits. Personalised route guidance that minimises pollution exposure while preserving reasonable travel times represents a potentially scalable public health strategy, yet the feasibility and magnitude of achievable exposure reductions remain poorly quantified at the city level.ObjectiveThis proof-of-concept study developed and evaluated a graph-based routing algorithm weighting street-level air pollution concentrations to generate personalised low-pollution routes for pedestrians and cyclists across Leicester, UK, quantifying exposure reductions against conventional shortest-path routing across multiple times of day.MethodsLeicester pedestrian and cycling road networks were retrieved from OpenStreetMap using OSMnx. PM₂.₅ and NO₂ concentration surfaces from the EarthSense MappAir platform were spatially joined to network edges across four diurnal time windows (morning peak, midday, evening peak, off-peak). Twenty representative origin–destination pairs were defined across common residential commuting corridors. Pollution-minimising routes were generated using Dijkstra’s algorithm with min-max normalised, pollutant-weighted edge costs, and compared against shortest-path routes on mean route concentration (MRC, μg m−3), estimated inhaled dose (ID, μg), and route detour.ResultsPollution-minimising routes diverged from shortest-path routes for 129 of 160 combinations (81%). NO₂ MRC reductions were greatest during the evening peak: median 5.9% (IQR: 1.7–23.1%) for walking and 4.4% (IQR: 0.0–27.3%) for cycling, with maximum reductions of 48.5 and 59.9%, respectively. Estimated inhaled NO₂ dose reductions were consistent but modestly smaller (median 3.2% for both modes during the evening peak), reflecting additional travel time on the pollution-minimising route. PM₂.₅ MRC showed negligible changes across all conditions (pooled median 1.0%), reflecting its reduced spatial variability relative to NO₂. Route detours were modest (median 0.94%; IQR: 0.0–4.3%).ConclusionGraph-based pollution-weighted routing achieves meaningful reductions in NO₂ mean route concentration (median 2.89%; max 59.9%) and estimated inhaled dose (median 1.92%) at a median route detour of 0.94%. Equal weighting of PM₂.₅ and NO₂ produced virtually identical NO₂ dose reductions to a NO₂-only formulation (median ID reduction 1.92% vs. 1.91%), confirming that NO₂ is the principal modifiable pollutant through route selection in Leicester. These findings provide a quantitative evidence base for the integration of real-time, personalised NO₂-sensitive navigation into active travel tools.
As U.S. cities expand multimodal transportation networks and pursue Vision Zero goals, crash severity among pedestrians and bicyclists remains a critical public safety challenge. Charlotte, NC, offers a timely case study given its rapid urban growth, rising active transportation demand, and commitment to Vision Zero. This study investigates the human, behavioral, and environmental determinants of pedestrian and bicyclist crash severity in Charlotte, North Carolina, using a five-year crash dataset (2019–2023). Binary logistic regression was applied after evaluating and rejecting ordinal and multinomial approaches due to proportional odds violations and class imbalance. Two models were developed: a primary cause (behavioral) model and an environmental and primary cause model. Crash records were drawn from the Highway Safety Information System (HSIS), supplemented with historical weather data and site inspection to address missing values. The behavioral model found that crashes with no identified contributing circumstance had 2.32 times higher odds of severe injury compared to human-attributed crashes. This association is best interpreted as a crash-documentation artifact, as it attenuates to non-significance once road design and road-user type are controlled. The extended environmental model achieved an AUC of 0.78 (95% CI 0.74–0.82). Daylight reduced severe crash odds by 66%. Divided roads with positive median barriers increased severity risk more than twofold (OR = 2.52). Each additional travel lane raised severity odds by 18%. Urban locations and intersections were also statistically significant predictors, and bicyclists faced substantially lower severity odds than pedestrians (OR = 0.24). Infrastructure design (particularly road division, lane count, and lighting), is a stronger predictor of severe crash outcomes than behavioral fault assignment. Findings support targeted infrastructure interventions in Charlotte’s Vision Zero and active transportation planning efforts.
Urban public spaces play a central role in supporting social interaction, inclusivity, and urban liveability, yet their performance is shaped by cultural, social, and governance contexts. This study examines user experience and perceived inclusivity in urban public spaces through a cross-cultural comparative analysis of three sites: Old Market Square in Nottingham, United Kingdom; Al Balad in Jeddah, Saudi Arabia; and Hazratganj in Lucknow, India. A quantitative research design was adopted using a structured questionnaire with 265 respondents, examining five dimensions of public space experience: accessibility, safety and comfort, inclusivity and equity, perceived publicness, and place meaning and cultural identity. Data were analysed using Exploratory Factor Analysis, Confirmatory Factor Analysis, multi-group measurement invariance testing, ANOVA, post-hoc comparisons, and inter-construct correlation analysis. The findings reveal significant cross-cultural variation in perceived public space experience. Jeddah recorded the highest overall perceived performance, particularly in safety and comfort, inclusivity and equity, and perceived publicness, while Nottingham showed the strongest accessibility scores. Lucknow recorded comparatively lower scores in safety and inclusivity, despite strong place meaning and cultural identity. Correlation analysis showed that accessibility and safety and comfort had the strongest interrelationship, while perceived publicness was closely associated with both accessibility and safety. Place meaning and cultural identity was positively related to all dimensions but showed comparatively weaker associations, suggesting that cultural attachment operates with some independence from functional spatial qualities. The study contributes to urban design research by testing established public space dimensions within a unified cross-cultural framework and by developing the Cross-Cultural Public Space Inclusivity Index as a composite, perception-based analytical tool for comparative assessment. The findings highlight that accessibility alone is insufficient for inclusive public space performance and that culturally responsive planning must integrate safety, social interaction, perceived openness, and place-based identity.
Rainfall increasingly stresses urban road networks, yet how congestion responds across the full range of rainfall intensity, and how that response propagates to rail transit, remains incompletely understood. Drawing on daily data on rainfall, a road Traffic Congestion Index (TCI), and metro ridership in two major cities of the Guangdong-Hong Kong-Macao Greater Bay Area, Guangzhou and Shenzhen, this study fits penalized spline generalized additive models with day-type and seasonal controls, and then employs causal mediation analysis with metro ridership as the key mediating variable to decompose how rainfall’s effect on road congestion propagates to rail transit. Congestion in Guangzhou rises continuously and does not saturate within the observed range (net increment over 20–60 mm of +0.068, 95% Confidence Interval = 0.020–0.115), whereas Shenzhen reaches a bearing ceiling near 40 mm beyond which heavier rainfall has little additional effect (+0.009, 95% Confidence Interval = −0.028–0.046); Guangzhou’s slope is roughly three times that of Shenzhen, and the divergence persists after the 2020 pandemic period is excluded. Although rainfall suppresses metro ridership overall, the metro still absorbs part of the displaced demand, offsetting about 56% of the suppression in Guangzhou and 25% in Shenzhen. The study indicates that traffic resilience depends on the combined influence of multiple factors, and that modal redundancy, improved last-mile metro access, and dynamic, rainfall intensity-based management offer practical means of reducing the vulnerability of urban traffic networks to extreme rainfall events.
The 15-minute city has become a key urban planning concept that encourages the creation of neighborhoods that are accessible to their residents by walking or cycling within 15 min. The concept has been widely discussed in Europe and other developed countries; however, there is not a lot of empirical data available on its implementation in the Gulf cities. The study adopts a convergent mixed-methods research design that combines quantitative survey data with qualitative interviews of stakeholders to explore public perceptions and implementation feasibility of the 15-minute city concept in Dammam, Saudi Arabia. A structured questionnaire was administered to 384 residents of Dammam, and semi-structured interviews were conducted with urban planners, municipal administrators, academics, and real estate professionals. Descriptive statistics, Principal Component Analysis (PCA), and multiple linear regression were used to analyze quantitative data, while thematic analysis was used for the qualitative data. The results show that the public is moderately aware of the 15-minute city concept, while their attitudes are mostly positive about the potential benefits of a 15-minute city in terms of accessibility, environmental sustainability, and quality of life. PCA identified three underlying dimensions of residents' perceptions: accessibility satisfaction, perceived environmental and mobility benefits, and implementation barriers. Multiple linear regression using PCA-derived factor scores showed that accessibility satisfaction and perceived environmental and mobility benefits were significant positive predictors of public support, whereas implementation barriers were negatively associated with support for implementing the 15-minute city concept. The qualitative results showed that urban design that is responsive to climate change, integrated public transport, mixed land use, and coordinated governance are important prerequisites for successful implementation, while climatic conditions, automobile dependence and infrastructure constraints are important challenges. This study provides one of the few empirical mixed-methods assessments of the 15-minute city concept within a Gulf urban context. The findings contribute to the growing literature on proximity-based urban planning and show that the models developed elsewhere should be adapted to the local environmental, spatial, and socio-cultural conditions to be successful in the implementation of proximity-based urban planning in Dammam. The findings offer evidence to support urban planners and policymakers aiming to foster sustainable urban development in the Saudi Vision 2030 agenda.
Sub-Saharan African cities face increasing ecological and sustainability challenges driven by rapid urbanization. Lagos, Nigeria’s commercial hub and one of Africa’s fastest-growing megacities, exemplifies the difficulties of implementing green development principles within complex urban environments. This study examined built environment professionals’ and stakeholders’ perceptions of the implementation of green development principles in Lagos, focusing on environmental management, resource efficiency, sustainable urban design, green transportation, and governance. A quantitative cross-sectional survey was conducted between January and March 2024 using structured questionnaires administered to 384 respondents, including architects, planners, engineers, government officials, academics, and community stakeholders. Data were analysed using descriptive statistics, mean score ranking, and correlation analysis to assess perceived implementation levels, awareness, and barriers to adoption. The findings indicate generally low levels of perceived implementation across all dimensions of green development. Individual implementation indicators recorded mean scores ranging from 1.76 to 3.42 on a five-point scale, while dimension-level means ranged from 2.29 to 2.54. Governance recorded the lowest perceived implementation score (mean = 2.29), with environmental regulation enforcement rated particularly low (mean = 2.12). Respondents demonstrated moderate awareness of green development concepts (mean = 3.28), although awareness of specific local policy frameworks was considerably lower. The results reveal a substantial gap between awareness and practical implementation. The most significant barriers identified were inadequate funding and financial resources (mean severity = 4.32), poor regulatory enforcement (4.21), and limited institutional coordination (4.18). These findings suggest that despite the existence of policy frameworks promoting sustainable urban development, implementation remains constrained by institutional, financial, and governance challenges. The disconnect between policy intentions and on-the-ground realities continues to hinder the realization of green development objectives in Lagos. The study concludes that strengthening policy enforcement, improving inter-agency coordination, expanding stakeholder capacity-building initiatives, and developing context-appropriate financing mechanisms are essential for advancing green development implementation in Lagos and other rapidly urbanizing cities in Sub-Saharan Africa.
Most urban sustainability efforts focus on aspects of climate change and emissions reductions mostly involving technological fixes. These techno-fixes involve massive capital investment and are ‘sold’ to society on the basis of profit-making potential and continuing economic growth, i.e., they designed to extend the unsustainable status quo by alternative means. This orientation is based on a faulty narrative that ignores crucial elements of human evolution, far-from-equilibrium thermodynamics, and ecological limits. While global heating is a potentially horrific problem, it is merely one major co-symptom of the real existential threat, ecological overshoot—urban industrial society is depleting and dissipating the biophysical basis of its own existence. From this perspective, the climate focus is a wasteful distraction. It is not reversing global heating and is actually worsening overshoot and its cause, the excessive scale of urban industrial society. Using natural law and material realities this paper validates the claim that contemporary urbanization is inherently unsustainable. Cities are massive far-from-equilibrium dissipative structures that grow and maintain themselves by extracting energy and material resources from their environments and ‘dissipating’ an equivalent quantity of degraded waste back into those environments. In the process, they necessarily generate exploitive ecological footprints orders of magnitude larger than their built-up or political areas. In short, modern cities flourish at the expense of the entropic disordering of the ecosphere. Corrective change is thwarted by the fact that, for most purposes including provisioning themselves, cities remain dependent on fossil fuels. This creates a genuine predicament: ‘stopping fossil fuels’ would make it impossible to supply and maintain cities, leading to contraction and social disorder, but continuing fossil fuel use (society’s current default position) exposes cities to the dire consequences of possible climate chaos. Urban sustainability requires major reductions of energy/resource consumption and pollution (i.e., ‘environmentally conscious’ low-throughput life-styles) and smaller populations. Earth cannot sustainably support eight let alone an anticipated 10 billion+ people.
Rapid urbanization is placing increasing pressure on cities to deliver affordable, nutritious, and resilient food systems, yet vegetable seedling systems remain a neglected component of urban agriculture. This study assessed urban and peri urban vegetable seedling systems in four rapidly growing cities Addis Ababa (Ethiopia), Nairobi (Kenya), Dhaka (Bangladesh), and Metro Manila (Philippines) to identify key constraints, opportunities, best practices, and policy lessons. Using a comparative multi city case study approach, data were collected from 154 stakeholders, including urban farmers, nursery operators, seedling suppliers, agro input dealers, and government officers, complemented by secondary literature. Across the four cities, urban vegetable production was dominated by small scale, intensive systems cultivating predominantly leafy vegetables, while seedling systems remained underdeveloped, characterized by informal nursery operations, weak quality assurance, open field propagation, limited technical capacity, and fragmented market linkages. These constraints contributed to widespread reliance on direct seeding and low-quality planting material despite strong demand for quality seedlings. Comparative analysis identified opportunities to strengthen commercial and community nursery enterprises through improved propagation technologies, certification systems, digital marketing, commercialization of indigenous vegetable seedlings, and stronger public private partnerships. The study suggests that integrating seedling enterprises into urban food system strategies, supported by improved financing, extension, and quality assurance, could substantially enhance the productivity, resilience, and sustainability of urban vegetable production. As one of the first cross continental assessments of urban vegetable seedling systems in low and middle income countries, the study fills an important evidence gap and positions seedling systems as a critical, yet overlooked, component of resilient and nutrition sensitive urban food systems.
This mini-review presents a case study of an urban photobioreactor Liquid3, which combines microalgae-based air purification with multifunctional urban design to demonstrate the transformative role of bio-inspired techno-environmental innovations. Liquid3 is a public installation designed in accordance with the principles of efficient urban land use, aiming to deliver environmental, social, and economic benefits while addressing key challenges of urban environmental management. Drawing on a transdisciplinary approach, Liquid3 integrates scientific, design, and social perspectives, functioning not only as a technology for CO 2 and particulate matter reduction but also as a driver of societal engagement. The transformative urban design of the Liquid3 photobioreactor fosters environmental awareness, encourages active community engagement, and creates potential for educational applications across diverse cultural contexts. Through social media, Liquid3 may serve as a societal catalyst, reshaping public understanding of ecological processes, the role of technology, and the value of urban greenery, while encouraging civic reflection and new imaginaries for sustainable cities. In terms of its educational potential, Liquid3 may function both as a model of economically viable environmental innovation and as a pedagogical tool. Ultimately, this case study underscores the critical role of transformative urban design as a framework for discussing and reimagining sustainable urban futures.
