Achieving Carbon Mitigation with Economic Benefits through High-Resolution Analysis of Renewable Resource Integration in Global Coastal Cities

Coastal regions, home to more than half of the global population and contributing over 50% to the global economy, possess vast renewable resources, such as seawater and solar energy. The effective utilization of these resources, through the seawater-cooled district cooling system (SWDCS), seawater toilet flushing (SWTF), and rooftop solar photovoltaic system (RTPV), has the potential to significantly reduce carbon emissions. However, implementing these technologies in different geographic contexts to achieve the desired carbon and economic outcomes at the city level lacks a clear roadmap. To address this challenge, we comprehensively analyzed 12 coastal megacities worldwide by integrating geospatial building data. Our study evaluated the potential energy savings, carbon mitigation, and levelized carbon abatement costs (LCACs) from a life cycle perspective. The results revealed that using seawater and solar energy within urban boundaries can reduce electricity consumption from 1 to 24% across these cities. The spatial distribution of the LCAC for seawater-based systems exhibited more variation compared to the RTPV. By applying specific LCAC thresholds ranging from 0 to 225 USD/tCO2e, all cities could achieve both carbon reductions and economic benefits. These thresholds resulted in up to 80 million tonnes of carbon emission reductions and 5 billion USD of economic benefits, respectively. Our study provides valuable insights into integrating renewable resource systems, enabling coastal cities to achieve carbon and economic advantages at the city scale simultaneously.

Data Insights for Sustainable Cities: Associations between Google Street View-Derived Urban Greenspace and Google Air View-Derived Pollution Levels

Unprecedented levels of urbanization have escalated urban environmental health issues, including increased air pollution in cities globally. Strategies for mitigating air pollution, including green urban planning, are essential for sustainable and healthy cities. State-of-the-art research investigating urban greenspace and pollution metrics has accelerated through the use of vast digital data sets and new analytical tools. In this study, we examined associations between Google Street View-derived urban greenspace levels and Google Air View-derived air quality, where both have been resolved in extremely high resolution, accuracy, and scale along the entire road network of Dublin City. Particulate matter of size fraction less than 2.5 μm (PM2.5), nitrogen dioxide, nitric oxide, carbon monoxide, and carbon dioxide were quantified using 5,030,143 Google Air View measurements, and greenspace was quantified using 403,409 Google Street View images. Significant (p < 0.001) negative associations between urban greenspace and pollution were observed. For example, an interquartile range increase in the Green View Index was associated with a 7.4% [95% confidence interval: -13.1%, -1.3%] decrease in NO2 at the point location spatial resolution. We provide insights into how large-scale digital data can be harnessed to elucidate urban environmental interactions that will have important planning and policy implications for sustainable future cities.

Trees, Climate Change, and Health: An Urban Planning, Greening and Implementation Perspective

The In Conversation: Boundary, Spanners, Thinkers and Policy Actors Round Table Series provides a platform for researchers, policy actors, and implementation experts to elevate discussion on emerging issues, present new and upcoming research, and facilitate conversations around impacts and possible solutions. This brief report, on trees, climate change, and health, reflects a conversation between the authors of this paper, along with supporting literature. It explores the potential of green spaces and trees as a viable strategy to address climate change challenges and simultaneously improve population health, well-being, and health equity. In particular, it highlights the public health benefits of trees and green space, the challenges faced in urban areas, and opportunities for the protection, maintenance and regeneration of urban green space.

Current Practices and Opportunities for More Sustainable Public Food Procurement: A Qualitative Study among Danish Municipalities and Regions

Public food procurement has been emphasized as a powerful tool to promote a healthier and more sustainable food system, but there is still a long way to go to reach full potential. This study aimed to investigate practices and opportunities for sustainable and healthy public food procurement. A qualitative cross-sectional study was performed among Danish municipalities and regions stratified and randomly selected to cover standard practice (n = 17). In addition, interviews were performed among selected best-practice municipalities (n = 5) providing examples of ambitious goals and well-defined processes for obtaining sustainable food procurement. Large differences were observed in the cross-sectional analysis in relation to policy support and goals for sustainable food procurement, including organic purchase. Generally, there was a great attentiveness to reduce food waste and many valued the use of local food, especially among rural municipalities, whereas experience with climate impact reduction and shifts towards more plant-based menus was still in an early implementation stage. Results suggest a possible synergy effect between the use of organic food and efforts to reduce food waste and climate impact and emphasize the importance of local government policies to promote healthy and sustainable food procurement. Enabling factors to move sustainable food procurement forward are discussed.

Entropy and Cities: A Bibliographic Analysis towards More Circular and Sustainable Urban Environments

Cities are critical to a sustainable future for our planet; still, the construction and operation of cities rely on intensive resource and energy use and transformation, leading to the generation of waste, effluents, and pollution, representing negative externalities outside and inside the city. Within every process, transformation implies the use of energy and the increase of entropy. In an urban system, the transformation of energy and materials will trigger the creation of entropic landscapes, mainly in the informal city and in unguarded natural landscapes, even hundreds of kilometers away, which generates substantial economic, social, and environmental impacts. In this sense, cities are significant contributors to the environmental crisis. Upstream, degradation of landscapes and ecosystems is frequent. Cities' externalities and exogenous consumptions are directly linked with entropy and entropic landscapes, which are recognized as pollution (in the air, water, and land) or waste and in the degradation of natural ecosystems and communities. Through a systematic review of existing literature, this paper first outlines briefly how entropy has been applied in different disciplines and then focuses on presenting recent developments of how entropy has been defined, used, and characterized in urban studies concerning sustainability in cities and architecture, and presents a definition of the concept in relation to urban systems and key aspects to consider.

How Can Resource-Exhausted Cities Get Out of "The Valley of Death"? An Evaluation Index System and Obstacle Degree Analysis of Green Sustainable Development

Resource-based cities are suffering from resource scarcity and environmental deterioration. Spirit, vitality and prosperity are disappearing and cities have moved towards "the valley of death" in terms of urban development. This typically appears in environments where it is difficult to maintain sustainable development. Based on empirical analysis, a qualitative analysis method for the selection of evaluation indicators, as well as a quantitative analysis method for index weighting and principal component extraction for constructing a three-level evaluation index system of green development for coal-resource-exhausted cities, was adopted. This study also discussed the life cycle at different development stages of resource-based cities, including mature resource-based and growing resource-based cities. We further argued that the obstacle degree can act as an evaluation basis and make recommendations accordingly to improve the green development of cities. Through star-standard divisions and statistical analysis, it can be explicated that the increase in green development in the first stage is greater than that in the later stage, which is more obvious in cities with lower stars. The results also show the evolution trend and stability coefficient. There is no end in sight for urban green development, and this study can provide a new perspective to relieve the declining trend and promote green sustainable development.

SDG-11 and smart cities: Contradictions and overlaps between social and environmental justice research agendas

There is an increased role Information and Communications Technology (ICT) plays in the achievement of Sustainable Development Goals (SDGs). This paper focuses specifically on SDG-11 "Make cities and human settlements inclusive, safe, resilient and sustainable" and how cities are increasingly incorporating ICT toward this goal. The public discourse on Smart Cities suggests economic, social and environmental benefits are possible through the use of Information and Communication Technology (ICT). However, the increased deployment and use of digital infrastructure and processes in the name of sustainability and optimization itself is the focus of a growing body of critical literature on Smart Cities. This mini-review collates critical literature on digital infrastructures and processes related to SDG-11 and Smart Cities to identify areas of significance for further research. Although many Smart City projects discuss sustainability benefits, the distribution of benefits and risks across different communities is rarely examined. An increased use of ICT in Smart City projects can provide environmental benefits to some communities, while shifting the burden of risks to other communities. An increased use of ICT has its own energy and resource impacts that has implications for sustainability beyond the geography of individual cities to global impacts. The lifecycle and supply chain impacts of advanced ICT projects are being identified and documented. The end user of the Smart City projects may benefit significantly from the increased use of ICTs, while the environmental costs are often borne by disparate communities. In some cases, within the same city where a Smart City project is deployed, the inequities in distribution of environmental resources and services are exacerbated by layering new ICT implementations on top of existing socio-economic inequities. Therefore, this paper combines a broad view of Smart City environmental impacts, as well as a deep examination of the intersection of social justice and environmental justice issues to create more wholistic approaches for analysis of governance of Smart City projects. A more wholistic approach for governance of Smart City projects is required that includes combined social justice and environmental justice frameworks, toward achievement of SDG-11 goals.

Climate Change Prevention through Community Actions and Empowerment: A Scoping Review

As society tries to tackle climate change around the globe, communities need to reduce its impact on human health. The purpose of this review is to identify key stakeholders involved in mitigating and adapting to climate change, as well as the type and characteristics of community empowerment actions implemented so far to address the problem. Published and unpublished studies from January 2005 to March 2022 in English and Portuguese were included in this review. The search, conducted on PubMed, CINAHL, Scopus, MEDLINE, Scopus, Web of Science, SciELO, and RCAAP (Repositório Científico de Acesso Aberto de Portugal), followed a three-step search strategy. Data extraction was performed by two independent reviewers, using an extraction tool specifically designed for the review questions. Twenty-seven studies were eligible for inclusion: six used interviews as a qualitative method, three were systematic reviews, three were case study analyses, three used surveys and questionnaires as quantitative methods, two used integrative baseline reviews, and three utilized a process model design. Six studies targeted local, public and private stakeholders. Community settings were the context target of fifteen studies, whereas twelve specifically referred to urban settings. Seven types of community actions were acknowledged across the globe, characterised as hybrid interventions and referring to the leading stakeholders: local governments, non-governmental organizations, civil society, universities, public health, and private sectors.

Smarter and Greener Cities After COVID-19: An Integrated Decision-Making Framework to Prioritize Investment Alternatives

Locking down cities to curb the transmission of coronavirus brought the global economy to a grinding halt. Cities are like engines of growth; when they stop, so does the growth. Therefore, it becomes paramount to build cities that continue to function and do not collapse amidst any crisis. Since economic recovery is underway, this paper examines priority areas for investment to expedite recovery and build back stronger cities. These areas are evaluated based on their contribution to revitalizing public health, economic, social, energy, and environmental sectors. For the analysis, analytical network process (ANP) and fuzzy-VIKOR are applied. ANP obtains the relative importance of sectors and their respective critical factors after solving a complex relationship among them. The economic sector has the highest weight of 25.8% among the five sectors, while job creation has the highest weight of 10.3% among the fifteen factors. Fuzzy-VIKOR is used to evaluate different areas and it is found that renewable energy has a greater contribution to the sustainable recovery of major sectors and the long-term aim of building inclusive green and resilient cities. These insights shall contribute to the conversations already ongoing among city governments, urban planners, civil society organizations, and city dwellers seeking practical solutions to unprecedented challenges posed by the pandemic.

Programming Nature as Infrastructure in the Smart Forest City

Smart cities typically involve the digitalization of transport and buildings, energy and communications. Yet urban natures are also becoming increasingly digitalized, whether through processes of monitoring, automation, mitigation, or augmentation. This text considers what "splintering urbanisms" materialize through programming nature as infrastructure. By focusing specifically on smart urban forests, I suggest that the management logics of smart infrastructures attempt to program and transform vegetation and its ecologies into uniquely efficient and responsive urban organisms. In the process, these programs of efficiency have the potential to exacerbate extractive economies and social inequalities that amplify and materialize through the "Internet of nature."

Comparison of organic substrates in urban rooftop agriculture, towards improving crop production resilience to temporary drought in Mediterranean cities

BACKGROUND

Urban agriculture contributes to meeting the growing food production demand in cities. In the context of low water availability, it is important to consider alternatives that are able to maintain production. Through a circular economy vision, this study aimed to assess the use of substrates made from local materials as an alternative for urban agriculture in periods of low water availability, due to water supply cuts. The substrates used were coir commercial organic substrate, vegetable compost from urban organic waste and perlite commercial standard substrate; a mixture of the urban compost and perlite (1:1) was used for three consecutive crop cycles of lettuce (Lactuca sativa L. var. crispa). The crop cycles were performed in the spring and summer periods of 2018 to observe the performance during warmer periods of the year in an integrated rooftop greenhouse near Barcelona. Each substrate was assessed under conventional irrigation (0-5 kPa) and temporary water restricted conditions (irrigation stopped until the water tension reached -20 kPa perlite).

RESULTS

In terms of yield, our results show that the compost and mixture were similar to those obtained from perlite (11.5% and 3.7% more production under restricted water conditions). Organic substrates increased the crop's resilience to water restriction, in contrast to the perlite. In particular, water loss took longer in coir (one- and two-crop cycle); however, when dryness began, it occurred quickly.

CONCLUSION

The vegetable compost and the substrate mixture presented tolerance to temporary water restriction when water restriction reached -20 kPa. © 2021 Society of Chemical Industry.

Partnerships for sustainable cities as options for improving solid waste management in Nairobi city

Partnerships as enshrined in policies are vital for achieving sustainable cities under the Sustainable Development Goals (SDGs). Indeed the SDGs recognize the importance of partnerships in solid waste management (SWM) as a way of developing workable and reliable waste management systems. SWM in Nairobi city continues to be a great challenge, and poor practices threaten environmental and public health. Ineffective waste management in Nairobi city has been linked to inefficient policy implementation and enforcement by different stakeholders. To effectively address the challenge of sustainable waste management in Nairobi city, amalgamation of strategies amongst several segments, including stakeholders, private and public sectors (formal and informal), non-governmental organizations and communities, is important, through partnerships to implement improved policies, in terms of capacity, financial prudence, and technical and institutional factors. The paper seeks to analyse existing policy framework on SWM and its effectiveness in addressing SWM in Nairobi city. The study is based on a descriptive research design which involved interrogating the stakeholders included in the implementation of the policy frameworks in place. Data were acquired through semi-structured questionnaires administered to 385 respondents and interviews with 10 key informants. The theoretical framework is based on institutional theory and capacity building theories that expound the gaps in policy implementation and the role of partnerships. Policies in SWM should be interlinked for sustainable cities.

Informal Work and Sustainable Cities: From Formalization to Reparation

Informal workers produce economic, social, and environmental value for cities. Too often, policy elites, including those promoting sustainable cities, overlook this value, proposing formalization and relying on deficit-based framings of informal work. In this perspective piece, we bring critical research and community-produced knowledge about informal work to sustainability scholarship. We challenge the dominant, deficit-based frame of informal work, which can dispossess workers, reduce their collective power, and undercut the social and environmental value their work generates. Instead, thinking historically, relationally, and spatially clarifies the essential role of informal work for urban economies and highlights their potential for promoting sustainable cities. It also reveals how growth-oriented economies reproduce environmental destruction, income inequality, and poverty, the very conditions impelling many to informal work. Rather than formalization, we propose reparation, an ethic and practice promoting ecological regeneration, while redressing historic wrongs and redistributing resources and social power to workers and grassroots social movements.

Electric Vehicle Charging Station Location towards Sustainable Cities

Electric vehicles, a significant part of sustainable transport, are attracting increasing attention with the development of sustainable cities. However, as supporting facilities of electric vehicles, public charging stations are of great significance to the promotion of electric vehicles. This paper proposes an electric vehicle charging station location model to improve the resource utilization of electric vehicles for sustainable cities. In this model, reservation services, idle rates during off-peak periods, and waiting time during peak periods are considered. Finally, a case from Chengdu, China, is used to examine the effectiveness of the proposed model. Then, further analyses of reservation ratios and penetration rates are conducted. The results show that the introduction of a reservation service has a positive effect on reducing the total cost, which would provide further support for sustainable cities and have an even greater impact on healthier lives.

Integrating Urban Adolescent Mental Health Into Urban Sustainability Collective Action: An Application of Shiffman & Smith's Framework for Global Health Prioritization

The majority (55%) of the world's population lives in urban environments. Of relevance to global mental health, the rapid growth in urban populations around the world and the attendant risks coincide with the presence of the largest population of adolescents the global community has seen to date. Recent reviews on the effects of the urban environment on mental health report a greater risk of depression, anxiety, and some psychotic disorders among urban dwellers. Increased risk for mental disorders is associated with concentrated poverty, low social capital, social segregation, and other social and environmental adversities that occur more frequently in cities. To address these problems, urban adolescent mental health requires attention from decision makers as well as advocates who seek to establish sustainable cities. We examine opportunities to increase the prominence of urban adolescent mental health on the global health and development agenda using Shiffman and Smith's framework for policy priorities, and we explore approaches to increasing its relevance for urban health and development policy communities. We conclude with suggestions for expanding the community of actors who guide the field and bridging the fields of mental health and urban development to meet urban adolescent mental health needs.

The energy for growing and maintaining cities

Herein we develop a means to differentiate between the energy required to expand and the energy required to maintain the economies of cities. A nonlinear model is tested against historical data for two cities, Hong Kong and Singapore. A robust fit is obtained for Hong Kong, with energy for maintenance close to that for growth, while Singapore, with a weaker fit, is growth dominated. The findings suggest that decreases in either of the per unit maintenance or growth demands can simultaneously cause gross domestic product (GDP) and total energy use to increase. Furthermore, increasing maintenance demands can significantly limit growth in energy demand and GDP. Thus, the low maintenance demands for Hong Kong, and especially Singapore, imply that, all other things being equal, GDP and energy use of these cities will continue to grow, though Singapore's higher energy use for growth means it will require more energy than Hong Kong.