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City systems are characterized by the functional organization of cities on a regional or country scale. While there is a relatively good empirical and theoretical understanding of city size distributions, insights about their spatial organization remain on a conceptual level. Here, we analyze empirically the correlations between the sizes of cities (in terms of area) across long distances. Therefore, we (i) define city clusters, (ii) obtain the neighborhood network from Voronoi cells, and (iii) apply a fluctuation analysis along all shortest paths. We find that most European countries exhibit long-range correlations but in several cases these are anti-correlations. In an analogous way, we study a model inspired by Central Places Theory and find that it leads to positive long-range correlations, unless there is strong additional spatial disorder - contrary to intuition. We conclude that the interactions between cities extend over large distances reaching the country scale. Our findings have policy relevance as urban development or decline can affect cities at a considerable distance.
As we are still not on track to achieve environmental sustainability through technological change, we need to further stress the importance of understanding routinized types of behaviour by private households and the environmental assessment of corresponding consumption of resources. Social practice theories allow us to understand the constitution of human activity and its embeddedness in society. In transformation research, the relevance of social practice theories has been recognized. However, there is still a lack of understanding regarding the conditions under which practices change substantially and what kinds of tools and governance approaches are suitable to foster change in social practices. We therefore propose a novel way to address the transformation of consumption patterns of private households by a) connecting social practice theories to life cycle assessment for a quantitative environmental evaluation of transformation processes and b) using narrative approaches to understand the links between several social practices and conditions for change. An illustrative study of a bottom-up neighbourhood initiative shows how specific meanings and values (expressed, for example, through meanings of “enough”) affect several social practices from different consumption categories (nutrition, daily mobility, travelling). Environmental assessments further show that changing social practices across consumption categories can substantially decrease environmental pressures from private household consumption, especially in the field of nutrition. The understanding of how various social practices are connected in a nexus through narratives embodying deeper meanings point to novel ways of fostering change and the relevance of social practices related to urban or neighbourhood initiatives as an entry point to a more sustainable way of living.
Born circular startups play a pivotal role in implementing high-level circularity to fight resource depletion and address climate change. In developing circular business model innovation, circular startups face the challenge of lacking legitimacy, which can be approached by certifications provided by concepts like Cradle-to-Cradle. As there is currently no supporting tool to develop such business models, this paper employs a design science research approach and proposes a Cradle-to-Cradle (C2C) Business Model Tool. The tool is developed based on a literature review, feedback from 42 users in six demonstration workshops and is finally tested with eight startups. It succeeds in aiding born circular startups in navigating the venturing process with a focus on high-level circularity. In this paper, C2C principles developed for the product level are theoretically linked to the business model level. The tool addresses elements such as partnerships, communication, and action-taking, thereby contributing to the literature on circular business model innovation and serving as a practical resource for born circular startups.
Aiming at setting up a global platform for e-mobility solutions, the EU-funded project SOLUTIONSplus (2020-2023) established nine living labs in Africa, Asia, Europe, and Latin America to test innovative solutions involving new services, business models, vehicle types, and charging systems. A user needs analysis was undertaken in all project cities. The paper summarizes the main findings of this analysis and investigates the effect of the external environment on user needs. The perceived importance of electric vehicles in mobility patterns, quality of life, and city environment is examined, along with expected challenges in the respective market penetration. It is found that these perceptions are correlated with external factors such as air pollution or traffic congestion, leading to possible adjustments of the e-mobility promoting efforts according to the local stakeholder priorities.
Background: National energy and climate scenarios are typically simulated or optimised using sectoral or energy system models, which include a large number of model settings and scenario assumptions. However, their realisation is contingent upon framework conditions and policy settings, which are often included in accompanying narrative scenarios. This paper therefore proposes refocussing the model-policy logic towards directly modelling policy effects. Applying this approach to the case of German passenger transport, I focus on demand-side policies and use open-source databases and models to develop a module for the translation of policies into model parameters.
Results: Separate model runs were used to test a ceteris paribus policy reference scenario for 2035, the marginal impacts of modelled single policy effects, and a joint policy package scenario. Relative to the reference, demand-side policies show significant impacts: an annual reduction of 355 bn person-kilometres (30%) and a reduction of car-owning households from 95 to 90% in rural areas and from 76 to 64% in urban areas. The resulting mode shift decreases car-driven kilometres by 400 bn and increases public transport by 45 bn per year. This may reduce GHG emissions by an additional 30 Mt (or 33%) relative to the reference in 2035.
Conclusions: Transport demand policies can significantly mitigate GHG, calling for a stronger policy focus beyond the much-studied shift to electric vehicles. While further research and model development are needed, the feasibility of policy scenario modelling increases its utility for policy-making.
The implementation of the circular economy is crucial to combat climate change especially in energy- and carbon-intensive sectors like the steel industry. It requires the environmental assessment of circular interventions to steel products to ensure that they are in line with targets of the circular economy - increase of resource efficiency and sustainability. Based on previous case studies and established methodologies, an environmental assessment framework is suggested and applied. It comprises a Material Flow Analysis to quantify selected mass-based indicators to evaluate the parameters of circular economy, as well as a Life Cycle Assessment to quantify the difference of the environmental impact. The application to a case study in the metalworking industries shows that the implementation of repurposing to a machining knife and hand tools contributes to all circular economy strategies - narrowing, slowing, and closing. At first, however, the circular intervention did not lead to a reduction of the environmental impact. It was found that the optimization of share of secondary material, energy mix, grinding, and transportation can lower the environmental impact of the circular compared to the conventional product system. Considering the increased product functionality, the environmental performance of the circular product system is superior. The study shows the importance of integrating assessment methods covering the resource level and environmental sustainability since focusing only on the resource efficiency can be misleading. At the same time, it stresses the need to apply environmental assessments in the product development stage to design environmentally sustainable and resource-efficient product systems.
In this perspective paper, we propose to integrate the concepts of Mobility-as-a-Feature (MaaF, an extension of MaaS) and the 15-minute city (15mC). The 15mC concept maintains that daily necessities and services, such as shopping, healthcare, and leisure should be accessible without private cars within 15 minute. In line with MaaF, these services could be integrated with a variety of mobility options into a single app. This novel approach is poised to offer a seamless customer experience, better resource utilization, enhanced urban mobility, improved and more inclusive access to services, and greater community connectivity. We call them local super apps: a new model to drive equitable and sustainable urban transitions. We substantiate this preliminary idea with evidence from literature, practical applications, and a user survey (N = 1,019), while also discussing future research avenues to further develop the concept of local super apps.
Over 175 million Nigerians rely on the use of traditional biomass for cooking, and it is estimated that more than 128,000 people died in Nigeria in 2019 from household air pollution related to these fuels. There is currently a gap in the study of possible pathways to meet Nigeria's goals in clean cooking and in understanding the health and climate impacts that different pathways can bring about. We explore clean cooking access scenarios for Nigeria until 2060 under a business-as-usual scenario, a moderate climate mitigation scenario, and an ambitious transformative scenario. We carry out a disaggregation at the state level for the period up to 2030 to better guide shorter-term policy development. Our analysis shows that under an ambitious scenario where 85 million households achieve access to clean cooking by 2060, annual premature deaths due to exposure to household air pollution would decrease by 7 % compared to 2018 levels. A baseline scenario, on the other hand, sees a dramatic 77 % increase, resulting in 209,000 people dying prematurely, of which 94,000 children under 5. Furthermore, we find that woodfuel removals from forestland would lead to a tripling of carbon dioxide emissions from land use change, reaching 602 Mt CO2 by 2060. Our findings stress the vital importance of a clean cooking transition in Nigeria and underline the urgent need for immediate acceleration in national efforts regarding access to clean cooking for all.
The global building sector, responsible for over 30% of CO2 emissions, necessitates urgent decarbonization efforts. This paper examines residential building decarbonization policies in three major economies - the European Union (EU), China, and India. It provides an overview of diverse policies through policy landscape analysis and delves into the design specifics with a detailed policy intensity analysis of building energy codes, information disclosure, and financial incentives in each region. Our findings reveal a diverse mix of policies targeting residential building decarbonization in all three regions. While the EU and China have long-established diverse policy instruments, India's building energy efficiency policies are relatively recent and limited. Detailed analyses of building energy codes, information disclosure, and financial incentives expose variations in ambition, scope, and implementation, even with shared policy instruments. Significant advancements in building energy codes, particularly in stringency and compliance checks, are evident in the EU and China. Conversely, India faces a notable obstacle with limited adoption of residential building energy codes, impacting its journey towards net-zero. The EU leads in building energy labelling policies, while China and India encounter various challenges hindering widespread implementation. Financial incentives across the three regions predominantly take the form of subsidies, potentially straining public budgets. The study concludes with reflections on the pressing need for future research extending beyond the operational phase of buildings.
In Germany, there are over 32,000 schools, representing great potential for climate protection. On the one hand, this applies to educational work, as understanding the effects of climate change and measures to reduce GHG emissions is an important step to empower students with knowledge and skills. On the other hand, school buildings are often in bad condition, energy is wasted, and the possibilities for using renewable energies are hardly used. In our "Schools4Future" project, we enabled students and teachers to draw up their own CO2 balances, identify weaknesses in the building, detect wasted electricity, and determine the potential for using renewable energies. Emissions from the school cafeteria, school trips, and paper consumption could also be identified. The fact that the data can be collected by the students themselves provides increased awareness of the contribution made to the climate balance by the various school areas. The most climate-friendly school emits 297 kg whilst the school with the highest emissions emits over one ton CO2 per student and year. Our approach is suitable to qualify students in the sense of citizen science, carry out a scientific investigation, experience self-efficacy through one's own actions, and engage politically regarding their concerns.
