A GIS-based multicriteria decision analysis (MCDA) is presented to evaluate the suitability of land for the implementation of nature-based solutions (NbS) to enhance carbon sequestration in Emilia-Romagna, Italy. Excessive carbon emissions into the atmosphere have caused rapid and profound climate change that needs to be mitigated. The use of NbS has emerged as an effective strategy to sequester atmospheric carbon and improve environmental resilience. This study focuses on identifying the best NbS to maximise carbon sequestration for three environmental zones: urban, peri-urban and agricultural. The analysis identifies optimal locations for three area-specific NbS: street trees, green spaces and buffer strips. The region was divided into 30 × 30 m grid pixels, with each grid cell assigned a value from 1 (least suitable) to 5 (most suitable). The results show that most of the high-quality pixels are located near the main urban centres and along the coastline. These results provide useful information for policy makers and urban planners who can be guided in the strategic implementation of NbS to achieve maximum environmental benefits. The work also includes an individual sensitivity analysis to validate the robustness of the proposed model and a quantitative estimate of the carbon that can be sequestered by these NbS.

Artificial intelligence (AI) has become a transformative force across various disciplines, including urban planning. It has unprecedented potential to address complex challenges. An essential task is to facilitate informed decision making regarding the integration of constantly evolving AI analytics into planning research and practice. This paper presents a review of how AI methods are applied in urban studies, focusing particularly on carbon neutrality planning. We highlight how AI is already being used to generate new scientific knowledge on the interactions between human activities and nature. We consider the conditions in which the advantages of AI-enabled urban studies can positively influence decision-making outcomes. We also consider the importance of interdisciplinary collaboration, responsible AI governance, and community engagement in guiding data-driven methods and suggest how AI can contribute to supporting carbon-neutrality goals.

Carbon sequestration and storage are vital in complementing the reduction of anthropogenic greenhouse gas (GHG) emissions to mitigate climate change. Globally, forests are recognized for their significant carbon sequestration and storage potential, serving as a natural solution to climate change. This study examines the temporal dynamics of carbon sequestration in the forests of Stockholm County, Sweden, focusing on tree species composition, forest age, and local hydroclimatic conditions. The research underscores the variability in sequestration capacity across different forest types and ages, with middle-aged forests identified as key contributors to carbon capture. Projections indicate a 27% increase in sequestration potential by 2040, driven by natural forest aging and expansion, provided current forest management practices are maintained. However, this potential increase may be influenced by land use change, climate change impacts, and forest management strategies. Effective forest management is important to enhance and sustain carbon sequestration capacities, aiding Stockholm County in achieving its net zero emissions goal by 2040. Further research is necessary to refine sequestration estimates and optimize forest management practices for long-term climate mitigation.

This study investigates the spread of innovative behavioral (green nudging) policies within city-level Climate Action Plans (CAPs) across the European Union, focusing on how these innovations diffuse and the factors influencing their adoption. Using textual analysis with a dataset consisting of CAPs from 40 cities across Europe, we categorized various green nudging innovations and then tracked their origins and uptake. Then, we employed fsQCA (Fuzzy set qualitative comparative analysis) to identify the key factors driving diffusion. The findings reveal that while certain innovations, particularly in the building and transportation sectors, have achieved widespread adoption, other initiatives like community co-creation and urban parks have seen lower diffusion. Local terrestrial factors, especially sectoral carbon emissions, are significant drivers, with cities facing higher emissions more likely to adopt these policies. Interestingly, local emissions levels and strong climate leadership emerge as more critical determinants than economic status or climate similarities. The study identifies two primary diffusion pathways—Cultural Leadership for Emission Reduction and Local Adaptive Synergy—demonstrating the diverse strategies cities employ based on their unique contexts. This research highlights the importance of expanding green nudging measures in CAPs beyond technological and infrastructure domains to promote low-carbon behaviors comprehensively.

Nature-based solutions (NBS) are essential for carbon-neutral cities, yet how to effectively allocate them remains a question. Carbon neutrality requires city-led climate action plans that incorporate both indirect and direct contributions of NBS. Here we assessed the carbon emissions mitigation potential of NBS in European cities, focusing particularly on commonly overlooked indirect pathways, for example, human behavioural interventions and resource savings. Assuming maximum theoretical implementation, NBS in the residential, transport and industrial sectors could reduce urban carbon emissions by up to 25%. Spatially prioritizing different types of NBS in 54 major European Union cities could reduce anthropogenic carbon emissions by on average 17.4%. Coupling NBS with other existing measures in Representative Concentration Pathway scenarios could reduce total carbon emissions by 57.3% in 2030, with both indirect pathways and sequestration. Our results indicate that carbon neutrality will be near for some pioneering cities by 2030, while three can achieve it completely. Effective spatial allocation of the nature-based solutions is important for city mitigation through various pathways. This Analysis allocates prioritized urban nature-based solutions to major European cities and estimates their potential contribution to emission reductions, then the carbon neutrality targets.

Nature-based solutions (NbS) are recognized as widely available and cost-effective mechanisms for sequestering carbon and offsetting carbon emissions. Realistic NbS implementations for carbon neutrality need to be effective at the global level and also appropriate for the socio-economic and physical conditions prevailing at the local level. This paper presents a framework that can help stakeholders identify demands, locations, and types of NbS interventions that could maximize NbS benefits at the local scale. Key processes in the framework include (1) interpolating carbon emissions data at larger spatial scales to high-resolution cells, using land use and socio-economic data; (2) assessing NbS effects on carbon reduction and their location-related suitability, through qualitative literature review, and (3) spatially allocating and coupling multiple NbS interventions to land use cells. The system was tested in Stockholm, Sweden. The findings show that the urban center should be allocated with combinations of improving access to green spaces and streetscapes, while the rural and suburban areas should prioritize preserving and utilizing natural areas. Our proposed method framework can help planners better select target locations for intended risk/hazard-mitigating interventions.

To accommodate a growing global population while mitigating climate change, urban areas must grow while minimising environmental impacts. To achieve this, a city must be treated as a complex socio-ecological system in which many actors and subsystems act in unclear and unpredictable ways. This thesis explores the workings and interactions of this complex socio-ecological system by assessing how urban and regional planning and policy decisions affect the contributions of cities to climate change, and whether appropriate planning and policy tools can minimise these contributions. Computer models were developed to investigate and couple planning and policy decisions and their potential impacts on the environment, particularly in terms of greenhouse gas (GHG) emissions to the atmosphere. The models were then employed for generation of scientific knowledge and for converting this knowledge into practical planning tools and recommendations.

Methods used in developing models that reflect complex urban systems included cooperation with experienced county planners to improve model accuracy; coupling of sub-system models in a socio-ecological framework for scenario analysis of the outcomes of planning and policy decisions in terms of GHG emissions; systems breakdown analysis of green-blue contributions to the urban carbon cycle; and modelling to identify how these contributions could be harnessed to reduce net urban emissions. The main study area was Stockholm County, Sweden, with later extension of the modelling approach to 54 major European cities. 

Cooperation with Stockholm County planners during model development resulted in an improved tool for scientific research that was also suited to practical planning, increasing the potential for knowledge developed through scientific research to be applied in reality. Scenario analysis of policies for Stockholm County revealed that zoning reduced the extra GHG emissions associated with necessary urban growth by 72% compared with a baseline scenario. Analysis of the urban carbon cycle in Stockholm County showed that vegetative carbon sequestration helped offset GHG emissions locally, but that re-emissions via surface waters compromised the potential to reach ‘net-zero’ emissions from Stockholm County. However, climate action goals for Stockholm could still be achieved if its ambitious emissions reduction plans are realised and if the current sequestration capacity of Stockholm County’s many green areas can be maintained in coming decades.

 Extensive modelling of urban emissions in multiple European cities showed potential for green-space sequestration and revealed that nature-based solutions (NbS) applied at city scale could help reduce urban emissions. Incorporation of NbS into climate action plans for these cities would maximise the associated GHG emissions reduction and increase the likelihood of the cities achieving their climate action goals. 

In conclusion, the climate change impacts of future urban expansion could be mitigated by incorporating planning and policy tools such as zoning, protection of green-blue spaces and NbS into whole-system urban and regional development plans. This could bring cities closer to achieving truly sustainable urban development.

The first mile/last mile (FM/LM) problem in public transport refers to the spatial accessibility of public transport and is the most important factor determining whether an individual will choose public transport. The FM/LM problem in Stockholm County, Sweden, was evaluated using a Geographic Information System estimating distances to public transport for the years 2019 and 2035. Overall, the population in Stockholm County, have good access to public transport. However, access varies with abilities, with elderly having 50 percent and elderly impaired 15 percent of their area within walking distance to public transport compared with the average citizen. Planned developments can provide good access to public transport, with extensive improvements for the elderly. However, inadequate planning for population increase will likely decrease the perceived public transport accessibility. Apartments and commercial buildings in the study area have high access to public transport. Elderly people have good access within city and regional centers, while access could be improved in other areas. Inclusion of FM/LM in the planning support system used in Stockholm could help mitigate FM/LM problems and extend access to public transport to all people of different abilities. This is vital in creating sustainable mobility networks and achieving sustainable development in smart cities. 

Understanding interactions between complex human and natural systems involved in urban carbon cycling is important when balancing the dual goals of urban development to accommodate a growing population, while also achieving urban carbon neutrality. This study develops a systems breakdown accounting method to assess the urban carbon cycle. The method facilitates greater understanding of the complex interactions within and between systems involved in this cycle, in order to identify ways in which humans can adapt their interactions to reduce net greenhouse gas emissions from urban regions. Testing the systems breakdown accounting method in Stockholm County, Sweden, we find that it provides new insights into the carbon interactions with urban green-blue areas in the region. Results show how Stockholm County can reduce its emissions and achieve its goal of local carbon net-neutrality, if the green areas protect its carbon sequestration potential and maintain it to offset projected remaining active emissions. Results also show that the inland surface waters and inner archipelago waters within Stockholm County are a considerable source of greenhouse gases to the atmosphere. A better understanding of these water emissions is necessary to formulate effective planning and policy measures that can reduce urban emissions. The insights gained from this study can also be applied in other regions. In particular, water bodies could play a significant role in the urban carbon cycle and using this knowledge for more complete carbon accounting, and a better understanding of green-blue interactions could help to reduce net urban emissions in many places.

Addressing urban challenges with nature-based approaches can improve and protect ecosystem services. Yet, urban planning has not efficiently integrated such approaches to manage land use. This paper examines interactions between human and natural systems that result in ecosystem services and changes in land use and land cover in urban areas. It develops a social-ecological model for land use and land cover change, and for ecosystems services that integrates nature-based solutions in urban planning. The model treats spatial variations in ecosystems services as both drivers and consequences of human decision-making in choosing commercial and residential locations that drive land use and land cover change. We tested the social-ecological model in Stockholm County, Sweden, on a 30 x 30 m grid. Results show that accessibility in ecosystem services drives urban residential and commercial development, characterized by non-linearity. Areas around existing urban centers show high accessibility in ecosystem services and high development probabilities, whereas smaller population centers in large areas enjoy high accessibility to ecosystem services and low urban development probabilities. Model results suggest place-specific nature-based strategies for addressing the heterogeneous spatial relationships between ecosystem services and urban development.