Identification of Strategies and Mechanisms for Achieving Zero-Carbon Cities: A Qualitative Meta-Analysis

1. Introduction

In recent decades, climate change and the increase in greenhouse gas emissions have emerged as one of the greatest global challenges. Cities, as the largest consumers of energy and resources, play a key role in either exacerbating or mitigating this phenomenon. Despite numerous efforts to achieve low-carbon and even carbon-free cities, the central question remains: what strategies and mechanisms can effectively lead to the realization of these goals? The importance of this issue becomes more apparent when considering that cities account for approximately 70% of global greenhouse gas emissions. This research aims to identify patterns, trends, and key mechanisms in achieving carbon-free cities through a systematic review of existing literature. The necessity of this study lies in the fact that, despite a significant volume of research on sustainable cities, there are still gaps in understanding and operationalizing strategies for achieving carbon-free cities. This paper, using a meta-analysis approach, seeks to answer the question of which factors (technical, managerial, social, and structural) act as the main drivers in realizing carbon-free cities. Ultimately, the present study provides a comprehensive theoretical framework to guide planners and policymakers in designing and implementing sustainable carbon-free cities.



2. Research Methodology

This research employs a meta-analysis approach to systematically review and evaluate existing studies on carbon-free cities. The PRISMA framework was used to ensure transparency and reproducibility, consisting of four main stages: identification, screening, eligibility assessment, and inclusion of sources. In the identification stage, a systematic search was conducted in reputable scientific databases such as Elsevier, Springer, Emerald, Wiley, Sage, and ResearchGate. A set of keywords, including "decarbonization," "post-carbon city," "low-carbon economy," and "low-carbon transition," was used, initially identifying 412 sources. After removing duplicates and irrelevant sources, 37 sources were selected for final analysis. Inclusion criteria consisted of sources directly addressing carbon-free cities and published in reputable journals or publications. Exclusion criteria included lack of access to full texts, lack of scientific credibility of authors, or high overlap with the research topic. In the data extraction stage, relevant information regarding the type of research, data collection methods, and key findings was extracted from each source. Subsequently, open coding was used to identify 128 open codes, which were then categorized into eight selective codes and 39 axial codes. Finally, content analysis and comparative methods were employed to identify patterns and trends.

3. Results and discussion

Data analysis revealed that the majority of sources were published in 2022 and 2023 (46%), with qualitative studies comprising 60% of the total. A total of 128 open codes, eight selective codes, and 39 axial codes were extracted, highlighting the importance of factors such as energy consumption reduction, waste management, urban forestry, and science and technology in achieving carbon-free cities. Temporal analysis showed a shift in research focus from general concepts like decarbonization to more specific ones such as smart low-carbon cities and circular economies. In terms of code frequency, codes related to buildings, energy, and urban transportation had the highest number of open codes, underscoring their significance. Pattern analysis indicated that the majority of open codes focused on reducing energy consumption, waste management, and urban forestry. Axial codes emphasized the critical role of science and technology, resources and environment, and economy and industry. Trend analysis from 1990–2003 to the present revealed a shift from general concepts like decarbonization to more specific ones such as carbon-free cities and circular economies. Comparative analysis among countries showed that developed nations focused more on advanced technologies and R&D investment, while developing countries emphasized waste management and climate adaptation. These findings provide a comprehensive understanding of the mechanisms driving carbon-free cities.

4. Conclusion

The findings indicate that achieving carbon-free cities requires the integration of social, economic, and environmental dimensions. Key strategies include reducing carbon emissions, improving energy efficiency, developing sustainable infrastructure, and promoting low-carbon lifestyles. These findings address the main research question by identifying strategies and mechanisms for achieving carbon-free cities. To this end, a theoretical model was developed, emphasizing internal drivers (science and technology, resources and environment, economy and industry) and external drivers (facilities, capital, and institutional conditions). This model offers a comprehensive framework for planning and operationalizing carbon-free cities. The theoretical implications include filling existing gaps in the literature and providing a holistic framework for understanding the mechanisms of carbon-free city realization. Practically, these findings can guide policymakers and planners in designing and implementing sustainable carbon-free cities. Recommendations include developing context-specific strategies for different regions, strengthening institutional and technological capacities, and promoting community participation in carbon reduction efforts. Additionally, future research is encouraged to explore local and regional factors influencing carbon-free city achievement and conduct comparative analyses between developed and developing countries.