Introduction
Analysis of the Green City Knowledge Map using the VOSviewer tool identifies research gaps in this field. The results of these analyses show that while most studies address environmental and land-use issues, the social, cultural, and economic dimensions of the green city have not been adequately addressed. This gap underscores the need for more comprehensive research to establish the necessary balance among the different dimensions of sustainable development. VOSviewer also highlights that most studies in this field have been conducted in Western countries and in English, and studies in developing regions with different cultural and climatic conditions are not sufficiently available. This geographical imbalance in knowledge production can lead to incorrect generalizations and inappropriate policy design in regions with different conditions. Therefore, this is considered a major research gap in the field of green cities. Finally, the results of the green city knowledge maps using VOSviewer show that the connections between different knowledge areas (such as architecture, urban planning, environment, urban economics, etc.) are not yet well established. This points to the need for interdisciplinary, integrated research to address the complex challenges of today's cities with a comprehensive approach. Therefore, identifying these gaps can be a basis for guiding the future of green city research.
Theoretical framework
Green cities are defined as cities that strive to reduce their environmental impact by reducing waste, expanding recycling, reducing greenhouse gas emissions, increasing housing density while expanding open space, and encouraging the development of sustainable local businesses. A green city is one in which all forms of nature – living organisms, their ecosystems, and habitats – are vital components of its green infrastructure. In a green city, these forms of nature are preserved, maintained, and expanded for the benefit of the city’s residents. Urban nature is an ideal provider of services and a key concept for city development. Green cities have clean air and water, and pleasant streets and parks. Green cities are resilient in the face of natural disasters, and the risk of major infectious diseases spreading in such cities is low. Green cities also encourage green behaviors, such as using public transportation, and have a relatively low ecological impact.
Methodology
The present study is a mixed-methods study with an applied purpose and was conducted using a scientometric method based on the analysis of co-authorship and word co-occurrence. The study's statistical population comprises scientific, conference, and book publications by global authors in English on the green city paradigm published between 1979 and 2025. The sources of the statistical population of the present study are indexed in the Scopus scientific database. The reason for using the Scopus database is that it has more comprehensive resources than Web of Science and provides access to a larger number of resources. VOSviewer software was used to visualize the network of co-authorship and co-occurrence of words, as it was developed for the construction and visualization of bibliometric maps, and its graphical displays effectively depict the network. An advanced search for the term 'green city paradigm' in the Scopus database, without restrictions on title, abstract, or keywords, identified 1587 references between 1979 and 2025. The highest frequency of references is from 2024 (236 references). It is worth noting that the basis of the co-authorship network is 4. The basis of the co-occurrence network of terms is 5. In addition, the dimensions, components, and indicators of the green city were extracted through interviews with 15 experts.
Result and discussion
The Green City Paradigm co-authorship network comprises 121 co-authors and researchers, organized into 8 clusters. Based on the co-occurrence network, the most frequent green city words consist of China (248), sustainable development (225), urban planning (172), green space (166), urban area (161), sustainability (140), urban development (94), human (86), climate change (82), ecology (80), urbanization (74), smart city (72), urban growth (72), decision-making (66), green infrastructure (62), innovation (58), biodiversity (56), economic development (54), environmental protection (52), optimization (49), green economy (48), urban design (47), carbon (44), ecosystem services (43), land use (43), accounting Green (43), carbon emissions (42) and energy efficiency (41). The time course of the evolution of green city concepts and terms has been classified into five stages, including 2016-1979; 2016-2018; 2020-2018; 2022-2020; and 2025-2022. As a result, since 2025-2022, more attention has been paid to green attitude, green economy, green purchase intention, carbon emissions, efficiency, building information modeling, water, economic development, urban regeneration, green finance, green innovation, green logistics, green production, green technology, green technology innovation, sustainable development goals, consumption behavior, theory of planned behavior, social responsibility and overall green factor efficiency.
Conclusion
The results of the study indicate that research in this field has gradually moved from traditional urban management approaches to innovative, ecological, and participatory frameworks. The knowledge map drawn with VOSviewer identified commonalities and interactions across scientific disciplines such as geography, environment, urban planning, architecture, and the social sciences, and revealed numerous research networks centered on concepts such as "zero carbon," "resilient cities," and "public green spaces." Also, the analysis of keywords and scientific references showed that the green city paradigm is influenced by global trends, including climate change, sustainable development, and the Millennium Development Goals. In summary, the green city, as a new urban planning paradigm, is not only an innovative response to the environmental and social challenges of today's cities, but also paves the way for the realization of sustainable development at the local and national levels. Awareness of the existing knowledge base in this field can be a key to identifying research gaps, strengthening interdisciplinary collaborations, and informing urban planning policies. Therefore, continuing qualitative and quantitative studies in this field using knowledge extraction tools such as VOSviewer seems essential.