The Impact of Green Infrastructure on Mitigating Urban Heat Island Effect: Current Status, Trends, and Challenges

Abstract

In the context of global climate change and rapid urbanization, the urban heat island (UHI) effect has emerged as a critical issue impacting urban sustainability. This study analyzes 945 publications retrieved from the Web of Science Core Collection (2000–2025) and employs VOSviewer and Scimago Graphica to construct and visualize a knowledge map. The findings indicate that, since 2013, there has been a significant increase in research interest in utilizing green infrastructure (GI) to mitigate UHI, with China, the United States, and Europe leading international collaboration efforts. Keyword analysis reveals that early studies primarily focused on thermodynamic manifestations. Recent research has shifted toward more diverse topics, including artificial neural networks (ANNs), environmental justice, and public participation. By constructing a knowledge framework, this study clarifies how GI mitigates UHI while simultaneously promoting carbon reduction, enhancing health benefits, and supporting resilient governance. This research provides a comprehensive overview of the role of GI in mitigating UHI, offering theoretical insights and practical solutions for achieving integrated governance that combines climate resilience, biodiversity conservation, and social equity. These findings have significant theoretical and practical implications for advancing both UHI mitigation and sustainable development.

1. Introduction

Cities, as epicenters of human civilization, play a crucial role in societal advancement [1]. These regions concentrate the majority of the world’s economic activities, innovative resources, and infrastructure, generating approximately 80% of global GDP and profoundly influencing the trajectory of modern societal development [2]. According to the United Nations Department of Economic and Social Affairs’ 2018 Revision of the World Urbanization Prospects report, the global urban population is projected to increase by 2.5 billion by 2050, resulting in 68% of the world’s population living in urban areas [3]. However, the rapid pace of urbanization and intensified human activities have led to a gradual rise in global urban temperatures, disrupting the local energy balance and giving rise to the UHI effect [4]. This phenomenon poses significant threats to public health and urban ecosystems, resulting in substantial economic losses [5,6,7]. Currently, the UHI effect poses a significant global challenge [8]. This issue is especially pronounced in developing countries, where urbanization is progressing rapidly [9]. Such accelerated urbanization is expected to exacerbate both the UHI effect and global warming, resulting in an increase in heat-related illnesses and fatalities [10,11,12]. A study by Vicedo-Cabrera et al. (2021), utilizing empirical data from 732 locations across 43 countries/regions, found that, over a 27-year period from 1991 to 2018, human-induced climate change accounted for 37% of deaths related to warm-season high temperatures [13,14]. Urban areas are warming at a significantly faster rate than rural regions due to human activities and alterations in land surface environments. Addressing this challenge necessitates the urgent formulation of effective strategies to mitigate the UHI effect [15].

Benedict and MacMahon introduced GI in 2012 as a conceptual framework for systematic planning that prioritizes the preservation of ecosystem services through interconnected natural ecological networks [16]. A significant policy milestone was reached in 2013 with the adoption of the European Union’s “GI Strategy [17,18],” which sparked a surge in international research and practice. In 2021, the Singaporean government unveiled the “Singapore Green Plan 2030,” setting development objectives for the coming decade [19]. This plan mandates the creation of over 130 hectares of new parks by the end of 2026 and requires that 80% of new constructions meet ultra-low energy consumption standards starting in 2030. “Extreme heat is having extreme effects on humanity and the planet, and the world must act urgently to address the challenge of rising temperatures,” stated UN Secretary-General António Guterres during a press conference on 5 July 2024, at the UN headquarters in New York. The European Ecological Restoration Law, passed that same year, further integrated GI into a framework for mandated urban ecological restoration, providing new policy impetus for related research [20]. Biodiversity conservation is one of the primary objectives of GI, which has been recognized as a crucial instrument for enhancing urban biodiversity by the Kunming-Montreal Global Biodiversity Framework (COP15) [21]. Its ecological value is increasingly acknowledged; for example, urban forests and wetlands enhance ecosystem resilience by providing habitat for various species and mitigating the heat island effect [22].

Currently, the academic community has conducted extensive research on the causes and impacts of the UHI effect and has proposed a variety of mitigation measures [23,24,25]. For instance, the 1995 Chicago heatwave underscored the potential dangers of urban heat. Research conducted by Patz et al. (2005) examined existing evidence, indicating that global warming has led to increased diseases and premature deaths worldwide, potentially having profound impacts on human health [26]. Feyisa et al. (2014) analyzed 21 parks in Addis Ababa and found that parks with a greater diversity of tree species exhibited the highest cooling effects [27]. Li et al. (2024) [28] utilized remote sensing data to quantify the cooling effects of urban greening in 500 major cities worldwide during warm-season daytime, discovering that northern cities experienced a 142.86% greater cooling effect compared to southern cities. This disparity arises from differences in the quantity and quality of GI between these regions [28]. Eyni et al. (2025) found that more costly mitigation strategies often significantly reduce heat-related mortality but are not the most effective in decreasing mortality inequality under extreme climate conditions [29]. Building upon these studies, this research focuses on developments since 2000, examining the role of GI in mitigating the UHI effect. It holds significant theoretical and practical implications for alleviating the UHI effect and achieving sustainable urban development.

Although GI has been extensively studied as a solution to the UHI effect, existing research primarily focuses on specific issues related to UHI [30,31,32,33]. These issues include the impact of global warming on human health, the cooling effects of urban GI, the effectiveness of GI in mitigating UHI, the influence of emission reduction pathways on mortality under extreme climate conditions, and equity concerns [34,35,36]. However, there is a notable lack of systematic knowledge synthesis and evolutionary analysis regarding the role of GI in mitigating UHI from a global perspective. Additionally, current reviews mainly emphasize the design principles and implementation strategies of GI, with limited multidimensional bibliometric analyses addressing the disciplinary framework, evolving research hotspots, key scientific questions, and future directions concerning GI’s role in mitigating UHI [37,38,39]. To address this gap, this study conducts a bibliometric analysis of 945 papers related to GI and UHI, published between 2000 and 2025 in the Web of Science Core Collection. This study provides a systematic review of the international status, research hotspots, and trends in the role of GI in mitigating UHI, offering guidance to researchers in this field and helping them gain a comprehensive understanding of research dynamics and future directions from various perspectives. Specifically, this study employs tools such as VOSviewer and Scimago Graphica for bibliometric analysis, which effectively handle large volumes of literature data and generate visual knowledge maps to identify research hotspots and trends. The main research objectives include the following:

• Systematic Literature Review and Knowledge Mapping: This paper provides a comprehensive analysis of the global research landscape on GI aimed at mitigating UHI effects. It examines various dimensions, including annual publication trends, geographical distribution, output by countries, institutions, and authors, as well as co-citation networks and keyword co-occurrence analysis. The objective is to offer scholars a systematic literature review, intuitive visual knowledge maps, and insights into the evolution of research trends.
• In-Depth Analysis of Research Hotspots: This study focuses on identifying key research hotspots from the perspectives of technological mechanisms and social governance. It elucidates the core issues in current research, the challenges encountered, and the evolving directions of technological approaches. The aim is to offer a broader range of methodological options for applying GI to mitigate UHI effects, as well as to provide valuable references for understanding the current state and future development of related technologies.
• Insights into Future Research Directions: This study aims to provide scholars with valuable theoretical guidance and practical insights to support further research in the field of GI for mitigating UHI effects, as well as promoting sustainable, resilient, and equitable urban development.

To the best of our knowledge, this comprehensive bibliometric study examines the role of GI in mitigating UHI, promoting urban carbon reduction, conserving biodiversity, and enhancing social equity governance, supplemented by targeted literature comparisons, thereby addressing a significant gap in existing reviews and bibliometric research. The research not only highlights emerging trends in international collaboration and interdisciplinary cooperation but also investigates critical frontier issues in urban sustainability, including blue-green infrastructure, ANNs, environmental justice, nature-based solutions (NBS), and urban microclimates. These findings provide a more systematic and forward-looking scientific foundation for promoting sustainable, resilient, and equitable urban development.

2. Materials and Methods

2.1. Data Sources and Retrieval Strategy

2.1.1. Data Source

This study utilized the Web of Science Core Collection database, provided by Clarivate Analytics. As one of the most widely used multidisciplinary literature retrieval tools globally, the WoS Core Collection encompasses a comprehensive range of academic disciplines, including natural sciences, social sciences, arts, and humanities. Renowned for its extensive data coverage, robust search functionalities, and timely updates, it serves as a reliable source for high-quality literature data in academic research.

2.1.2. Retrieval Strategy

To ensure the comprehensiveness and scientific rigor of the data, this study employed a precise Topic Search (TS) strategy. Multiple keyword combinations were utilized to encompass core research themes within the field. The search formula was as follows: TS = (“green infrastructure” OR “ecological infrastructure” OR “green facilities” OR “ecological facilities” OR “green projects” OR “ecological projects” OR “green building*” OR “ecological building*” OR “natural infrastructure” OR “green network*” OR “ecological network*” OR “green corridor*” OR “ecological corridor*” OR “stormwater management facilities” OR “blue-green infrastructure” OR “ecological landscape*” OR “green environmental facilities” OR “green roof*” OR “vegetated roof*” OR “natural roof*” OR “landscaped roof*” OR “planted roof*” OR “ecological covered roof*” OR “green covered roof*” OR “vegetation-covered roof*” OR “ecological greening roof*” OR “green building roof*” OR “ecological building roof*” OR “green roof layer*” OR “vegetation roof layer*” OR “ecological roof layer*” OR “green vegetated roof*” OR “ecological vegetated roof*” OR “rooftop garden*” OR “living roof*” OR “vertical greening” OR “vertical garden*” OR “green wall*” OR “ecological wall*” OR “plant wall*” OR “vertical greening building*” OR “vertical greening project*” OR “vertical greening landscape*”) AND (“Urban Heat Island*” OR “Urban Heat Island Effect*” OR “Urban Heat Island Phenomenon*” OR “Urban Heat Island Intensity*” OR “Urban Heat Island Effect Intensity*” OR “Urban Heat Island Effect Phenomenon*”).

Due to the dynamic nature of the Web of Science database, literature records may be updated, added, or deleted at any time. To ensure data consistency and avoid discrepancies arising from different time periods, we conducted the literature search on 25 March 2025. The time range was set from 1 January 2000 to 25 March 2025. The initial search yielded a total of 1190 documents; after limiting the language to English, the number of documents was reduced to 1179. Subsequently, we retained only Article and Review Article types, excluding Proceeding Papers (132), Early Access (3), Corrections (2), and Data Papers (1), resulting in 1093 candidate documents. To ensure the relevance and accuracy of the sample, the research team employed a manual screening method involving two independent reviewers, who eliminated documents with low relevance to the research topic based on their titles and abstracts. After consistency testing, 945 highly relevant documents were ultimately included in the analysis sample. This process strictly adheres to the PRISMA 2020 guidelines to ensure the authority of the data source and the scientific rigor of the analysis. The screening process is illustrated in Figure 1.

2.2. Data Processing and Analytical Methods

Bibliometric analysis is an interdisciplinary research method that integrates mathematics, statistics, and computer technology to quantitatively analyze and deeply mine scientific literature [40]. In this study, bibliometric methods, combined with advanced data analysis and visualization tools, were employed to systematically review and analyze the literature on the role of GI in mitigating UHI from 2000 to 2025.

The analytical framework of this study comprises several key dimensions: publication trends, geographic distribution, institutional collaboration, author contributions, journal impact, co-citation analysis, and keyword analysis. Its purpose is to reveal the current state of research, identify hot topics, and trace development trends within the field. To ensure that our findings are both systematic and visually intuitive, we utilized the following tools:

Microsoft Excel 2021: Used to organize raw data and calculate the annual publication count, thereby clarifying the developmental trends within the research field.

VOSviewer 1.6.20: Used to construct and visualize networks of author collaboration, institutional collaboration, and national collaboration, as well as keyword co-occurrence and cluster analysis. It represents the strength of collaborations and thematic relationships using color, node size, and line weight.

CiteSpace 6.4.R1: Used to perform reference co-citation analysis, create keyword temporal evolution maps (Timeline View), and conduct burst detection analysis to identify research hotspots, evolutionary paths, and emerging trends.

Scimago Graphica: Used to create maps showing national publication distributions, thereby enhancing the visual representation of geographic data and multivariate relationships.

Detailed parameters for all software tools and visualization settings are provided in the Supplementary Materials to ensure reproducibility.

3. Research Results

3.1. Analysis of Annual Publication Trends

The analysis of annual publication counts reveals the developmental trajectory of this research field. Figure 2 illustrates the yearly number of publications in this domain. Overall, the field has evolved from an initial exploratory stage to a period of rapid growth over the past two decades, exhibiting distinct phase-specific characteristics.

From 2003 to 2012, the field was in its infancy, with annual publication counts typically in the single digits and exhibiting minimal fluctuation. This pattern suggests that the topic had not yet garnered widespread scholarly interest. During this period, cumulative output increased gradually, reflecting a phase primarily focused on establishing theoretical foundations and conducting preliminary explorations.

Beginning in 2013, the number of publications increased steadily, rising from 13 papers in 2013 to 86 in 2020. This growth marks the establishment of GI as a key approach in UHI research. Between 2021 and 2024, annual output consistently exceeded 100 papers, reaching 124 publications in 2021 and climbing to 140 by 2024. This sustained high level of activity underscores both the continued attention to the topic and the vigorous productivity of research in this area. In summary, the past decade has exhibited a pronounced upward trend in annual publications, indicating that the intersection of GI and UHI effects has become a prominent focus within the broader field of urban sustainability research.

3.2. Geographic Distribution of Publications

The number of publications and their global citation counts serve as key indicators of a country’s scientific capacity and academic influence [41,42]. Figure 3 illustrates the geographic distribution of research outputs in this field by country and region.

To further elucidate international collaboration patterns in the field of GI aimed at mitigating UHI effects, this study employs VOSviewer to construct a national collaboration network map (see Figure 4). As illustrated in Figure 4, cooperation among countries exhibits distinct multi-center and clustering characteristics. Countries such as China, the United States, the United Kingdom, Italy, Australia, Germany, and India occupy central positions in scientific collaborations within this domain. China, characterized by the largest node size, demonstrates significant output and extensive international cooperation, forming close ties with nations like the United States, the United Kingdom, and Australia. The United States also serves as a major hub for international cooperation, maintaining frequent collaborations with several countries across Europe and Asia. European nations, including the United Kingdom, Italy, and Germany, display strong cooperation, often engaging in cross-continental collaborations with China and the United States. Additionally, Australia, Japan, Canada, and the Netherlands hold prominent positions in the international cooperation network, facilitating global academic resource sharing and technological exchange. Overall, the current collaboration network among countries not only reflects international trends in the field of GI for mitigating UHI but also underscores the collective efforts of the global academic community to address urban environmental and climate change challenges. This multi-center, high-density international collaboration model fosters the exchange and integration of knowledge, technology, and management experiences across diverse regions, promoting the global dissemination of cutting-edge theories and innovative findings. Furthermore, the leadership of developed countries, coupled with the participation of developing nations, ensures a balance between theoretical depth and practical application in research, thereby enhancing the diversity and applicability of outcomes. As the collaboration network continues to evolve, it is anticipated to achieve a higher level of global collaborative innovation, providing more robust scientific support for sustainable urban development and climate adaptation management.

3.3. Influential Authors

Analyzing author contributions offers valuable insights into the academic development of this field by identifying key researchers and their scholarly impact, as well as elucidating the collaborative networks among scholars [43].

Table 1. Top 10 authors by publication volume.

Rank	Author	NP	NC	AC	TC	H-Index (Wos)
1	Santamouris Mattheos	13	1484	114.15	28,940	87
2	Jim CY.	11	616	56.00	13,122	60
3	Pisello Anna Laura	8	636	79.50	9121	53
4	Osmond Paul	7	515	73.57	1742	19
5	Kolokotsa Denia	6	1099	183.17	798	13
6	Ng Edward	6	352	58.67	11,437	58
7	Wong Nyuk Hien	6	760	126.67	7859	46
8	Stephan Pauleit	6	495	82.5	9800	52
9	Gaffin, Stuart	6	110	18.3	3179	20
10	Lee, DongKun	6	91	15.1	2771	30

Note: NP = Number of Publications; NC = Number of Citations; AC = Average Citations per paper; TC = Total Citations (all publications). H-index = Hirsch index, measuring both productivity and citation impact.

presents the top ten authors ranked by publication volume.

According to the data analysis, Professor Mattheos Santamouris ranks first, with 13 related publications, significantly surpassing other authors. He also holds a commanding position in terms of cumulative total citations (28,940) and H-index (87), reflecting his international authority in this field. Currently, Professor Santamouris is affiliated with the University of New South Wales in Australia, having previously taught at the University of Athens in Greece and Kyung Hee University in South Korea. His research spans multiple disciplines, including energy, building technology, environmental science, and engineering, demonstrating notable interdisciplinary strengths. He has been recognized as a ‘highly cited scholar’ by Web of Science for several consecutive years and has published numerous high-impact papers on UHI, GI, and building environmental regulation. He is a leading figure in urban climate adaptation research.

Following closely are scholars such as Jim C.Y. and Pisello Anna Laura. Although they have published fewer papers than Professor Santamouris, their average citations (AC) and H-index demonstrate substantial research depth and academic influence. For instance, Pisello Anna Laura’s average citation count reached 79.50, reflecting her high recognition among peers. Furthermore, while Kolokotsa Denia’s average citation count (183.17) ranks first, her overall citation count is relatively low, suggesting that her research may be concentrated in a limited number of high-impact papers.

Overall, the research contributions of the top ten authors have established a crucial theoretical foundation and practical framework for the field. Most of these scholars focus on climate-resilient design, building energy efficiency, and environmental sustainability, indicating that research on GI to mitigate the UHI effect is increasingly coalescing into an academic community centered on the integration of the built environment and urban climate.

Analyzing author collaboration networks is crucial for understanding patterns of academic cooperation and the characteristics of research exchange within a specific field [44]. This study employs VOSviewer to visualize the author collaboration network in the domain of GI for UHI mitigation, as illustrated in Figure 5. In this network, each node represents an author, with the size of each node corresponding to the number of publications. The lines connecting the nodes indicate collaborative relationships, with the thickness of the lines reflecting the strength of cooperation. Different colors represent distinct collaborative clusters [45,46].

The overall network structure reveals relatively close collaborations among authors, forming several well-defined research groups. Notably, the red cluster, led by Satamouris Mattheos, stands out as one of the most active and stable collaborative networks in this field. This group includes collaborators such as Vasilakopoulou Konstantina, Garshasbi Samira, and Kolokotsa Dionysia, indicating a regional collaboration pattern centered around Greek research institutions. The strong internal connections and frequent academic interactions within this cluster have significantly contributed to knowledge accumulation in the field.

Similarly, the blue cluster, led by Pisello Anna Laura, exemplifies effective team collaboration. This group consists of researchers such as Cabeza Luisa F, Cháfer Marta, and Cristina Piselli, forming a European research team primarily based in Italy and Spain. Their research focuses on green building and urban thermal environment modeling, resulting in highly cited and influential outputs.

The collaboration network among authors in this domain is characterized by its complexity and stability, featuring multiple research teams led by core authors. Certain researchers act as bridges between distinct clusters, thereby facilitating international cooperation. This model of multi-center, cross-regional, and cross-disciplinary collaboration offers significant support for the ongoing development and innovation of UHI research, particularly in the context of GI mitigation.

3.4. Institutional Contributions

Institutional analysis plays a crucial role in elucidating the academic landscape and identifying key contributors within specific research domains [47]. By examining the scholarly impact and collaborative networks of institutions, researchers can gain valuable insights into prominent research entities, thereby informing future studies and fostering inter-institutional collaborations. In the context of GI for mitigating UHI,

Table 2. Top 10 institutions by number of publications.

Rank	Institutions	NP	NC	AC	Total Link Strength
1	Chinese Academy of Sciences	25	1062	42.28	88
2	University of New South Wales	19	1521	80.05	33
3	Arizona State University	17	1031	60.65	25
4	National University of Singapore	16	1371	85.69	31
5	Victoria University	12	414	34.50	27
6	University of Hong Kong	12	686	57.17	12
7	Columbia University	10	1017	101.70	25
8	Seoul National University	10	317	31.70	23
9	Texas A&M University	10	356	35.60	17
10	University of Natural Resources and Life Sciences	10	144	14.40	12

Note: NP = Number of Publications; NC = Number of Citations; AC = Average Citations per paper; Total Link Strength = The cumulative strength of all collaborative links between a given institution and others, as calculated by VOSviewer. It is computed as TLSᵢ = ∑ⱼ≠ᵢ Sᵢⱼ, where Sᵢⱼ denotes the strength of the link between institution i and institution j.

presents the top ten institutions ranked by publication volume, providing a clear representation of research distribution and the academic influence of these institutions.

The data indicate that the Chinese Academy of Sciences leads with 25 publications, reflecting its sustained investment in research and organizational strengths in this field. The University of New South Wales and Arizona State University follow with 19 and 17 publications, respectively, highlighting the active engagement and international influence of Australian and American research institutions in studies related to UHI mitigation. Notably, the University of New South Wales stands out with a citation count of 1521, underscoring its exceptional performance in producing high-impact research. Similarly, Arizona State University, with 1031 citations, and the National University of Singapore, with 1371 citations, demonstrate significant contributions, indicating that their research outputs have garnered widespread recognition and attention within the global academic community.

Overall, research on GI aimed at addressing UHI challenges demonstrates a multi-centric and collaborative development trend globally. Institutions from countries such as China, the United States, Australia, and Singapore exhibit strong research capabilities and international influence in this field, offering theoretical support and practical experience for global urban sustainable development initiatives.

To further explore inter-institutional collaborations, we generated a cooperation network map using VOSviewer (Figure 6). In this visualization, each node represents a research institution, with the size of each node proportional to the number of publications. The connections between nodes indicate collaborative relationships, while the thickness of the lines reflects the strength of these collaborations.

The overall structure of the network illustrates a densely connected, multi-centric collaboration pattern, indicative of a high density of academic cooperation and active international partnerships within this research domain. The Chinese Academy of Sciences occupies a central position in the network, characterized by the largest node size, signifying its prominent influence and leadership in collaborative research efforts. It maintains robust partnerships with domestic institutions such as Nanjing University, Tongji University, Tsinghua University, and East China Normal University, as well as with internationally renowned universities like the National University of Singapore and the University of New South Wales.

Additionally, some peripheral nodes, including South China University of Technology and the University of Perugia, while having a relatively smaller presence in the network, maintain collaborative ties with core institutions. This indicates their potential for enhanced research activity and development within the field.

In summary, the institutional collaboration network within this research domain demonstrates a ‘core-periphery’ structure, characterized by a multipolar collaboration framework centered around institutions in China, the Asia-Pacific region, and Europe. High-frequency interactions among core institutions are pivotal for advancing knowledge dissemination and fostering technological synergy in the study of GI and UHI effects. Future efforts should focus on enhancing collaborations between peripheral and central institutions to improve the overall connectivity and innovative capacity of the research network.

3.5. Most Influential Journals

In the field of GI for mitigating UHI effects, the selection of appropriate journals is crucial for the academic dissemination and impact of research findings.

Table 3. Top 10 journals by publication volume.

Rank	Journal	NP	NC	AC	H-Index	IF (JCR 2024)
1	Sustainability	90	1352	15.02	24	3.3
2	Building and Environment	74	4195	56.69	24	7.1
3	Urban Forestry & Urban Greening	54	2402	44.48	24	6.0
4	Sustainable Cities and Society	53	1778	33.55	17	11.7
5	Energy and Buildings	52	3235	62.21	16	6.6
6	Urban Climate	35	842	24.06	3.2	6.0
7	Science of the Total Environment	29	1824	62.90	4.9	8.2
8	Land	21	171	8.14	18	3.2
9	Landscape and Urban Planning	20	2256	112.80	16	7.9
10	Buildings	19	154	8.11	17	3.1

Note: NP = Number of Publications; NC = Number of Citations; AC = Average Citations per paper; H-index = Hirsch index; IF (JCR 2024) = Impact Factor (Journal Citation Reports 2024).

presents the top ten journals ranked by publication volume in this domain. As shown in Table 3, although the journal *Sustainability* leads with 90 publications, its average citation frequency per article is only 15.02, and its impact factor is 3.3, indicating that its overall academic visibility is relatively limited. In contrast, *Building and Environment* has slightly fewer publications (74) but boasts a higher average citation frequency per article (56.69) and a greater impact factor (7.1), suggesting that this journal exerts a stronger empirical influence and enjoys greater recognition in the field of building and thermal environment research. The journals *Science of the Total Environment* (IF = 8.2) and *Landscape and Urban Planning* (IF = 7.9) published 29 and 20 relevant articles, respectively, but their average citation frequencies were 62.90 and 112.80, with the latter being significantly higher. This discrepancy indicates that *Landscape and Urban Planning* has a more focused research theme and sustained citation impact at the intersection of urban planning and spatial policy, thereby providing its core articles with longer academic longevity.

Similarly, *Sustainable Cities and Society* (IF = 11.7) and *Urban Forestry & Urban Greening* (IF = 6.0) exhibit an opposite trend in average citation frequency per article (33.55 vs. 44.48). Despite having a higher impact factor, the broader scope of the former may dilute the academic visibility of individual articles. In contrast, the latter’s emphasis on urban greening and microclimate effects facilitates more concentrated citations.

In conclusion, relying solely on a single impact factor is inadequate for accurately assessing a journal’s true academic influence in this field. Conversely, the average citation frequency per article more effectively reflects a journal’s citation efficiency and academic activity on specific topics. This research demonstrates that journals with a clear thematic focus, rigorous research methods, and high alignment with policy or established issues, such as *Landscape and Urban Planning*, often garner higher academic responses despite having fewer publications. Therefore, researchers should consider not only quantitative metrics but also the journal’s thematic alignment, academic positioning, and potential impact when selecting journals for submission, in order to achieve efficient dissemination and sustained citation of their work.

3.6. Research Knowledge Base

Co-citation analysis serves as a pivotal method for unveiling the intellectual structure and thematic evolution within a research domain [48,49]. By examining the frequency with which pairs of documents are cited together, this approach identifies seminal works and core topics that have significantly influenced the field. In this study, CiteSpace software was employed to generate a co-citation network map (Figure 7), highlighting the most influential publications regarding the role of GI in mitigating UHI effects.

Among the highly cited works, Santamouris M’s 2014 article, “Cooling the Cities—A Review of Reflective and Green Roof Mitigation Technologies to Fight Heat Island and Improve Comfort in Urban Environments,” published in Solar Energy, stands out with 178 citations [50]. This comprehensive review systematically evaluates various rooftop technologies, including reflective and green roofs, in terms of their efficacy in reducing building surface temperatures, alleviating urban heat loads, and contributing to energy conservation. This study underscores the importance of integrating these technologies into urban planning and building policies to enhance urban thermal comfort and sustainability.

Another notable publication is the 2018 article by Besir AB et al. [51], titled “Green Roofs and Facades: A Comprehensive Review,” featured in Renewable and Sustainable Energy Reviews. With 157 citations, this work explores the technical performance, structural components, thermal properties, cooling mechanisms, maintenance challenges, and economic feasibility of green roofs and facades [51]. The authors emphasize the significant impact of factors such as plant species selection, substrate depth, and climatic conditions on the thermal performance and cooling efficiency of these systems. Additionally, the study highlights the potential of green facades for energy savings and urban aesthetic enhancement, providing valuable insights for integrated green building design. Collectively, these foundational studies have established a framework for subsequent research, offering critical theoretical perspectives and practical guidance for implementing GI in urban environments to mitigate UHI effects. Their high citation counts reflect their substantial influence and the ongoing relevance of their findings in advancing sustainable urban development strategies.

3.7. Keyword Analysis

3.7.1. Keyword Co-Occurrence Analysis

Keyword co-occurrence analysis serves as a pivotal method for uncovering research hotspots, thematic interrelations, and emerging trends within a specific field [52,53]. Utilizing VOSviewer, this study constructs a co-occurrence network and conducts a cluster analysis of high-frequency keywords pertinent to the role of GI in mitigating UHI effects. In the generated network visualization (Figure 8), each node represents a keyword, with the node size proportional to its frequency of occurrence. The thickness of the connecting lines indicates the strength of the association between keywords, while distinct colors denote different thematic clusters. Furthermore, to present the significance of keywords more intuitively, this study statistically analyzed the top 20 most frequently occurring keywords (see

Table 4. Ranking of keywords by number of occurrences.

Ranking	Keyword	Occurrences	Total Link Strength
1	urban heat island	279	2865
2	city	232	2392
3	urban heat-island	215	2289
4	green infrastructure	209	2059
5	impact	206	2237
6	mitigation	173	1825
7	temperature	173	1842
8	vegetation	149	1658
9	green roofs	148	1534
10	performance	141	1449
11	climate	135	1471
12	green roof	129	1233
13	microclimate	111	1249
14	heat-island	100	1075
15	thermal comfort	97	1023
16	model	93	942
17	climate-change	92	961
18	energy	89	961
19	benefits	83	825
20	ecosystem services	82	797

). The results indicate that “urban heat island” (279 occurrences) and “city” (232 occurrences) are the two most prevalent keywords, underscoring that UHI and its management are central topics within this field. The frequent appearance of keywords such as “GI,” “impact,” and “mitigation” further highlights the essential role of GI in improving urban thermal environments and evaluating their effects.

Cluster 1: Remote Sensing and Urban Thermal Environment Modeling

This cluster emphasizes technological approaches to monitoring and modeling urban thermal environments. Key terms include “land surface temperature,” “urban green infrastructure,” “urban thermal environment,” “remote sensing,” and “numerical simulation.” Studies in this domain employ spatial information technologies to quantify UHI intensity and assess the spatial distribution and effectiveness of various types of GI. Common methodologies involve extracting thermal indicators from remote sensing imagery and utilizing Geographic Information Systems (GISs) for visualizing urban heat patterns. Advancements in modeling techniques have led to the integration of machine learning algorithms, such as random forests, and physical simulation models like Energy Plus, thereby enhancing predictive accuracy and understanding of thermal dynamics. The incorporation of concepts such as “local climate zones” has further facilitated comparative analyses across different urban contexts, enabling multi-scale evaluations of the cooling effects of GI.

Cluster 2: Microclimate Regulation and Thermal Comfort

This cluster focuses on the interplay between GI and urban microclimates, incorporating keywords such as “UHI,” “thermal comfort,” “microclimate,” “outdoor thermal comfort,” “green wall,” and “cool roof.” Research within this domain investigates how elements of GI influence local climatic conditions and enhance outdoor thermal comfort. Strategies such as green walls, permeable pavements, and rooftop greening are analyzed for their adaptability across various climatic zones. Methodologies typically combine field measurements with microclimate simulations to assess cooling efficacy and human thermal perception, while also considering the role of urban morphology in modulating these effects.

Cluster 3: Urban Sustainability and Ecosystem Services

This cluster explores the broader implications of GI within urban sustainability frameworks. Key terms include “urban sustainability,” “urban greening,” “NBS,” “GI,” and “ecosystem services.” Research highlights the multifaceted benefits of GI, such as enhancing ecosystem services, promoting climate resilience, and fostering social equity. The interdisciplinary nature of this cluster reflects a convergence of ecological, social, and urban planning perspectives, underscoring the role of GI as a nexus between natural processes and urban governance.

Cluster 4: Urban Planning and Policy Integration

This cluster encompasses strategic and policy-oriented studies, featuring keywords such as “urban planning,” “climate change,” “mitigation,” “passive cooling,” and “sustainable development.” The research focuses on the integration of GI into urban planning and climate adaptation policies, exploring system-level design approaches and governance mechanisms. Methodologies employed include policy analysis, urban-scale simulations, and comparative case studies, which elucidate the relationship between the implementation of GI and low-carbon urban development.

Cluster 5: Green Roofs and Building-Level Interventions

Focusing on building-scale applications, this cluster emphasizes “green roof” as a core keyword, alongside “vegetation,” “thermal performance,” “stormwater management,” and “climate adaptation.” Research investigates the contributions of green roofs to thermal regulation, energy efficiency, and ecological functions. Analyses typically involve structural assessments, empirical measurements, and thermal simulations to elucidate how green roofs modulate heat flux, evapotranspiration, and energy balance. The multifunctionality of green roofs, which includes stormwater management and air purification, highlights their significance in developing integrated building-environment systems.

Research on the role of GI in mitigating UHI effects has evolved from initial temperature monitoring and thermal modeling to include aspects such as microclimate regulation, ecosystem services, urban governance, and policy integration. Future studies should focus on deepening the evaluation of the multifunctional synergies of GI and reinforcing its systemic role within urban sustainability strategies.

3.7.2. Temporal Evolution and Burst Analysis of Keywords

To comprehensively elucidate the developmental trajectory and emerging trends in research on GI for mitigating UHI effects, this study utilized CiteSpace to construct a temporal keyword co-occurrence map (Figure 9) and to identify the top 25 keywords exhibiting the strongest citation bursts over the past 25 years (Figure 10). In the Keyword Change Map, the horizontal axis represents the temporal span, while the vertical axis reflects keyword frequency and interrelations. The size of each node corresponds to the frequency of keyword occurrences, with color variations indicating periods of heightened activity. Connecting lines illustrate co-occurrence relationships. In the burst detection map, red lines signify the duration of a keyword’s burst period, while blue lines indicate the overall presence of the keyword. The “strength” metric quantifies the intensity of the burst, and the “begin” and “end” labels denote the onset and conclusion of each burst period.

Phase I (2003–2008): Foundational Mechanistic Studies

During this initial phase, research predominantly focused on the fundamental mechanisms underlying the UHI phenomenon. Key recurring terms included “UHI,” “energy,” “simulation,” “surface,” and “trees.” Studies primarily employed numerical simulations and empirical observations to investigate how urban morphology, building materials, and vegetation affect thermal dynamics. Techniques such as energy balance modeling and thermal imaging were utilized to analyze surface temperature distributions, thereby laying the groundwork for subsequent GI interventions. Preliminary explorations into the role of vegetation and green spaces in modulating urban microclimates also emerged; however, systematic evaluations of their efficacy were limited during this period [54,55].

Phase II (2009–2013): Emergence of GI Concepts

In this phase, the research focus shifted towards the conceptualization and implementation of GI as a strategy for mitigating UHI. Notably, the term “green roof” exhibited the highest burst strength (8.92) and maintained prominence from 2009 to 2016, underscoring its significance in early GI research. Concurrent keywords, such as “GI” and “climate change” gained traction, reflect a growing recognition of the multifaceted benefits of GI in addressing urban environmental challenges [56].

Phase III (2014–2017): Diversification of GI Applications

This period witnessed an expansion in the scope of GI research, with increased attention to diverse applications and performance metrics. Keywords such as “GI,” “green roofs,” “climate change,” “canopy model,” “solar reflectance,” “energy performance,” “urban greening,” and “living walls” became prevalent. Research efforts broadened to encompass the evaluation of GI’s ecological services, enhancements in energy efficiency, and aesthetic contributions. Methodologies evolved to include experimental testing, numerical modeling, and the development of multidimensional performance assessment frameworks [57,58,59]. The adaptive capacity of GI in mitigating urban thermal risks under climate change scenarios emerged as a focal point of inquiry [60].

Phase IV (2018–Present): Integration of Advanced Technologies and Socio-Ecological Considerations

In the most recent phase, research on GI has increasingly incorporated advanced technological tools and addressed broader socio-ecological issues. Emerging keywords such as “blue-green infrastructure,” “ANNs,” “environmental justice,” “NBS,” “evapotranspiration,” “green space,” and “urban microclimate” indicate a trend towards interdisciplinary approaches. The application of artificial intelligence and big data analytics has enhanced the precision of GI performance evaluations. Simultaneously, considerations of social equity, environmental ethics, and governance structures have become integral to the discourse surrounding GI. Since 2022, there has been a notable surge in research focusing on ecological functionalities and urban ecosystem services, signaling a paradigm shift in which GI is perceived not merely as a technological intervention but as a holistic pathway towards sustainable urban development [61].

4. Discussion

4.1. Key Research Findings

The evolution of research on GI for mitigating UHI effects has been characterized by diverse and dynamic developments [62]. Over time, the field has experienced significant shifts in research directions and focal points [63]. Emerging areas of study often extend or deepen existing topics, reflecting the field’s responsiveness to evolving challenges and insights. Despite numerous reviews and analyses, a comprehensive and systematic knowledge framework that encapsulates the multifaceted nature of GI in UHI mitigation is still lacking. This gap hinders researchers and practitioners from readily accessing and applying critical information. Consequently, there is a pressing need to establish an integrative and visually intuitive theoretical framework. Such a framework would not only delineate the current landscape of GI research in UHI mitigation but also guide future investigative and practical endeavors. Figure 11 presents a synthesized theoretical knowledge framework.

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The research on the role of GI in mitigating the UHI effect can be categorized into three distinct phases based on publication trends: Phase 1 (2000–2012) marks the initiation phase. Phase 2 (2013–2020) shows a steady increase in publications, rising from 13 in 2013 to 86 in 2020. Phase 3 (2021–2024) exhibits sustained high publication volumes, exceeding 100 annually, with peaks of 124 in 2021 and 140 in 2024.

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The selection of journals reflects the academic dissemination and impact of research findings [64,65]. The top three journals with the highest publication frequencies are *Sustainability*, *Building and Environment*, and *Urban Forestry & Urban Greening*. The most influential journals in this field include *Building and Environment*, *Science of the Total Environment*, and *Landscape and Urban Planning*. Notable co-cited journals include *Solar Energy* and *Renewable and Sustainable Energy Reviews*, with key co-cited papers authored by Santamouris M. (2014) and Besir AB (2018).

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Analyzing collaborative networks helps identify key researchers, teams, and institutions, thereby illuminating pathways of knowledge dissemination [66,67]. In terms of regional collaboration, China leads, with 233 publications, followed by the United States with 164 and Italy with 115. Regarding author collaboration, Santamouris Mattheos is the most prolific author with 13 papers, followed by Jim CY and Pisello Anna Laura, who have authored 11 and 8 papers, respectively. Institutional collaboration is led by the Chinese Academy of Sciences, which has 25 publications, followed by the University of New South Wales with 19, and Arizona State University with 17.

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Keyword co-occurrence analysis reveals research hotspots, thematic relationships, and trends [68,69]. The most frequent keywords identified are “UHI,” “green roof,” and “GI.” Emerging hotspot keywords include “blue-green infrastructure,” “ ANNs,” and “NBS,” representing the latest trends in the field. Burst keywords such as “NBS,” “evapotranspiration,” and “green space” have exhibited significant burst activity, indicating their increasing prominence in recent research. These findings provide valuable guidance for future scholars in the field.

Current research focuses on five key thematic clusters: Remote sensing-driven thermal environment modeling, which emphasizes land surface temperature, remote sensing, and random forests. This area of study highlights surface temperature inversion and machine learning predictions to elucidate the thermal patterns of the urban subsurface. In a Berlin case study, circuit theory was applied to optimize cold island corridors, enhancing green space connectivity by 28% [70]. Microclimate control technologies, focusing on vertical greening, cool roofs, and outdoor thermal comfort, highlight the impact of engineering interventions on local thermal conditions [71,72]. Social ecosystem services, characterized by a strong co-occurrence of NBS and environmental justice, demonstrate the multifunctional synergy and quantification of equity in green spaces [73]. Climate-adaptive planning, which establishes a triangular linkage among urban planning, climate change, and mitigation, promotes policy integration. Lastly, the optimization of green roof technology, incorporating evapotranspiration, thermal performance, and stormwater management, elucidates the core mechanisms of evaporative cooling and its synergy with stormwater management [74,75].

In mitigating UHI, the application of GI has significantly reduced the risk of elevated temperatures in cities [76]. In densely populated urban neighborhoods, increasing tree canopy cover and optimizing the design of green spaces can substantially lower both land surface temperatures (LSTs) and human thermal discomfort [77,78]. For instance, during the renovation of Xicheng Hao Street in Wuchang District, Wuhan—a previously dilapidated residential area—the initial high-temperature risk rate was 67.8%. By introducing additional trees within the limited space, canopy coverage increased to 27.26%. Consequently, the high-risk heat zone was reduced by 45.3%, resulting in an overall decline in the risk rate to 37.07% [79].

In recent years, there has been growing attention to the intersection of ANNs and environmental justice. While ANN technologies have significantly enhanced the efficiency of environmental data analysis and decision-making, disparities in resource allocation and service coverage persist [80,81]. A notable example is Seattle, where the city prioritized deploying dense ANN-based environmental monitoring networks in low-income neighborhoods and communities with high proportions of ethnic minorities. This strategy ensured equitable access to pollution alerts and green space planning services. By integrating algorithmic optimization with social equity objectives, this approach provides a valuable model for addressing environmental injustice through emerging technologies [82,83].

4.2. Research Hotspots and Trend Analysis

An analysis of recently emerging high-frequency keywords reveals that topics such as urban GI, NBS, urban microclimate, environmental justice, carbon sequestration, remote sensing, and machine learning are becoming prominent frontiers in the field. The introduction of these concepts marks a new phase in understanding the role of GI in mitigating UHI. GI is no longer viewed solely as a physical cooling tool; instead, it is increasingly recognized as a multidimensional solution that integrates ecological regulation, social equity, and intelligent management. Within this framework, GI serves as a central mechanism for building resilient, sustainable, and equitable cities.

A deeper examination reveals the fundamental mechanism by which GI mitigates UHI effects: its capacity to effectively regulate urban microclimates [84,85]. For instance, vertical gardens in Singapore have been shown to reduce building surface temperatures by from 8 to 12 °C [86,87]. Similarly, research conducted in Berlin’s Tiergarten Park demonstrates that mixed oak–beech forests can lower LST by from 2.3 to 4.1 °C during peak summer heat within a one-kilometer radius, with canopy shading accounting for 62% of the cooling effect. Urban forests, as integrated systems of tree-dominated green spaces, embody a multi-layered set of cooling mechanisms [88,89,90]. As illustrated in Figure 12, these mechanisms include canopy shading that reduces radiation, evapotranspiration-driven heat dissipation, synergistic cooling effects with sponge city infrastructures and water bodies, and localized circulation regulation [91,92,93]. Collectively, these processes contribute to lowering urban surface temperatures. Future research should focus on quantifying the long-term cooling performance of various types of GI. Additionally, it is essential to develop configuration models tailored to diverse climate zones to optimize spatial layouts and maximize cooling benefits [94].

Beyond their cooling function, GI also serves as a critical urban carbon sink, with its carbon sequestration potential receiving increasing attention under the carbon neutrality agenda [95,96,97]. For example, urban forests in Chicago sequester approximately 250,000 tons of carbon annually, equivalent to offsetting the emissions of 60,000 cars [98]. Similarly, green roofs in London contribute to urban cooling and provide an annual carbon sink of 0.35 kg per square meter [99]. However, the lack of standardized carbon accounting methods and the limited application of life cycle assessments remain significant challenges [100,101,102]. Advancing the development of GI-based carbon trading mechanisms, designing planning strategies that integrate the dual goals of cooling and carbon sequestration, and quantifying the emission reductions achieved by replacing conventional gray infrastructure represent important directions for future research [103].

In terms of public health and environmental justice, GI is widely recognized for its role in improving residents’ health by reducing heat exposure and promoting physical activity [104,105,106]. However, concerns regarding the equity of spatial distribution are becoming increasingly prominent. In New York City, for example, green space coverage in low-income neighborhoods is 37% lower than in affluent areas, contributing to a 2.3-fold higher incidence of heat-related illnesses [107]. Initiatives such as Medellín’s Green Corridor Project in Colombia and community garden programs in Shenzhen demonstrate that using heat risk maps to guide GI allocation is an effective approach to improving health equity [108,109]. Future research should place greater emphasis on assessing the health benefits of GI for vulnerable populations and on establishing dynamic models that link heat stress to health outcomes [110].

With the increasing frequency of extreme climate events, the traditional gray infrastructure’s single-function disaster prevention model faces significant challenges [111]. A leading trend is the evolution of GI towards a resilience governance system characterized by technological integration, intelligent coordination, and institutional innovation [112,113]. For instance, New York City has pioneered the integration of green roofs with distributed energy storage systems [114,115]. By utilizing smart controllers to pre-drain reservoirs before heavy rainfall, the city achieved an 83% reduction in runoff and a peak cooling effect of 4.2 °C, demonstrating the multifunctional benefits of flood retention, thermal regulation, and energy storage. Similarly, Rotterdam’s “Water Square” combines rain gardens with public recreational facilities. Its adjustable water storage modules improved flood protection standards from a once-in-30-year event to a once-in-100-year event, setting a benchmark for the multifunctional use of urban space. Future research should focus on developing integrated optimization models that align cooling, carbon sequestration, and health objectives, thereby fostering interdisciplinary knowledge production and advancing the integration of ecological intelligence with social governance innovation [116,117].

Addressing the challenge of increasingly heterogeneous heat exposure requires a paradigm of precision regulation supported by intelligent monitoring technologies [118,119]. Traditional experience-based GI planning often fails to ensure equitable resource allocation, making it essential to develop an integrated system that encompasses data sensing, model simulation, and policy response [120]. In Shanghai, the ‘Green Intelligence Cloud’ platform combines satellite remote sensing, drone-based thermal imaging, and IoT canopy sensors, enabling the first minute-scale dynamic diagnosis of GI cooling performance at the city level [121,122]. In Seoul, convolutional neural networks were employed to integrate a decade of thermal maps with population vulnerability data, resulting in street-level GI optimization schemes that increased the prioritization of cooling facilities for disadvantaged communities by 35% [123]. In London, real-time heat maps have been directly incorporated into urban planning approval systems, mandating that new developments include GI-based cooling facilities [124]. Strengthening collaboration among humans, machines, and the environment; exploring the integration of thermodynamic mechanisms with governance technologies such as blockchain; and monetizing cooling performance while advancing heat equity and green space accessibility are critical directions for future research driven by intelligent monitoring [125,126].

4.3. Implications for Urban Planning

Although existing GI demonstrates significant potential in mitigating the UHI effect, its widespread implementation faces notable limitations and challenges. First, the spatial distribution of green spaces often exhibits an “island-like” pattern, with insufficient connectivity between blue-green areas. This fragmentation reduces cooling efficiency by more than 30%. Additionally, high-density built-up zones typically lack adequate green coverage, while the limited load-bearing capacity of older buildings constrains the promotion of vertical greening. Second, artificial intelligence (AI) models lack access to high-resolution urban morphology data, resulting in prediction errors that can exceed 15%. Moreover, cross-scale models remain disconnected, and block-level thermal interventions are not effectively integrated with city-level planning. Third, approximately 78% of cities lack specialized GI regulations. Carbon trading mechanisms and green coverage requirements are not embedded within land-transfer policies. Institutional responsibilities are fragmented, and mechanisms for public participation remain weak. To address these challenges, systematic planning strategies are essential:

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Spatial Network Reconstruction: Leveraging Shanghai’s adaptive cooling network framework, circuit theory models can identify critical cooling sources and ecological corridors, thereby optimizing the “source–corridor–node” topology. This strategy involves densifying small-scale green spaces, expanding vertical greening, reserving 20% of land for blue–green infrastructure, and aligning development with urban ventilation corridors.

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Integration of Multi-Source Technologies: Data from the GHRS project—including thermal remote sensing, population mobility, and building energy consumption—can be integrated to establish a “monitoring–simulation–early warning” decision-making framework. The application of the XGBoost algorithm can optimize greening configurations, while coupling with the WRF-UCM model enables simulation of ventilation corridor impacts.

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Full-Cycle Policy Coordination: Policies should establish ecological coverage baselines for “zero-carbon parks,” incorporate evapotranspiration efficiency into green building certifications, and promote “carbon trading + floor area ratio (FAR) incentives.” A dedicated UHI effects mitigation task force should be established to integrate the functions of the landscape, transportation, and energy departments. Concurrently, a “community–expert” co-governance platform should be developed to encourage public participation in the design process.

5. Conclusions

This study employs bibliometric methods to systematically analyze global research trends on the application of GI for mitigating UHI effects from 2000 to 2025. From 2000 to 2012 (initiation period), the average annual publication volume was fewer than 10, with research primarily focusing on UHI mechanisms and empirical investigations of individual technologies. Annual publications then increased to 86, and research themes expanded to include microclimate modeling and ecosystem service assessments. Annual publications then exceeded 100, reaching 140 in 2024. This was led by China (233 publications), the United States (164), and EU countries (Italy 115); participation from regions such as Africa and Latin America remains limited, underscoring the need for systematic capacity-building and policy interventions to bridge these gaps.

Early studies primarily focused on topics such as energy consumption, solar reflectance, canopy models, and climate change. Recent research has shifted toward emerging areas, including blue–green infrastructure, ANNs, environmental justice, NB, and urban microclimates. Interregional, interdisciplinary, and North–South collaborations remain significantly imbalanced, limiting the large-scale dissemination of GI knowledge and its global implementation. Co-citation analysis highlights the significant contributions of scholars such as Santamouris, M., and Besir, A.B., in advancing the understanding of GI for UHI mitigation.

Based on the aforementioned research findings, this paper proposes several theoretical and practical recommendations. Deepening the ‘cooling-carbon sequestration-health’ coupling mechanism model, integrating remote sensing, the Internet of Things (IoT), and machine learning technologies to create a city-level dynamic monitoring platform. Establishing a three-in-one governance theory encompassing spatial planning, policy incentives, and public participation, creating a community co-governance platform to optimize the renovation of aging urban areas. Improving the assessment model for heat exposure risk and health equity, prioritizing coverage for vulnerable communities, and integrating these considerations into smart monitoring networks. Exploring the collaborative innovation theory of ‘high-precision models and localized knowledge,’ building a north–south demonstration city pairing platform, and facilitating the two-way flow of technology from developed countries alongside low-cost experiences from developing countries.

6. Limitations

In this study, we employ bibliometric methods and utilize VOSviewer, CiteSpace, and Scimago Graphica to conduct a visual analysis of the application of GI in mitigating UHI from 2000 to 2025. We summarize the current state of research and forecast future trends. However, several limitations must be acknowledged. This study relies exclusively on the Web of Science database as its data source, which may lead to the exclusion of relevant literature. High-quality research conducted in developing countries is often published in local journals that are not indexed by WoS. Furthermore, valuable and underrecognized gray literature may also be omitted. In future research, we plan to incorporate a broader range of databases, including Scopus, PubMed, CNKI, and SciELO. This will help capture research outputs from non-English-speaking countries and emerging fields, thereby enhancing the representativeness of our findings. Additionally, to mitigate single-source bias and account for variations across databases, we will explore integrating citation data using statistical methods such as the arithmetic mean, geometric mean, or harmonic mean.