Analysis of Knowledge Graph: Hotspots and Future Trends in Environmental Education Research

To explore potential commonalities in environmental education research hotspots, the Logarithmic Likelihood Ratio (LLR) algorithm (Kao et al., 2022) [10] was applied to cluster keywords based on their similarity. Additionally, a change-point detection algorithm (Li et al., 2023) [19] was employed to identify keyword pairs exhibiting significant new trends or rapid changes within specific time ranges. This methodology led to the identification of 15 clusters of varying sizes, as illustrated in Figure 5.

The modularity cluster network value in Figure 5 was 0.4979 (>0.3), signifying a significant cluster structure (Shen et al., 2023) [20]. The Silhouette parameter, assessing keyword similarities within a cluster and ranging from −1 to 1, yielded an average value of 0.8178, surpassing 0.7, indicating convincing clustering results (Li et al., 2023) [19].

The CiteSpace-generated clustering labels, along with other core keywords within each cluster, facilitated further exploration of related literature. Manual induction was employed to summarize the research topics of each cluster (Table 3), leading to the categorization of environmental education research into five main themes: environmental awareness and literacy, theories in environmental education, delivery modes and methods, developments and implementation of environmental education, and the intersection of climate change and environmental justice.

The first theme, ‘environmental awareness and literacy’, focused on relationships between environmental knowledge, attitudes, and behaviors. Keywords included literacy, environmental behavior, environmental protection, and environmental concerns. Environmental literacy was explored as encompassing awareness, sensitivity, understanding of solutions, values, motivations, skills, and abilities related to environmental protection, and a willingness to take environmental improvement actions (Roth, 1992) [21]. Studies, such as Chu et al. (2007) [22] and Činčera, Kroufek, and Bogner (2022) [23], revealed factors influencing environmental literacy, including gender, environmental information sources, parents’ educational backgrounds, and correlations between environmental attitudes and behaviors.

Vare (2020) [24] contributed to this cluster by adopting a cultural-historical activity theoretical perspective, conceptualizing schools as activity systems for implementing environmental education. Through interviews with teachers and principals from 12 schools in England, the study identified 15 contradictions that could arise during the implementation of environmentally sustainable development education within schools. These contradictions were categorized into four levels: within an activity system element, between different activity elements, between the object of the dominant activity form and the object of more advanced cultural forms, and between the central activity and neighboring activities. The study also explored teachers’ approaches to resolving these contradictions, highlighting instances where teachers may have higher expectations for school-based environmental education than the school leadership, resulting in frustration and a sense of powerlessness. Identifying these contradictions can empower teachers to provide students with meaningful and contextualized environmental education learning opportunities, fostering highly adaptable, resilient learners and improving teachers’ self-esteem.

The third thematic category delved into delivery modes and methods of environmental education, encompassing keywords such as place-based education, land education, indigenous education, and participatory action research. This category explored novel teaching modes and methods in environmental education. For instance, Albareda-Tiana et al. (2018, 2019) [25,26] proposed three sustainable development education strategies: problem-based learning (PBL), project-oriented learning (POL), and interdisciplinary seminars. Through experiments on pre-service teacher training students, the study found that project-oriented learning (POL) was particularly effective in cultivating sustainability thinking in higher education.

Moreover, localized education models were also examined within environmental education. Localized education, rooted in the local or community environment, links education and student learning to local environmental development requirements. It fosters interdisciplinary learning processes grounded in the local natural world, facilitating multifaceted learning (Vinlove, 2015) [27]. Ladachar, PooThawee, and Ladachart (2020) [28] investigated the understanding of smog-related issues among Thai students of various ages, using open questionnaires and semi-structured interviews to gather data for the development of localized smog education courses. Similarly, Herman, Zeidler, and Newton (2020) [29] conducted a qualitative study on college students in Yellowstone, after they received localized teaching on environmental and social science issues, revealing shifts in attitudes towards human and natural welfare.

The fourth category focused on developments and implementation of environmental education. From one perspective, it explored the role of environmental education and key issues for groups receiving it. Pauw et al. (2015) [30] found that sustainable development education in Sweden increased students’ awareness of sustainable development. Glavič (2020) [31] identified twelve key issues in sustainable development education from environmental, societal, and economic perspectives. Another perspective focused on the implementation of environmental education, particularly sustainable development education. For instance, Waltner et al. (2020) [32] investigated its implementation in German middle schools, revealing an increase in teachers’ understanding of and views on sustainable development goals between 2007 and 2019. The study suggested frequent evaluation of teachers’ knowledge and attitudes, increased teacher support through training, and further integration of sustainable development education with other teaching course structures.

The fifth category centered on the intersection of climate change and environmental justice. Studies have recommended that sustainable development education should encompass diverse disciplines, addressing issues like climate change and poverty reduction. For a comprehensive understanding of the past, present, and future impacts at local, regional, and global levels, sustainable development education must integrate aspects of the environment, society, the economy, their interrelationships, and temporal and spatial interactions. Given the conflicts of interest between individual, economic, social, and environmental goals, holistic sustainable development perspectives emphasize the importance of social and cultural factors in causing environmental problems. Education, transcending disciplines, should encompass both local and global perspectives and consider past, present, and future generations (Borg et al., 2014) [33].

Environmental education, grounded in the present and potential future impacts, should address conflicts of interest between individual, economic, social, and environmental goals. Valdez et al. (2017) [34] found that attention to climate change and discussions with family and friends about climate change could predict individual climate change behaviors. Students from cities with high socioeconomic status exhibited a higher likelihood of engaging in climate change behaviors compared to students from low socioeconomic status cities or rural schools. Therefore, giving more attention to climate change news and incorporating these discussions into environmental education could foster more positive behaviors toward climate change solutions and better address conflicts of interest.

Climate change is also incorporated into K-12 education in Western settings. Siegne and Stapert (2020) [35] studied a middle-school climate change course integrated into the comprehensive social studies and language arts framework, developed collaboratively by a private school, a non-profit climate education institution, and a government agency (NOAA). A year after the course implementation, students who had participated in the course showed significant improvements in climate literacy and overall engagement in climate-change-related activities. This underscores the effectiveness of interdisciplinary environmental education research, particularly in social-science-based climate change education.

The CiteSpace Timeview function facilitates the analysis of keywords over different periods, revealing the evolutionary research paths. This allows researchers to intuitively comprehend keyword distribution characteristics at various times and identify future research trends (Tao and Lin, 2023) [36]. Thus, CiteSpace Timeview was employed to analyze environmental education research keywords spanning 2013–2022, resulting in the development of a keywords timeline map (Figure 6). This keywords timeline map organizes keywords in chronological order, with circle nodes reflecting the frequency of corresponding keywords. The size of each node represents the magnitude of the keyword’s occurrence within the dataset (Tao and Tao, 2024) [15]. Combining this analysis with high-frequency keywords from each stage, the evolution of research hotspots was observed to unfold in four stages.

The first stage (before 2013) primarily focused on cultivating environmental awareness and values. Figure 6 illustrates that international environmental education research was relatively mature before 2013. High-frequency vocabulary in this stage included education for sustainable development, environmental knowledge, environmental awareness, environmental concern, and teacher training. The primary focuses were: (1) environmental awareness—enhancing individual awareness and sensitivity to environmental issues; (2) environmental knowledge—disseminating nature and ecological protection knowledge, transforming fragmentary individual knowledge into a systematic knowledge system, and cultivating a correct understanding of the relationship between humans and nature; (3) pro-environmental attitude—establishing environmental values and fostering subjective initiatives to engage in pro-environmental behaviors; and (4) pro-environmental skills—cultivating individual environmental protection skills and enhancing individual abilities to address environmental problems.

Simultaneously, local characteristics, including histories, culture, social politics, economics, and the natural environment, were integrated into the teaching process to enhance students’ sense of belonging and improve their environmental responsibility. Educational strategies in this stage emphasized the active use of local materials and resources, expanded the educational space, encouraged in-depth exploration of local events and phenomena, and promoted meaningful learning experiences through simulated or direct participation. For instance, Thomas, Teel, and Bruyere (2014) [37] found that localized cultural, social, and environmental education delivered to 12 students from Hawaiian rural communities enhanced their knowledge of nature, increased their knowledge, and deepened their understanding of their local environment.

In the second stage (2014 to 2018), the second main focus in environmental education research was interdisciplinary integration. Recognizing that social, economic, and environmental complexities cannot be resolved by a single academic discipline, there was a growing emphasis on integrating natural science, humanities, and social sciences to effectively address environmental challenges. Environmental teaching and learning required the fusion of these various disciplines to ensure comprehensive and impactful education. Scholars argued that environmental educators should possess knowledge in behavioral psychology, pedagogy, marketing, and sociology principles (Ardoin, Bowers, and Gaillard, 2020) [4]. For instance, Silbernagel et al. (2015) [38] developed a comprehensive, localized, classroom-based science education project integrating environmental humanities, technology, and aquatic science under a spatial background to enhance students’ knowledge about estuary environments and culture.

The third stage (2019 to 2022) shifted focus to the integration of environmental education systems and new ideological trends. High-frequency vocabulary during this period included climate change education, transformative learning, citizen science, education for environmental citizenship, secondary education, emotion, ethics, and green. Two primary research directions emerged. (1) Shaping and cultivating environmental experiences, natural understanding, treatment methods, and ideology through systematic integration. This approach aimed to enable people to better address environmental problems by holistically incorporating social, political, and economic content into environmental education. Research attention increased towards environmental citizenship education, which raises public awareness of environmental problems from lifestyle, cultural, and systemic perspectives, promoting sustainable environmental development. Telešienė et al. (2021) [39] evaluated an educational intervention cultivating college student awareness of environmental citizenship, revealing positive changes. (2) Integrating social thought into environmental education to address global environmental governance challenges. Factors such as diplomacy, geopolitics, economic development, and system reform were recognized as intertwined with environmental issues. Environmental education systems incorporated new social developments in public science and the green economy to promote innovation and progress. Future directions involve exploring changes to traditional education methods, incorporating sociological, economic, and legal perspectives, and fostering dialogue between different disciplines. The focus will be on coordinating and balancing classroom environmental education with pro-environmental social and situational activities, cultivating sustainable development concepts, enhancing the sense of social responsibility and environmental literacy, developing pro-environment emotions, and motivating environmentally friendly behaviors. The experiential learning theory of environmental education proves its feasibility (Jose et al., 2017) [40]. Diverse environmental education paths are expected to develop, emphasizing macro contexts such as production globalization, the community of a shared future for mankind, and harmonious coexistence between people and nature.

To further observe the variations in a certain keyword across different years, this study employs the burst detection feature of CiteSpace to conduct a burst word detection on all keywords in the literature, yielding 30 words from 2013 to 2022 with the most significant burst, as shown in Table 4. “Strength” reflects the intensity of its burst and the “Begin” and “End” years indicate the span of its academic focus (Tao and Tao, 2024) [15]. The burst detection feature is capable of identifying keywords that have undergone significant changes in a short period, and it visually represents the trends of these abrupt changes in keywords across different time intervals through varying shades of color. This method illustrates the changing characteristics of research hotspots and potential research turning points in certain years, indirectly supporting the keywords timeline map. The burstiness level of an emergent word reflects its value at the forefront of the field; a higher burstiness rate indicates a greater contribution to the forefront of the domain. The end year of emergence shows the latest progress in a research area.

Table 4 reveals that the burst onset points for keywords began in 2013, with varying changes in burst intensity for different keywords. In terms of burst strength, “community” exhibits the highest intensity at 5.18, indicating it as a widely focused research frontier in the field of environmental education research. Regarding the timing of bursts, “informal education” appeared earliest, bursting in 2013 but fading from the field after three years. The burst start years for “community”, “education for sustainability”, and “conservation” were all in 2014, yet “conservation” had the longest burst duration, lasting five years. Keywords like “community”, “politics”, “context”, “environmental ethics”, “teacher training”, “climate change education”, and “green” all had burst durations of four years, reflecting prolonged scholarly attention in these research directions within the field of environmental education research.