Climate change is recognized as one of the most significant challenges of the 21st century, exerting a profound impact on natural systems, the economy, and social development (IPCC, 2023). While its effects are global, they also exhibit regional specificity, disproportionately affecting vulnerable communities, various economic sectors, and educational systems in distinct ways. Within this context, education is viewed not only as a means of imparting knowledge but also as a strategic tool for enhancing the capacity to adapt to and mitigate the effects of climate change. The concept of climate education has evolved over the years from a traditional understanding of environmental education to a broader, interdisciplinary approach that encompasses cognitive, social, and emotional dimensions. According to UNESCO reports (UNESCO, 2017; UNESCO, 2020), less than half of the world’s curricula systematically include climate-related topics, which are often limited to the natural sciences. This leads to gaps in the development of key competencies for sustainability, including critical thinking, active citizenship, and decision-making skills in conditions of uncertainty. In the European context, climate education is a priority in strategic documents such as the European Green Deal and the Education for Climate Coalition. These policies highlight the crucial role of educational institutions in promoting sustainable practices (European Green Deal, 2019; The Education for Climate Coalition, 2022) and in developing the necessary skills for the green transition. In recent years, theoretical and political debates have highlighted the need for a systematic approach to climate education that goes beyond individual knowledge and integrates competencies, institutional policies, and the assessment of education systems’ readiness (OECD, 2024a, 2024b). Current frameworks for climate education emphasize the need for an integrated, systemic approach that includes curriculum greening, assessment, resources, and institutional support (UNESCO, 2024). In this context, the fields are moving towards a broader understanding of climate literacy that goes beyond scientific knowledge and includes skills, motivation, and critical thinking (Boyd et al., 2025).

The latest international frameworks emphasize that climate education should be viewed as a systemic transformation of curriculum content and the school environment, rather than as isolated topics in individual subjects. In this context, UNESCO has established guidelines for ‘greening’ curricula by defining expected learning outcomes for different age groups and incorporating climate action into teaching and learning. Concurrently, the OECD underscores the importance of making education locally relevant (place-based) and of effectively bridging the divide between centralized objectives and the specific contexts of students and communities (UNESCO, 2024).

However, the application of these frameworks in a national context remains fragmented. In this regard, education systems in Eastern Europe lag significantly behind in integrating climate issues. In countries such as Bulgaria, the topic is mainly covered in geography and extracurricular activities. At the national level, Bulgaria still lacks a systematic framework for climate education. Some elements are integrated into geography, biology, and chemistry curricula; however, there is no interdisciplinary approach that links the natural and social sciences. This contradicts the European Commission’s requirements for creating „green skills “and preparing the workforce for the new challenges of the labor market (European Commission, 2022). At the same time, analyses by non-governmental organizations show that teachers often feel unprepared to teach on the subject due to a lack of specialized training and access to resources (Foss and Ko, 2019). The findings are used purely for literary and social context; this study does not measure psychological effects or classroom outcomes but rather evaluates the systemic readiness of education systems through policies, documents, and expert assessments.

Climate education cannot be viewed in isolation from socio-psychological dimensions. Research shows that young people experience growing climate anxiety, which affects their well-being and sense of the future. Education can play a key role in transforming this anxiety into constructive engagement and a sense of empowerment. Similar results are confirmed by an international survey of 10,000 young people, which found that 59% experience severe anxiety about their future in relation to climate change (Hickman et al., 2021). This highlights the dual commitment of climate education—to provide knowledge and skills, while also supporting emotional resilience. Theoretical frameworks demonstrate how education can influence values and attitudes through critical reflection, thereby integrating into the broader context of the relationship between society and nature, and addressing both individual and systemic levels of influence. Despite extensive literature on the subject, several studies highlight the lack of a universally accepted model for climate education. There are many effective strategies—from project-based learning to community participation—but their applicability depends on the local context. Students often have incomplete or incorrect ideas about climate processes, which necessitate scientifically sound teaching. Some authors (Lusambili et al., 2025; Trott, 2020) emphasize the importance of involving young people in community initiatives that connect school with real life. The lack of systematic analysis for Southeast Europe is particularly striking. While climate education in Scandinavian countries is integrated into strategic frameworks and supported by policies, in Bulgaria and neighboring countries, it remains underrepresented and largely project-oriented. This represents a significant research gap that hinders the adaptation of international best practices to the region’s specific needs. On this basis, the study aims to develop and apply an integrated index of educational systems’ readiness for climate education (CERI) to enable systematic assessment and international comparison. The primary objective is to identify strengths and gaps in policies, curricula, teacher training, resource provision, and school practices across five Southeast European countries: Bulgaria, Romania, Serbia, Greece, and Croatia. In line with this objective, the study poses the following research questions: 1. What are the key dimensions of systemic readiness for climate education, and how can they be measured? 2. To what extent do the five countries analyzed demonstrate institutional, resource, and pedagogical readiness to integrate climate change into education? 3. What factors explain the differences between countries, and which policies prove to be most effective? 4. What are the possibilities for applying the developed index (CERI) in a broader international context, and what practical recommendations can be formulated for education policy? In this way, the article combines theoretical contribution—through the creation of a new analytical tool—and practical value—through the identification of specific guidelines for improving climate education in the region and beyond.

Climate education is a comprehensive process designed to cultivate the knowledge, skills, attitudes, and values required to understand and address climate change, thereby enhancing both individual and collective capacity for action (Monroe et al., 2019). While it shares connections with environmental education, climate education is characterized by its interdisciplinary approach, emphasizing the social, economic, and political aspects of the climate crisis (Andersson and Öhman, 2016; Stevenson et al., 2013). The evolution of climate education has unfolded through several key stages: it began with “environmental education” in the 1970s (González-Gaudiano, 2006), progressed to “education for sustainable development” in the 1990s, and has now culminated in the contemporary understanding of “climate literacy” (Wals, 2015). This modern concept encompasses not only scientific knowledge but also decision-making skills, critical thinking, and active participation in public life (Leal Filho, 2020). Boyd et al. (2025) state that climate education is transitioning from a focus on scientific knowledge to a more comprehensive, systemic understanding of climate literacy. This includes enhancing skills, contextual understanding, and social learning.

Some authors emphasize that climate adaptation requires „a change in thinking patterns“—learning that enables individuals to rethink values, behaviors, and norms. The application of this type of learning shows that students adopt new action models (Mezirow, 1997). In the 2024–2025 period, the field of climate education literature is evolving in two significant ways. First, there is an increasing focus on the systematic ‘greening’ of curricula and the establishment of measurable learning outcomes. This approach views the quality of climate education as a combination of content, pedagogy, resources, and school practices.

Second, the significance of climate literacy and assessment is gaining traction, prompting inquiries into how educational systems can effectively measure knowledge, attitudes, and behavioral intentions without oversimplifying the subject’s complexity (OECD, 2024a, 2024b).

Simultaneously, numerous systematic studies are investigating teacher training and professional development as crucial components for effectively incorporating climate and sustainability education into schools. Additionally, practical frameworks for cross-curricular climate literacy are becoming increasingly significant, providing structured models for integrating these concepts across subjects and grade levels. This approach supports the meaningful integration of climate education within the curriculum (Aguilar et al., 2025). Vidal and Kuckuck (2025) systematically analyzes research on teachers’ competencies in sustainable development. The analysis highlights that, up until May 2024, most publications primarily emphasize knowledge and motivation. In contrast, action competence is less represented, which is crucial for understanding the gaps in current competency models.

At the same time, education contributes to building social resilience by improving “adaptive management literacy.” Thus, education systems are seen as intermediaries between scientific knowledge, public perception, and policy decisions (Folke et al., 2005).

Several studies show that the level of education of the population reflects the adaptive capacity of communities (Lutz et al., 2014). Higher climate literacy increases the likelihood that households will take preventive measures (Muttarak and Lutz, 2014).

In this context, individuals learn through imitation, interaction, and sharing, thus turning schools into centers of collective learning (Bandura, 2001).

The existing theoretical frameworks for transformative learning and socio-ecological systems enhance our understanding of the significance of climate education (Behzadian et al., 2012). The first theory posits that learning can facilitate changes in attitudes and behaviors through critical reflection. The second framework elucidates the interconnectedness of education, society, and natural systems, positioning education as a key component in promoting sustainability. In countries like Finland and Sweden, climate education is seamlessly integrated into the curriculum from primary school onward. Conversely, in many other nations, including those in Southeast Europe, such education remains inconsistent and is primarily confined to subjects such as geography and biology. Some authors (Reid, 2019; Shepardson et al., 2011) demonstrate that the absence of structured teaching in school subjects contributes to misconceptions about the greenhouse effect and global warming. This serves as a notable example of how inconsistent instruction on climate change in schools can lead to misunderstanding or a lack of clarity regarding its nature and potential solutions. Martin et al. (2025) show that existing tools for assessing climate literacy often focus solely on knowledge, which makes it difficult to assess broader competencies such as systems thinking and behavioral attitudes. Aeschbach et al. (2025), in a meta-analysis of climate education interventions, show that the effects on behavior and attitudes depend heavily on the availability of systems for monitoring and evaluating results, and not only on the content of the curricula.

In this context, several scholars (Meira Cartea, 2020) identify effective strategies, such as project-based learning, climate negotiation simulations, and role-playing games, to engage students and direct their attention to this critical issue. Even teachers with a basic understanding often struggle to gain the confidence to teach these concepts effectively (Andersson and Öhman, 2016). Institutional constraints, including the absence of national policies, resource shortages, and a lack of teacher incentives, pose significant barriers to effective climate education. Furthermore, climate education often remains outside the scope of formal professional development programs (Mochizuki and Bryan, 2015). Moreover, specialized training programs can significantly enhance teachers’ skills, especially when they integrate practical methods. In this context, it is essential to highlight that modern pedagogical innovations offer new opportunities for teaching and learning. Gamification and digital platforms enhance student engagement, demonstrating that citizen science can serve as an effective tool for students to engage in climate data collection and analysis actively (Bonney et al., 2015; Harker-Schuch and Bugge-Henriksen, 2013). Moreover, role-playing games and simulations, such as “Mock COP,” cultivate decision-making skills and foster an understanding of the political dimensions of climate negotiations. Teacher professional development must incorporate these innovative approaches to enhance educators’ effectiveness. Furthermore, climate education should integrate both natural and social sciences to elucidate the cause-and-effect relationships and factors contributing to climate change, as a solid understanding of these elements is essential for informed decision-making (Jones and Trier, 2008; Leichenko and O’Brien, 2020). The European Commission [European Commission, Directorate-General for Education, Youth, Sport and Culture (DG EAC), 2019] emphasizes the connection between climate education and the green transition within the labor market. In this context, universities should incorporate climate-related topics across all disciplines, rather than restricting them to the natural sciences alone. Moreover, the rising level of climate anxiety among young people can be transformed into proactive engagement if educational settings provide adequate support and coping strategies (Ojala, 2011). Alongside (Pihkala, 2020) introduces the concept of “eco-anxiety,” highlighting its relevance to educational practices. Education should not only foster knowledge but also emotional resilience by integrating cognitive and social–emotional skills. Some authors emphasize that initiatives centered on project-based learning create opportunities to develop social capital (Ruiz-Mallén et al., 2022). In Latin America, practices demonstrate that climate education frequently draws on local knowledge and methods for biodiversity conservation. This suggests that the cultural context is crucial for the effectiveness of educational models. Havea et al. (2020) investigate policies in the Pacific Islands and demonstrate that education can enhance climate resilience, provided that both state and local community efforts support it (Havea et al., 2020). Recent systematic reviews underscore that teacher capacity represents a significant bottleneck in climate education. Aguilar et al. (2025) reveal that, despite widespread political recognition of educators’ importance, both initial and ongoing qualification programs often fail to equip teachers with the essential pedagogical and interdisciplinary skills needed to teach climate topics effectively. These findings underscore the need for robust professional development systems that are crucial to transforming climate education from a theoretical framework into practical implementation in schools.

A notable research gap exists in Southeast Europe, characterized by a lack of systematic studies and policies regarding climate education. Despite clear guidelines and an expanding body of empirical evidence over the past few years, the range of reproducible tools for the comparative assessment of national education systems’ systemic readiness remains limited. Ideally, such a tool would aggregate policies, curricular integration, teacher capacity, resources, and assessment into a single metric. This study seeks to fill that gap by operationalizing ‘readiness’ through CERI, which aligns with contemporary frameworks and evidence.

This study employed a comprehensive analytical framework that encompasses a systematic literature review, documentary analysis, and expert evaluation facilitated by the Delphi method, alongside multi-criteria decision-making techniques, specifically the Analytic Hierarchy Process (AHP) and the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS). Such an integrative approach is commonly employed in research endeavors that aim not only to delineate conceptual trends but also to develop practical measurement instruments (Creswell and Plano-Clark, 2017). The tool created in the current study is the Climate Education Readiness Index (CERI), which evaluates the preparedness of five selected educational systems in Southeast Europe—namely, Bulgaria, Romania, Serbia, Greece, and Croatia—to incorporate climate education into their school curricula.

For each of the five countries, a targeted corpus of official strategic, regulatory, and programmatic documents relevant to education, climate policies, and sustainable development was compiled. This corpus includes national education strategies, curricula, regulations governing teacher qualifications and professional development, national climate strategies and action plans, and documents pertaining to the evaluation and monitoring of education systems. The selection of documents was based on their normative significance, national applicability, and direct relevance to the CERI indicators being measured. All sources are publicly accessible.

The coding procedure adhered to predefined guidelines: for each indicator, key concepts, criteria for minimum, average, and maximum values, and a stipulation for at least two independent confirmations within the document were established to achieve the highest rating. To ensure the reliability of the document coding, cross-coding was performed on 20% of the corpus by two researchers, who coded independently. Agreement was evaluated using Cohen’s κ (Cohen’s κ = 0.81), indicating high coding reliability. For each country, the corpus includes regulatory, strategic, and programmatic documents across education, climate policy, and sustainable development. The complete list of documents used, institutions, years, and official links is presented in Supplementary Table S1. The coding procedure is based on a pre-developed codebook with clearly defined indicator scales and assessment anchors, which ensures full reproducibility of the analysis (Supplementary Table S2).

Each document was matched with one or more of the six CERI dimensions (CI, TC, AA, RI, WS, PG), ensuring consistency between the document analysis and the index structure.

The Delphi method is a systematic approach for gathering and synthesizing expert opinions through multiple rounds of iteration. This method relies on a group of experts completing questionnaires anonymously, with the outcomes of each round summarized and returned to participants for further evaluation and analysis. This process fosters gradual convergence of viewpoints and helps establish consensus on the issue being examined (Hsu and Sandford, 2007; Okoli and Pawlowski, 2004). In the current study, the Delphi method was employed to define and validate the key dimensions and indicators of the Climate Education Readiness Index (CERI).

The Delphi panel was conducted online. Invitations to experts were sent by email, and responses were collected via Google Forms between February and May 2025. The procedure included two rounds: the first for validation/clarification of indicators and definitions; the second for consensus on relative importance (pairwise comparisons for AHP) and verification of wording. Participation was voluntary and anonymous; the results were analyzed in aggregate form.

The Analytic Hierarchy Process (AHP) was developed by Saaty (1987). It is a multi-criteria weighting technique that enables the structuring of complex problems in a hierarchical format. Its fundamental principle is to compare criteria or indicators pairwise to evaluate their relative significance (Saaty, 1987).

The analysis scores are subsequently transformed into numerical weights that quantitatively reflect each criterion’s contribution to achieving the overarching objective. The Analytic Hierarchy Process (AHP), a robust methodology for structuring multicriteria decision-making, has been effectively applied in education (Saaty, 1987). In the present study, AHP was employed to determine the relative weights of the six dimensions outlined in the Climate Education Readiness Index (CERI), thereby providing a quantitative representation of expert assessments and ensuring comparability across the selected countries.

Additionally, the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) was utilized as a complementary evaluation tool. TOPSIS assesses and ranks alternatives by calculating their proximity to an „ideal solution “and their distance from an „anti-ideal solution“. The application of this method entails normalizing the data, identifying both ideal and least favorable values for each criterion, and subsequently calculating the distances of each alternative from these extreme points. The resulting proximity coefficient provides a hierarchical ranking of the other options by overall effectiveness. In this study, TOPSIS was employed to validate the findings and rank the five countries based on their readiness for climate education, accounting for their strengths and weaknesses.

The research approach encompasses three primary stages: 1. Systematic Literature Review (SLR): Identification of dimensions and indicators. 2. Policy and Curriculum Analysis: Coding of official documents and curricula based on predefined indicators. 3. Delphi–AHP/TOPSIS: Validation of indicators through expert consensus, weighting, and index construction. The study unfolds in the following steps:

The systematic literature review was conducted using the Web of Science Core Collection and Scopus databases, covering the period from 2010 to 2024. A combination of keywords—climate change education, climate literacy, teacher training, curriculum integration, and green skills—was employed. Initially, 30,133 publications were identified. After removing duplicates, 19,482 unique sources remained. During the title and abstract screening stage, publications lacking an educational focus or having a strictly technological emphasis were excluded, resulting in 642 sources for full-text analysis. Ultimately, 52 articles that aligned with all inclusion criteria were included in the final analysis. The subsequent phase of the study involves applying thematic coding, a qualitative analytical technique designed to systematically explore textual data—in this instance, the selection of scholarly articles under review. Thematic coding entails a meticulous examination of the texts, which are annotated (coded) with key categories or themes. This methodology facilitates the identification of recurrent patterns, concepts, and trends within literature.

In this study, all 52 articles were imported into the Atlas.ti program, where they were subjected to coding based on principal themes in accordance with the framework. Each article was assigned a unique code, for instance, „teacher reform“. Similar codes were subsequently amalgamated into broader categories; for example, the codes “teacher barriers” and “lack of training” were synthesized into the overarching theme “Teacher Capacity Challenges”. This coding process resulted in the establishment of a thematic structure comprising six principal themes. The initial coding phase yielded over 120 distinct codes, which were later organized into six central themes aligned with the analytical framework of the Climate Education Readiness Index (CERI): 1. Curriculum Integration (CI); 2. Teacher Capacity (TC); 3. Assessment and Accountability (AA); 4. Resources and Infrastructure (RI); 5. Whole School and Community (WS); 6. Policy and Governance (PG). Table 1 shows some of the codes.

The primary codes obtained were systematically organized and categorized into thematic groups, which were then integrated into six main themes aligned with the analytical dimensions of the CERI index. Thematic coding facilitated a transparent, methodical transition from the qualitative content of the literature to the quantitative indicators used in the comparative analysis. To enhance reliability, the coding process was conducted independently by two researchers, resulting in a high level of agreement (Cohen’s κ = 0.82). This demonstrates that the extracted themes accurately reflect the predominant trends identified in the literature under review. Based on the coding process, we established 16 indicators (2–3 per dimension) utilizing content-appropriate scales for each indicator:

Qualitative (e.g., depth of integration; coordination between institutions): 0–3.

The selection of these indicators was informed by: (1) recurring codes identified in the System literature review; (2) international frameworks (UNESCO, OECD, EC/Green Skills); and (3) contributions from a Delphi panel. The values for the CERI index indicators are derived exclusively from official regulatory and strategic documents, including laws and state educational standards; national curricula; strategies and plans for education and sustainable development; assessment and external examination documents; catalogs of qualification programs; and national programs for funding and resource allocation. All sources are publicly accessible on the websites of the relevant ministries and agencies, and both the URL and date of access were recorded for each document. When information was missing or incomplete, we adhered to a conservative coding principle and sought a secondary official document for verification. For cases with ≤10% missing data, we employed median imputation (filling empty cells with a reasonable value) within the relevant dimension, as clearly delineated in the results tables, which include indicators, definitions, scales, and key sources. The definitions of the indicators, the scales utilized, and the primary data sources for operationalizing CERI are summarized in Table 2.

Clear assessment anchors were established for all indicators (on scales of 0–3 and 0–5) to ensure the comparability and reproducibility of coding. A score of 0 indicates the absence of the relevant policy or practice in national documents; a score of 1 denotes a limited or pilot presence; 2 reflects partial systematic implementation; and 3 signifies systematic and normatively enshrined application. For the five-point scale (0–5), a similar gradation is utilized, considering scope, institutional sustainability, and degree of implementation. The complete codebook, including detailed criteria for each indicator, examples of documentary evidence, and coding procedures, is available in Supplementary Table S2.

Normalization. For comparability, the indicators are normalized to [0,1] using min–max (benefit orientation):

x ij ′ = x ij − min ( x j ) max ( x j ) − min ( x j )

Reverse normalization is used for cost-type indicators.

This study employs an integrated methodology that combines a Delphi panel, Analytic Hierarchy Process (AHP), and the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) to create a Climate Education Readiness Index (CERI). This approach was selected for its ability to strike a balance between quantitative measurement and qualitative expert consensus.

The Delphi panel facilitates the involvement of experts from diverse fields, including universities, schools, NGOs, and government institutions, thereby validating indicators within the regional context.

While a similar combination of methods has been utilized in a limited number of prior studies, it has primarily been applied in the realms of sustainable development and policy. This study is pioneering in its application of this methodology to evaluate climate education within national school systems. The analysis encompasses five countries: Bulgaria (BG), Romania (RO), Serbia (RS), Greece (GR), and Croatia (HR). The following considerations justify the selection of these countries:

Regional affiliation: All five are part of Southeast Europe and share comparable historical and socio-economic characteristics.

The five countries selected provide a representative sample of regional trends, facilitating the creation of a pilot index that could potentially be expanded to include other countries in the future. Table 3 presents the normalized values for all 16 indicators across the five analyzed countries. Normalization to the range [0–1] enables comparability across scales and data types, with 0 representing the weakest observed performance and 1 the strongest.

Greece and Croatia exhibit the highest values, particularly in Curriculum Integration (CI), Teacher Capacity (TC), and Whole-School and Community (WS). In contrast, Bulgaria consistently demonstrates balanced results. Romania and Serbia display lower values, particularly in Resources and Infrastructure (RI) and Assessment and Accountability (AA), highlighting deficiencies in systematic evaluation mechanisms and limited infrastructure.

The indicators’ values were aggregated at the dimensional level using mean values, facilitating the profiling of each educational system. The average dimension scores obtained for each country are presented in Table 4.

Policy and Governance stand out as prominent dimensions across all countries, reflecting the presence of strategic documents and policies. In contrast, Assessment and Accountability is the least developed area, lacking a sustainable mechanism to evaluate climate competencies. Bulgaria exhibits a balanced profile, whereas Greece and Croatia demonstrate notable strengths in integration and community participation.

The relative importance of these dimensions was established using the Analytic Hierarchy Process (AHP). The weights assigned to the six dimensions (AHP weights) used in the CERI aggregation are presented in Table 5.

The prominent weights assigned to Teacher Capacity (0.22) and Policy and Governance (0.20) reflect expert consensus that high-quality teacher training and a stable policy framework are essential to successfully integrate climate education. Curriculum Integration (0.18) also serves as a crucial mechanism for content delivery. Conversely, the lower weights assigned to RI, WS, and AA suggest that while these dimensions are secondary, they remain essential for achieving systemic sustainability.

Following a summary of the indicator values at the dimension level (Table 4), notable differences are evident between countries. To illustrate this structure more clearly and to emphasize the strengths and weaknesses of each education system, the results are presented as a heatmap. The heat map of the results by dimension for the five countries is presented in Figure 1.

Figure 1 presents the normalized results (ranging from 0 to 1) across six dimensions for the five countries examined. Darker colors signify higher values. Greece clearly emerges as the frontrunner across all dimensions, while Serbia and Romania demonstrate comparatively lower performance, particularly in Resources and Infrastructure and Assessment and Accountability.

The final Climate Education Readiness Index (CERI) serves as a comprehensive measure of national education systems’ preparedness to incorporate climate education into their curricula. This index is computed by aggregating the six dimensions using weights derived from the Analytic Hierarchy Process (AHP), as detailed in Table 5. The values of the dimensions are based on the normalized indicator results presented in Table 4.

Calculation method:

Formally, the index for country i is calculated as:

CER I i = ∑ d = 1 6 w d ⋅ S d , i

In this context, \(w_d\) represents the weights derived from the Analytic Hierarchy Process (AHP), while \(S_{d, i}\) denotes the normalized results corresponding to each dimension. This methodology facilitates a structured aggregation in which each dimension’s contribution is aligned with its significance, as ascertained by the expert panel. The final index is calculated as the weighted sum of the dimensional results with the AHP weights.

Greece (0.64) leads the region, benefiting from a combination of robust political commitment (PG = 0.70), practical teacher training (TC = 0.60), and systematic integration of educational content into curricula (CI = 0.65). The alignment between the most significant factors and high-performance outcomes reinforces the overall impact. Bulgaria (0.56) presents a balanced profile, featuring strong policies (PG = 0.62) and stable teacher capacity (TC = 0.53), although its integration into curricula is somewhat more moderate (CI = 0.55). Croatia (0.54) focuses on whole-school initiatives and collaborative partnerships (WS = 0.50) but falls short in resource allocation (RI = 0.52). Romania (0.44) and Serbia (0.38) exhibit notable deficits in Resources and Infrastructure (RI) and Assessment and Accountability (AA), which constrain the effectiveness of their climate education policies. Upon calculating the final CERI index for each country (as shown in Table 6), the variances in readiness become particularly clear when visualized graphically. Figure 2 presents a bar chart comparing the five countries, highlighting their differences.

Figure 2 highlights Greece’s notable position with a score of 0.64, closely followed by Bulgaria at 0.56 and Croatia at 0.54. The significant disparity between these top three countries and Romania, which scores 0.44, and Serbia, at 0.38, underscores pronounced regional differences in readiness to integrate climate education. After presenting the final values of the CERI index (see Table 6 and Figure 2) one might wonder which dimensions contribute most to each country’s ranking. To provide clearer insight into the index’s internal structure, Figure 3 illustrates the relative contributions of each dimension to the overall results for Greece and Bulgaria—the top-ranked country and its runner-up, respectively.

The graph indicates that Policy and Governance and Teacher Capacity are the most crucial factors for Greece. In contrast, Bulgaria exhibits a more balanced contribution across dimensions, albeit with lower values in Curriculum Integration. This disparity explains why Bulgaria lags behind Greece, despite comparable values in other areas. The CERI index has several practical applications: 1. Comparative assessment: it enables countries to evaluate their standing relative to neighboring nations. 2. Policy benchmark: it highlights which dimensions are elevating performance and which are hindering it, guiding resource allocation toward the most critical weaknesses 3. Monitoring: the index can be periodically updated (e.g., every 3–5 years 4). Transfer of good practices: countries with lower indices can study the leaders in specific dimensions (e.g., HR in WS, GR in PG) and adapt their successful strategies.

The reliability of composite indices hinges not only on the appropriate calculation methodology but also on the stability of the rankings when alternative aggregation techniques are employed. To verify the stability of the CERI index, this study applied the TOPSIS (Technique for Order of Preference by Similarity to Ideal Solution) method. TOPSIS assesses the proximity of each alternative to the “ideal solution,” which represents the best values across all criteria, and its distance from the “anti-ideal solution,” characterized by the worst values. This method is commonly utilized in multi-criteria analyses and is recommended as a complementary approach to AHP for validating results. In this case, the outcomes of the TOPSIS analysis yielded the following proximity coefficients (C_i): Greece –0.68; Bulgaria –0.57; Croatia –0.55; Romania 0.45; Serbia –0.40.

The resulting ranking closely resembles that of the CERI index, with the only minor variation being the exchange of positions between Bulgaria and Croatia, which have very similar scores. The Spearman’s rank correlation coefficient between the two rankings is ρ = 0.95, indicating a very high level of consistency. This validation suggests that the final ranking is not merely an artifact of the chosen aggregation methodology; rather, it is stable and reproducible. Greece stands out as the clear leader, while Serbia is in last place, and Bulgaria and Croatia occupy intermediate positions. Although their positions may shift slightly depending on the methods employed, the overall picture remains unchanged. In addition to TOPSIS validation, a sensitivity analysis was conducted to assess the extent to which the results depend on the assigned weights for the dimensions. Such an approach is commonly employed in multi-criteria analyses (Ishizaka and Nemery, 2013). It is particularly recommended when weights are derived from expert assessments, as these may vary depending on panel composition or specific context. Methodologically, the weight of each dimension was increased by 20%, after which all weights were renormalized to keep the sum at 1. This simulates a scenario in which experts rate a given dimension as more important without altering the model’s overall structure. The tornado diagram (Figure 4) illustrates the variation in the CERI index for Bulgaria across different weightings. Teacher Capacity and Policy and Governance have the most significant impact on the index value, consistent with their leading roles in the AHP analysis. Changes in the weights of the other dimensions lead to minor variations, and the ranking of countries remains unchanged. This means that:

Even with a 20% change in weights, the positions of countries in the final ranking are stable.

The analysis results present a clear picture of the readiness to integrate climate education across the five countries studied. At the first level, 16 indicators were identified and aggregated into six dimensions through thematic coding and expert validation. At the second level, the dimensions were weighted using the AHP method, with Teacher Capacity and Policy and Governance receiving the highest weights. At the third level, the final CERI index ranked countries by their readiness, with Greece emerging as the leader and Bulgaria and Croatia forming a “middle group” with similar scores. Romania and Serbia lagged significantly behind due to weaknesses in resource provision and the lack of systematic evaluation mechanisms. The TOPSIS validation confirmed the robustness of the results, and the sensitivity analysis showed that the rankings remained consistent despite substantial changes in the weights. This demonstrates that CERI is a reliable tool for comparative assessments and can be used not only for academic research but also as an effective instrument for monitoring and shaping policies in climate education.

This study systematically evaluates the readiness of national education systems in five Southeast European countries to incorporate climate education and develops and applies the Climate Education Readiness Index (CERI).

The index is based on official national documents and expert assessments, meaning the results primarily reflect the institutional and political frameworks of education systems rather than classroom practices. This focus on system-level dynamics sets CERI apart from many existing approaches in the literature, which primarily evaluate students’ knowledge, attitudes, or specific curricular components rather than institutions’ overall readiness. This limitation highlights a key area for future empirical research.

The analysis highlighted a distinct divide between countries with more advanced levels of climate education readiness, such as Greece, Bulgaria, and Croatia, and those that are lagging, namely Romania and Serbia. This pattern suggests that the differences are more closely related to factors such as institutional coordination, policy continuity, and teacher professional development than to economic capacity alone. This divide is not entirely related to countries’ economic capacity, but rather to the political will and commitment of the institutions. Greece’s leading position reflects not only higher indicator values but also a coherent national climate governance framework that facilitates coordination among education policy, teacher training, curriculum reform, and assessment mechanisms. Serbia’s lower results are due to fragmented governance structures and weak coordination between education and climate policies, which hinder the systematic integration of climate issues into school curricula. Teacher capacity emerged as the most critical dimension, consistent with international studies. However, CERI expands this perspective by capturing not only teacher knowledge but also the availability of continuous professional development and policy-supported training frameworks within institutions. Despite policies, some countries lack sufficient investment in professional development, resulting in a “gap” between the strategic level and school practice. This highlights the need for systematic teacher training programs that are not just one-off courses but sustainable, adaptable mechanisms. The poor performance in the Assessment and Accountability dimension highlights that climate education assessment remains inadequately developed at the system level. This observation is consistent with recent literature, which shows that most existing tools primarily focus on cognitive knowledge instead of on institutional monitoring and accountability mechanisms. This is particularly concerning, as the absence of progress indicators hampers the ability to track policy effectiveness and compare outcomes with international best practices. Consequently, the findings highlight the need to develop assessment systems that encompass not only cognitive knowledge but also attitudes, values, and skills for action. The Whole-School and Community dimension yields average results, yet its significance should not be overlooked. In countries like Croatia, school initiatives and partnerships with NGOs and universities have fostered innovative practices that effectively address resource limitations. This model demonstrates how whole-school and community-based strategies can partially offset limited financial resources by enhancing institutional learning, partnerships, and social capital. The results imply that the successful integration of climate education requires a multifaceted approach, which includes:

Clear and consistent policies.

These elements must not be perceived in isolation; instead, they should be understood as interconnected components of a comprehensive strategy. The omission of any single element results in an imbalance that impedes the realization of significant transformation. From a theoretical perspective, this study advances the climate education literature by defining “systemic readiness” as a measurable concept, thereby shifting the analytical focus from individual outcomes to institutional capacity for long-term implementation.

The findings from CERI highlight teacher capacity as a critical dimension of system readiness, aligning with several recent international studies. Systematic reviews and synthesis analyses indicate that, despite policies and curricula, inadequate initial and ongoing teacher training remains a significant barrier to effective climate education. In this context, the current study reinforces these observations by framing them within an institutional readiness paradigm, evaluated through policies, programs, and systemic support rather than focusing solely on individual pedagogical practices (Aguilar et al., 2025).

In the context of Assessment and Accountability, the lower scores observed in some of the analyzed countries reflect a well-documented issue identified in the literature: the insufficient availability of reliable tools for assessing climate literacy. Current methodologies often emphasize cognitive knowledge while neglecting crucial aspects such as systems thinking, interdisciplinary competencies, and the willingness to take action. The CERI findings on this dimension not only align with but also empirically corroborate a structural shortfall identified in more recent frameworks and studies seeking to develop integrated assessment models (Martin et al., 2025).

A comparison of policy-oriented and curriculum-based analyses indicates that the mere presence of strategic documents and regulatory commitments does not ensure a high level of systemic readiness. Consistent with findings from other international studies, the CERI results highlight a disparity between the formal inclusion of climate issues in policies and their effective implementation within curricula. This study enhances these approaches by integrating document analysis and expert assessments into a cohesive index framework, enabling a more nuanced differentiation between the declarative and functional levels of readiness.

In summary, this study offers an integrated index of systemic readiness that aggregates policies, instructional integration, teacher capacity, resources, and assessment into a cohesive analytical framework. Unlike a substantial portion of existing research that primarily focuses on individual learning outcomes or the effects of specific interventions, this approach does not replace micro-level studies. Instead, it complements them by providing a valuable tool for comparative analysis across countries and for monitoring progress over time.

This study developed and applied the Climate Education Readiness Index (CERI) to evaluate the preparedness of education systems to incorporate climate education. The index integrates findings from a systematic literature review, documentary analysis, and expert assessments employing the Delphi, AHP, and TOPSIS methods. By doing so, it presents an innovative and reliable approach to comparing various countries and identifying their strengths and weaknesses in their strategies. The analysis of five countries in Southeast Europe revealed that the readiness for climate education varies significantly and is heavily influenced by institutional and political factors. Greece emerged as the top performer, boasting the highest index, attributed to a consistent policy framework and focused efforts to enhance teacher capacity. Bulgaria and Croatia occupy the middle tier with balanced results, showing potential for improvement through more systematic evaluation and better resource allocation. Romania and Serbia continue to be positioned on the periphery of the integration process, suggesting that, without strategic initiatives and targeted investments, the incorporation of climate education will remain minimal. The theoretical contribution of this study lies in the development of a measurement tool that combines qualitative and quantitative indicators and can be tailored to various contexts. The CERI index enhances existing methodologies by providing a transparent, reproducible framework for integrating expert opinions and documentary analysis. The methodological contribution is evident in the combination of Delphi, AHP, and TOPSIS—a rare approach in education that demonstrates its applicability and sustainability. The practical implications of this study are particularly noteworthy. The index can serve as a valuable tool for:

Monitoring national policies and programs within a dynamic context.

The study emphasizes that teacher capacity and political commitment are fundamental to the success of climate education. Moreover, the lack of systematic assessment mechanisms is a notable weakness that needs to be addressed by developing climate literacy indicators and incorporating them into national examination systems. While the study has its limitations—namely, it focuses on only five countries and relies on a fixed set of indicators —it provides a valuable foundation for future research. Subsequent efforts could expand the scope to encompass additional countries, integrate more indicators (including those related to digital innovation and social inequalities), and regularly update the index to track progress over time. In conclusion, the CERI index is a practical and scientifically robust tool that can benefit both the academic community and policymakers alike. It not only evaluates the readiness of education systems but also identifies critical areas for intervention. By aligning policies, resources, teacher competency, and community engagement, countries in Southeast Europe—and beyond—can harness climate education as a driving force for sustainable transformation. Based on the study’s findings and the analysis of the CERI index, several recommendations can be proposed for policymakers, educational institutions, and international organizations. These recommendations are designed to facilitate the systematic and sustainable integration of climate education into national education systems. It is essential that climate education be incorporated as a mandatory element in national education strategies and sustainable development plans. This integration requires establishing clear objectives, identifying responsible institutions, and implementing accountability mechanisms. Moreover, teachers should be placed at the forefront of this transformation. Countries must develop ongoing professional development programs to ensure that all educators have access to current knowledge and effective pedagogical tools for incorporating climate-related topics into their curricula. These programs should be sustainably funded, rather than relying on short-term project financing. Indicators and standardized mechanisms for evaluating climate literacy should be implemented. This framework should include not only knowledge assessments but also tools for measuring skills, attitudes, and the willingness to act. Such measures will ensure that advancements in climate education are both trackable and quantifiable. Governments and local authorities ought to establish incentives for schools that incorporate sustainability into all aspects of their operations—from curricula to resource management and community involvement. Even small grant programs that promote innovative practices at the school level can have a significant impact. Collaboration among schools, universities, NGOs, and international organizations should be regarded as a strategic priority. These partnerships can offer access to essential resources, expertise, and innovative teaching methodologies that facilitate the integration of climate education. Countries in Southeast Europe stand to gain considerably from the exchange of best practices and collaborative initiatives. Establishing regional networks for climate education would foster synergies and enable a more efficient utilization of limited resources.