ScholarWorks@중앙대학교

초록

This study investigates the topical composition of the IPCC Synthesis Reports’Summaries for Policymakers (SPMs) from the Third Assessment Report (TAR) through the Sixth (AR6). Employing a mixed-method approach that integrates Latent Dirichlet Allocation (LDA) topic modeling and log-ratio-based text scatterplot visualization, the study aims to uncover shifts in both topical composition and linguistic emphasis over time. LDA topic modeling reveals a noticeable transition from the early emphasis on physical and natural science-based explanations to more recent attention toward climate policy and action, mitigation, adaptation, and governance. To determine whether these apparent shifts reflect statistically meaningful trends, the study applies bootstrapping and ANOVA, including a five-sentence chunk-based analysis, to topic proportions across reports. The results show significant difference in topics related to ‘physical influence of climate change’ and ‘climate policy and action,’ highlighting the change of topic focus in AR6. The log-ratio visualization further identifies words that experienced prominent increase or decrease in usage across reporting periods. Importantly, it allows the detection of conceptually salient terms that are not necessarily frequent but are strongly associated with a specific temporal or discursive context. This analysis captures the emergence of new framing devices (e.g., “net zero,” “climate resilient development”) and the disappearance of outdated terms (e.g., “SRES,” “stabilization”). Together, these findings contribute to a deeper understanding of the expansion, evolution, and diversification of climate science over time, reflecting the accumulation of scientific evidence, the shift of priorities, and the growing urgency of global climate governance.

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