In the era of globalization and digitalization, this study employs transfer entropy and data mining to analyze climate information flows before and after China’s dual-carbon target. The analysis is based on 904,837 posts collected from 2019 to November 2021, including 17,380 original posts, 767,171 first-layer retweets, and 120,286 second-layer retweets, and combines Latent Dirichlet Allocation (LDA) topic modeling, Bidirectional Encoder Representations from Transformers (BERT)-based emotion classification, information entropy, and transfer entropy. Results show a policy-driven topic shift from “climate reporting” to “carbon neutrality” following the policy announcement, accompanied by changes in the distribution of public emotions, including greater visibility of anger and sadness in some dissemination layers. Government and celebrities dominate agenda-setting, while emotional polarization among ordinary and talent users indicates hierarchical differences in aggregate emotional expression. During diffusion, emotional expression shifted from positive toward negative categories, a pattern that is consistent with an “emotional cycle effect”. Geographic differences were observed in climate-related posting activity and emotional expression. Information entropy differed across dissemination layers, indicating changes in the diversity and uncertainty of emotional distributions. These insights can inform more effective climate-policy communication and dissemination strategies.



