(Un)certainty in science and climate change: a longitudinal analysis (2014–2022) of narratives about climate science on social media in Brazil (Instagram, Facebook, and Twitter)

This article examines climate change discourse on Brazilian social media from 2014 to 2022 and use a longitudinal approach, analyzing discourse, scientific authority, and eco-emotions on Instagram, Facebook, and Twitter. Methods include TF-IDF for feature extraction, sentiment analysis with VADER, and Named Entity Recognition (NER). A Ridge Classifier was trained on 557 manually classified samples. Findings show no significant increase in challenges to scientific authority or skepticism, but reveal a subtle shift towards using uncertainty as a rhetorical tool to undermine trust in scientific discourse.