What Drives Climate Sentiment on Twitter/X? Climate Disasters, Climate Policy, or Political Debate?

Social media platforms have become central arenas for climate communication, shaping how climate-related issues are discussed, interpreted, and contested. While previous studies have examined online responses to predefined climate events, less is known about which types of events generate the strongest shifts in climate-related sentiment. This study investigates the drivers of climate sentiment on Twitter/X using more than 100,000 climate-related tweets posted between 2015 and 2026. The study applies a discourse-centred analytical framework combining sentiment analysis, event detection, external event validation, and topic modelling. Twitter-RoBERTa was used to construct a daily sentiment time series, from which 244 candidate sentiment peaks were identified. The ten highest-impact peaks were then compared with documented climate disasters and international climate policy events and analysed using LDA topic modelling. The results show that major sentiment shifts were only weakly associated with documented climate disasters and COP-related policy events. Instead, political actors, political debate, climate skepticism, media narratives, and public controversy were more prominent drivers of sentiment change. Topic analysis further showed that physical climate impacts were present in the wider discussion context but were rarely the dominant focus. The findings highlight the central role of political and media dynamics in shaping online climate sentiment.