Academics have traditionally played a vital role in both the generation and dissemination of knowledge, ideas and narratives. Social media, relative to traditional media, provides for new and more direct ways of science communication. Yet, since not all academics may engage with social media, the sample that does so may have an outsize influence on shaping public perceptions of academia more broadly through at least two channels: the set topics they engage with and through the particular style and tone of communication. This paper describes patterns in academics' expression online found in a newly constructed global dataset covering over 100,000 scholars linking their social media content to academic record. We document large and systematic variation in politically salient academic expression concerning climate action, cultural, and economic concepts. We show that these appear to often diverge from general public opinion in both topic focus and style. 

The study measures scientists’ polarization on social media and its impact on public perceptions of their credibility. Analyzing 98,000 scientists on Twitter from 2016 to 2022 reveals significant divergence in expressed political opinions. An experiment assesses the impact of online political expression on a representative sample of 1,700 U.S. respondents, who rated vignettes with synthetic academic profiles varying scientists’ political affiliations based on real tweets. Politically neutral scientists are viewed as the most credible. Strikingly, on both the ’left’ and ’right’ sides of politically neutral, there is a monotonic penalty for scientists displaying political affiliations: the stronger their posts, the less credible their profile and research are perceived, and the lower the public’s willingness to read their content. The penalty varies with respondents’ political leanings.