Centralized hashtags, embedded discourse: Two structural logics of youth climate activism on social media

Youth-led climate action increasingly unfolds on digital platforms, where hashtags structurally connect issues, actors, and publics. Using hashtag co-occurrence data (2022–2024) from prominent youth climate activists on X and Portuguese youth climate activists on Instagram, this study applies link community analysis, which captures overlapping multi-membership structures that node-based clustering obscures. Two contrasting structural logics emerge. The international network exhibits a centralized configuration in which core climate hashtags such as #FridaysForFuture and #Peoplenotprofit occupy bridging positions across issue communities, so that visibility and structural centrality closely align. The Portuguese network displays a more horizontal configuration in which climate-related hashtags co-occur with feminism, education, domestic politics, and art-based activism, embedding climate discourse within everyday publics. Digital climate publics take shape as relational structures produced through patterns of hashtag overlap and cross-issue connectivity.