Polarization in an Evolving Social Media Landscape: Multimodal Insights from the Climate Debate

Polarization of opinions in contemporary societies, particularly on social media, has become a central concern in academic and institutional settings, especially because of its association with misinformation, communicative breakdowns, and toxic exchanges. Although this phenomenon has been widely examined, two aspects of polarization require further attention.
The first aspect concerns the fact that polarization in public debates is often shaped by underlying social cleavages that bring into confrontation groups that differ in their socioeconomic backgrounds, belief systems, moral frameworks, and even psychological orientations. These substantial divergences can in turn shape the way in which each side communicates and presents its views. As these communicative differences manifest, they can exacerbate hostility and undermine opportunities for constructive dialogue. This makes it essential to systematically analyse these communicative divergences in order to understand how they shape both the articulation of positions and the audience reactions they give rise to.
A second aspect involves the shifting architecture of contemporary platforms. Social media environments are increasingly characterized by the proliferation of visual formats, which now play a central role in the production, circulation, and reception of political messages. This visual turn reconfigures both the affordances available to users and the dynamics through which political meaning is produced and contested, with inevitable implications for the ways polarized conflicts emerge and persist online. Under these conditions, in order to keep pace with the current evolution of digital platforms, we need analytical strategies that allow us to capture the role of visual formats in shaping online debates.
To examine these two dimensions in a concrete research setting, the dissertation takes the climate change debate as its empirical focus. This issue represents a salient contemporary cleavage, marked by sustained public attention, pronounced stakeholder divisions, and extensive use of multimodal communication. Within this context, the dissertation advances a twofold
contribution. Methodologically, it introduces computational tools for analysing multimodal communication in social-media settings, including automated ideological detection from textual content and semantic categorization of visual material. Empirically, it shows that the two sides of the climate debate diverge in both their textual communication styles and the visual themes they propagate, and that these discursive differences are reflected in systematic variations in
audience engagement.