Processing information on the negative consequences of climate change can have unrelated side-effects such as increased outgroup derogation. Previous research suggests differing theoretical explanations for these “spill-over” effects such as buffering existential anxiety. Here, we test and compare two alternative explanations based on social dominance theory and the group-based control model. Across two pre-registered experiments (N = 1031; USA & UK), we examine whether social dominance orientation (SDO) and/or ingroup identification moderate the relationship between experimentally induced collective threats (i.e., climate change and intergroup threat) and subjective threat perceptions, modern racism, and pro-environmental collective action support. In Study 1, SDO and ingroup identification were measured 2 years prior to our experiment as antecedents of threat perceptions. Our results suggest that informing individuals about negative consequences of climate change (e.g., wildfires, floods, resource scarcity, health etc.), leads to higher intergroup threat perceptions and modern racism. These spill-over effects, in turn, are moderated by SDO but not by ingroup identification. In Study 2, we successfully replicate our findings, measuring SDO and ingroup identification directly after the threat manipulation. Moreover, we use a behavioral measure of pro-environmental collective action to assess more direct stimuli-responses. In Study 2, again, we show that SDO moderates the spill-over effects. In contrast, ingroup identification showed only marginally significant spill-over effect moderation and did not increase in response to experimental threat-cues. Notably, we also find that intergroup threat-cues generalize onto higher climate change threat perceptions. No effects on behavioral collective action support were found.