In this study, we examine if exposure to justifications for and against climate action affects citizens’ tolerance toward others. Specifically, we assume that regularly encountering pro and con climate action arguments triggers reflective thinking (i.e., internal deliberation), which then increases tolerance. Based on a 3-wave panel survey in the United States, Spain, and Germany (NW1 = 4,706; NW2 = 3,622; NW3 = 2,654), we find empirical support for the role of internal deliberation as a mediator of the effect of political argument exposure on tolerance. In line with our theoretical model, path analyses show that the frequency of experienced argument exposure fosters internal deliberation in all countries, which—in the United States and Germany—indirectly increases tolerance, depending, however, on the tolerance measure used. Overall, we do not find substantial total effects of argument exposure on tolerance in the specific context of climate action, pointing to entrenched positions. In the United States, balanced exposure can even produce backlash effects, that is, negative total effects on tolerance. Exploratory analyses indicate that climate action argument exposure effects on internal deliberation and political tolerance are highly group specific, pointing to the role of contextual factors in shaping this relationship.