In response to the urgent global climate crisis, climate activism has risen as a potent force. Decision-making regarding climate collective action includes individuals' perceptions of the anticipated future existential risks of the climate crisis (risk of inaction) and present-day political risks of climate activism (risk of action). Our research, spanning four studies (two correlational surveys and two pre-registered experiments), focused on climate activism in Germany (N = 1027). We consistently showed that heightened politicized activist identification was associated with both confrontational and non-confrontational climate collective action across four studies. Furthermore, the anticipated existential climate risk was associated with non-confrontational climate action and present-day political risk with confrontational action. Politicized climate identity remained a robust predictor across different action tactics, while the content and temporality of risk (future existential vs. present-day political) in one's environment determined the transition between engagement in confrontational and non-confrontational climate action dynamically. Nevertheless, we did not find causal links between risk perceptions and collective action. We discuss our findings in line with ESIM (Elaborated Social Identity Model), and potential explanations for the lack of causal relationship and future directions for alternative methodologies and comprehensive conceptualization of risk perceptions are suggested.