Individuals can support climate-change mitigation in many ways, e.g., through private-sphere behaviors or the support of political measures. We assume that the common climate-change-mitigation heuristic of restriction does not sufficiently support impactful mitigation intentions and therefore introduce and investigate a new heuristic (optimization heuristic.) In a cross-sectional survey with N = 1427 participants (representative of the German population with regard to age, gender, education), we developed two scales to measure the heuristics of restriction and optimization. As individual climate-change-mitigation intentions, we recorded four types of private-sphere behavior, activism, and three forms of policy support. Further psychological variables (personal norm, biospheric value orientation) and sociodemographic variables were recorded. The factorial structure of all concepts was assessed by means of confirmatory factor analyses. Hierarchical regression analyses with the climate-change-mitigation intentions as the criterion were carried out. Results support the assumption of two related, yet distinct, climate-change-mitigation heuristics that were highly correlated with biospheric value orientation. We additionally computed measure of the dominance of the restriction heuristic. This variable had no correlation with biospheric values, and correlated with the intentions in the expected ways, indicating that individuals with a dominant restriction heuristic tend to show lower scores of impactful climate-change-mitigation intentions.