Extending preceding environmental discounting studies, we examined the role of response efficacy (in low, control, and high conditions) in participants’ valuation of climate-change concern and action across four psychological distance dimensions (temporal, spatial, social, and probabilistic). Participants gave ratings of concern and action in the context of two hypothetical scenarios which were directly related to two different threats (droughts and floods) posed by unmitigated climate change. Rachlin’s hyperboloid discount functions fit the data well. The previously observed gap between concern and action ratings was not replicated in the main analyses, but was seen in the ratings at the minimum distance values. Response efficacy differentially affected ratings of concern and action at the minimum distance values for the temporal, social, and probabilistic dimensions, but differentially affected discount values (k) only for the probabilistic dimension. Compared to their level of concern with the environmental threat, participants who were led to believe that their actions were not efficacious were less willing to engage in mitigation behaviors than participants who were led to believe that their actions were efficacious. The insights gained through the current research effort may be valuable for policymaking as well as intervention design aiming to increase societal mitigation and adaptation efforts.