Reactions to warnings in the climate commons

People receive daily environmental warnings about the risk of reaching critical climate tipping points leading to irreversible consequences. However, little is known about whether such warnings promote behavioral change, or how emotions underlie such responses. Here, we present two preregistered online experiments, in which group members can harvest financial resources from a common pool while risking collective over-exploitation causing an actual environmental externality. We find that warnings are effective and that the self-conscious emotion guilt consistently correlates with (Study 1) and mediates (Study 2) the effect of warnings on sustainable behavioral change. This suggest that warnings, as a lever of experienced guilt, may qualify as an effective strategy to promote cooperation in the climate commons.