Among nowadays collective action problems, the climate change, i.e. the responsible of natural disasters such as flooding, desertification, ecosystem and habitat destruction, represents one of the most important challenges of our century. Considering the climate as a non-excludable good we inevitably incur in the well-known outcome of the tragedy of the commons. In fact, when attempting to avoid global warming, individuals face a social dilemma in which, besides securing future benefits, it is also necessary to reduce the chances of future losses. Unfortunately, individuals, regions or nations may opt to be free riders, hoping to benefit from the efforts of others while choosing not to make any effort themselves. Pioneering work by Barrett [1–3] proposes a theory of full international cooperation that can be applied to the climate change problem. His findings provide a formal proof that only a “small” number of countries can sustain full cooperation by means of self-reinforcing environmental agreements. More importantly, his work shows that the constraint on international cooperation is free-rider deterrence, not treaty compliance enforcement. This last evidence is also supported in [4, 5], showing the importance of sanctions against free-riders for accomplishing cooperative climate agreements. A recent theoretical model has been proposed by the 2018 Nobel laureate Nordhaus on the formation of coalitions, or clubs, suggesting efficient solutions to tackle the dilemma and achieving high cooperation level outcomes [6]. At the individual level, social norms, defined as informal behavioural rules that are supported by empirical and normative expectations and potentially backed by enforcement [7], seem to be a promising way of helping solving climate change games situations in local interactions, but no experiments have been performed to measure them in this framework. The experimental setup that I will present is strictly related to the recent work by Nordhaus [6]. The basic idea is that international cooperative treaties can be achieved through the formation of climate clubs, i.e. coalitions of countries committed to abate their carbon fossil emissions, that sanction, by the implementation of harsher taxation regimes, countries outside the coalition. We investigate whether this simple theoretical mechanism can be applied to collective action problems when human participants, and not countries, are involved. 2 The experimental design is a repeated climate change game where each round is composed by three stages. In the first one participants pledge their participation to the climate club, in the second one they ratify it according to the number of other committed participants while in the last one they decide their contribution amount (considering that club members cannot free-ride). As in previous work, the disaster impact depends on the total contribution value but, now, club members also benefit from sanctions at expenses of non-member participants. Theoretical models predict that two Nash equilibria are present and can be reached more easily, or not, depending game parameters. In fact, the introduction of a sanctioning/rewarding system modifies the setup from a cooperation scenario to a coordination one. Accordingly, individuals can thus coordinate their actions to either full contribution or none.