Chalmers Conferences, 9th European Conference on Mathematical and Theoretical Biology

Collective-Risk dilemmas and Risky Climate Game
Maria Abou Chakra

Last modified: 2014-06-09


A collective-risk social dilemma arises when a group must cooperate to reach a common target in order to avoid
the risk of collective loss while each individual is tempted to free-ride on the contributions of others. In contrast to
the prisoners' dilemma or public goods games, the collective-risk dilemma encompasses the risk that all individuals
lose everything. These characteristics have potential relevance for dangerous climate change and other risky social
dilemmas. Climate change relief is truly the most influential cooperative act we can be a part of, especially since our decisions now may influence the decisions of future generations.
However, collaborative prospects are disheartening due to the uncertainties associated with Climate change and the diversity of the actors involved (eg. wealth). Cooperation is costly to the individual and it only benefits all individuals if the common target is reached.
An individual thus invests without guarantee that the investment is worthwhile for anyone. If there are several subsequent
stages of investment, it is not clear when individuals should contribute. Thus, in this game, the timing of contributions becomes a strategic variable that allows individuals to interact and influence one another. Herein, we investigate the strategic behavior using an evolutionary model of such collective-risk dilemmas in a finite population; every individual takes part in many games and successful behaviors spread in the population. Individual contributions depend on the stage of the game and on the sum of contributions made so
far. Thus far prediction have shown that, the best strategy was to `wait and see'. This was consistent under homogeneity, heterogeneity, target uncertainty, across round number and various group sizes. However one key difference in heterogeneity, the rich players contribute in excess in oder to compensate for the missing contributions of the poor. The rich can contribute more because they possess more, simulations show that as heterogeneity increases, rich contributions also increase. In our model, we do not assume rationality and the agents do not have a sense of fairness. Our results show, rich individuals will contribute more since they have more to loose. It is in their best interest to meet the target, even if it also benefits everyone else.


Public good, social dilemmas, evolutionary dynamics