Sustaining local commons in the face of uncertain ecological thresholds: Evidence from a framed field experiment with Colombian small-scale fishers

Due to climate change abrupt and persistent changes in ecosystems, impacting millions of livelihoods, are likely but hard to predict. How people respond to such uncertain 'regime shifts' is poorly understood. Here, we assess the potential for local collective action to avert uncertain, yet catastrophic, regime shifts using behavioural economic experiments with 256 small-scale fishers from the Colombian Caribbean coast. With a framed, dynamic common-pool resource game, we tested the effect of different degrees of uncertainty (risk, ambiguity, certainty) about the existence of climate-induced thresholds on group exploitation patterns. Results from four different communities show that groups uncertain about thresholds are likely to sustain higher stock levels, thus poten-tially averting regime shifts. We also find that threshold uncertainty does not influence exploitation beyond thresholds. However, catch inequalities in the game, and community-level factors influence such exploitation, and appear to limit or even eliminate treatment effects; highlighting the significant influence of context on behaviour. Contrasting previous evidence, our results suggest to focus less on determining precise threshold likelihoods, but rather on identifying and communicating what ecosystem variables might have thresholds, and their potential consequences. Hence, we provide a more hopeful outlook given the irreducible uncertainties in relation to global environmental change.