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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 potentially 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. [ABSTRACT FROM AUTHOR]

Many ecosystems can experience regime shifts: surprising, large and persistent changes in the function and structure of ecosystems. Assessing whether continued global change will lead to further regime shifts, or has the potential to trigger cascading regime shifts has been a central question in global change policy. Addressing this issue has, however, been hampered by the focus of regime shift research on specific cases and types of regime shifts. To systematically assess the global risk of regime shifts we conducted a comparative analysis of 25 generic types of regime shifts across marine, terrestrial and polar systems; identifying their drivers, and impacts on ecosystem services. Our results show that the drivers of regime shifts are diverse and co-occur strongly, which suggests that continued global change can be expected to synchronously increase the risk of multiple regime shifts. Furthermore, many regime shift drivers are related to climate change and food production, whose links to the continued expansion of human activities makes them difficult to limit. Because many regime shifts can amplify the drivers of other regime shifts, continued global change can also be expected to increase the risk of cascading regime shifts. Nevertheless, the variety of scales at which regime shift drivers operate provides opportunities for reducing the risk of many types of regime shifts by addressing local or regional drivers, even in the absence of rapid reduction of global drivers. [ABSTRACT FROM AUTHOR]