Alessandro Tavoni

Inequality, communication, and the avoidance of disastrous climate change in a public goods game

International efforts to provide global public goods often face the challenges of coordinating national contributions and distributing costs equitably in the face of uncertainty, inequality, and free-riding incentives. In an experimental setting, we distribute endowments unequally among a group of people who can reach a fixed target sum through successive money contributions, knowing that if they fail, they will lose all their remaining money with 50% probability. In some treatments, we give players the option to communicate intended contributions. We find that inequality reduces the prospects of reaching the target but that communication increases success dramatically. Successful groups tend to eliminate inequality over the course of the game, with rich players signaling willingness to redistribute early on. Our results suggest that coordination-promoting institutions and early redistribution from richer to poorer nations are both decisive for the avoidance of global calamities, such as disruptive climate change.

Regime shifts in a social-ecological system

Ecological regime shifts are rarely purely ecological. Not only is the regime shift frequently triggered by human activity, but the responses of relevant actors to ecological dynamics are often crucial to the development and even existence of the regime shift. Here, we show that the dynamics of human behaviour in response to ecological changes can be crucial in determining the overall dynamics of the system. We find a social–ecological regime shift in a model of harvesters of a common-pool resource who avoid over-exploitation of the resource by social ostracism of non-complying harvesters. The regime shift, which can be triggered by several different drivers individually or also in combination, consists of a breakdown of the social norm, sudden collapse of co-operation and an over-exploitation of the resource. We use the approach of generalized modeling to study the robustness of the regime shift to uncertainty over the specific forms of model components such as the ostracism norm and the resource dynamics. Importantly, the regime shift in our model does not occur if the dynamics of harvester behaviour are not included in the model. Finally, we sketch some possible early warning signals for the social–ecological regime shifts we observe in the models.

The survival of the conformist: social pressure and renewable resource management.

This paper examines the role of other-regarding behavior as a mechanism for the establishment and maintenance of cooperation in resource use under variable social and environmental conditions. By coupling resource stock dynamics with social dynamics concerning compliance to a social norm prescribing non-excessive resource extraction in a common pool resource, we show that when reputational considerations matter and a sufficient level of social stigma affects the violators of a norm, sustainable outcomes are achieved. We find large parameter regions where norm-observing and norm-violating types coexist, and analyze to what extent such coexistence depends on the environment.

Robustness of norm-driven cooperation in the commons

Sustainable use of common-pool resources such as fish, water or forests depends on the cooperation of resource users that restrain their individual extraction to socially optimal levels. Empirical evidence has shown that under certain social and biophysical conditions, self-organized cooperation in the commons can evolve. Global change, however, may drastically alter these conditions. We assess the robustness of cooperation to environmental variability in a stylized model of a community that harvests a shared resource. Community members follow a norm of socially optimal resource extraction, which is enforced through social sanctioning. Our results indicate that both resource abundance and a small increase in resource variability can lead to collapse of cooperation observed in the no-variability case, while either scarcity or large variability have the potential to stabilize it. The combined effects of changes in amount and variability can reinforce or counteract each other depending on their size and the initial level of cooperation in the community. If two socially separate groups are ecologically connected through resource leakage, cooperation in one can destabilize the other. These findings provide insights into possible effects of global change and spatial connectivity, indicating that there is no simple answer as to their effects on cooperation and sustainable resource use.

Reserves and trade jointly determine exposure to food supply shocks

While a growing proportion of global food consumption is obtained through international trade, there is an ongoing debate on whether this increased reliance on trade benefits or hinders food security, and specifically, the ability of global food systems to absorb shocks due to local or regional losses of production. This paper introduces a model that simulates the short-term response to a food supply shock originating in a single country, which is partly absorbed through decreases in domestic reserves and consumption, and partly transmitted through the adjustment of trade flows. By applying the model to publicly-available data for the cereals commodity group over a 17 year period, we find that differential outcomes of supply shocks simulated through this time period are driven not only by the intensification of trade, but as importantly by changes in the distribution of reserves. Our analysis also identifies countries where trade dependency may accentuate the risk of food shortages from foreign production shocks; such risk could be reduced by increasing domestic reserves or importing food from a diversity of suppliers that possess their own reserves. This simulation-based model provides a framework to study the short-term, nonlinear and out-of-equilibrium response of trade networks to supply shocks, and could be applied to specific scenarios of environmental or economic perturbations.

Coordination Under Threshold Uncertainty in a Public Goods Game

We explored experimentally how threshold uncertainty affects coordination success in a threshold public goods game. Whereas all groups succeeded in providing the public good when the exact value of the threshold was known, uncertainty was generally detrimental for the public good provision. The negative effect of threshold uncertainty was particularly severe when it took the form of ambiguity, i.e. when players were not only unaware of the value of the threshold but also of its probability distribution. Early signaling of willingness to contribute and share the burden equitably helped groups in coping with threshold uncertainty.

The Survival of the Conformist: Social Pressure and Renewable Resource Management

This paper examines the role of other-regarding behavior as a mechanism for the establishment and maintenance of cooperation in resource use under variable social and environmental conditions. By coupling resource stock dynamics with social dynamics concerning compliance to a social norm prescribing non-excessive resource extraction in a common pool resource, we show that when reputational considerations matter and a sufficient level of social stigma affects the violators of a norm, sustainable outcomes are achieved. We find large parameter regions where norm-observing and norm-violating types coexist, and analyze to what extent such coexistence depends on the environment.

Delegation and Public Pressure in a Threshold Public Goods Game: Theory and Experimental Evidence

The provision of global public goods, such as climate change mitigation and managing fisheries to avoid overharvesting, requires the coordination of national contributions. The contributions are managed by elected governments who, in turn, are subject to public pressure on the matter. In an experimental setting, we randomly assign subjects into four teams, and ask them to elect a delegate by a secret vote. The elected delegates repeatedly play a one shot public goods game in which the aim is to avoid losses that can ensue if the sum of their contributions falls short of a threshold. Earnings are split evenly among the team members, including the delegate. We find that delegation causes a small reduction in the group contributions. Public pressure, in the form of teammatesi¯ messages to their delegate, has a significant negative effect on contributions, even though the messages are designed to be payoffinconsequential (i.e., cheap talk). The reason for the latter finding is that delegates tend to focus on the least ambitious suggestion. In other words, they focus on the lower of the two public good contributions preferred by their teammates. This finding is consistent with the prediction of our model, a modified version of regret theory.

Tipping Points and Loss Aversion in International Environmental Agreements

We study the impact of loss-aversion and the threat of catastrophic damages, which we jointly call threshold concerns, on international environmental agreements. We aim to understand whether a threshold for dangerous climate change is as an effective coordination device for countries to overcome the global free-riding problem and abate sufficiently to avoid disaster. We focus on loss-averse countries negotiating either under the threat of either high environmental damages (loss domain), or low damages (gain domain). Under symmetry, that is when countries display identical degrees of threshold concern, we show that such beliefs have a positive effect on reducing the emission levels of both signatories to the treaty and non-signatories, leading to higher global welfare and weakly larger coalitions of signatories. We then introduce asymmetry, by allowing countries to differ in the degree of concern about the threat of disaster. We show that stable coalitions are mostly formed by the countries with higher threshold concern. When enough countries having no threshold concern could cause the coalition size to diminish, regardless of the other countries have strong or mild threshold concerns.

Climate negotiators/' and scientists/' assessments of the climate negotiations

Climate negotiation outcomes are difficult to evaluate objectively because there are no clear reference scenarios. Subjective assessments from those directly involved in the negotiations are particularly important, as this may influence strategy and future negotiation participation. Here we analyze the perceived success of the climate negotiations in a sample of more than 600 experts involved in international climate policy. Respondents were pessimistic when asked for specific assessments of the current approach centered on voluntary pledges, but were more optimistic when asked for general assessments of the outcomes and usefulness of the climate negotiations. Individuals who are more involved in the negotiation process tended to be more optimistic, especially in terms of general assessments. Our results indicate that two reinforcing effects are at work: a high degree of involvement changes individuals’ perceptions and more optimistic individuals are more inclined to remain involved in the negotiations.