Simulating institutional heterogeneity in sustainability science.

Sustainability outcomes are influenced by the laws and configurations of natural and engineered systems as well as activities in socio-economic systems. An important subset of human activity is the creation and implementation of institutions, formal and informal rules shaping a wide range of human behavior. Understanding these rules and codifying them in computational models can provide important missing insights into why systems function the way they do (static) as well as the pace and structure of transitions required to improve sustainability (dynamic). Here, we conduct a comparative synthesis of three modeling approaches- integrated assessment modeling, engineering-economic optimization, and agent-based modeling-with underexplored potential to represent institutions. We first perform modeling experiments on climate mitigation systems that represent specific aspects of heterogeneous institutions, including formal policies and institutional coordination, and informal attitudes and norms. We find measurable but uneven aggregate impacts, while more politically meaningful distributional impacts are large across various actors. Our results show that omitting institutions can influence the costs of climate mitigation and miss opportunities to leverage institutional forces to speed up emissions reduction. These experiments allow us to explore the capacity of each modeling approach to represent insitutions and to lay out a vision for the next frontier of endogenizing institutional change in sustainability science models. To bridge the gap between modeling, theories, and empirical evidence on social institutions, this research agenda calls for joint efforts between sustainability modelers who wish to explore and incorporate institutional detail, and social scientists studying the socio-political and economic foundations for sustainability transitions.

Empirical modeling of agricultural climate risk.

Effective policies for adaptation to climate change require understanding how impacts are related to exposures and vulnerability, the dimensions of the climate system that will change most and where human impacts will be most draconian, and the institutions best suited to respond. Here, we propose a simple method for more credibly pairing empirical statistical damage estimates derived from recent weather and outcome observations with projected future climate changes and proposed responses. We first analyze agricultural production and loan repayment data from Brazil to understand vulnerability to historical variation in the more predictable components of temperature and rainfall (trend and seasonality) as well as to shocks (both local and over larger spatial scales). This decomposed weather variation over the past two decades explains over 50% of the yield variation in major Brazilian crops and, critically, can be constructed in the same way for future climate projections. Combining our estimates with bias-corrected downscaled climate simulations for Brazil, we find increased variation in yields and revenues (including more bad years and worse outcomes) and higher agricultural loan default at midcentury. Results in this context point to two particularly acute dimensions of vulnerability: Intensified seasonality and local idiosyncratic shocks both contribute to worsening outcomes, along with a reduced capacity for spatially correlated ("covariate") shocks to ameliorate these effects through prices. These findings suggest that resilience strategies should focus on institutions such as water storage, financial services, and reinsurance.

Transforming the grid for a more environmentally and socially sustainable electricity system in Great Britain is a slow and uneven process.

Electricity system decarbonization is key for environmental sustainability. From a consumption-production perspective, much attention has been paid to changes in how electricity is generated and used, but electricity systems also rely on a grid infrastructure that connects and integrates production and consumption, and which will also need to transform. At the same time, new technologies in the electricity system, including the grid, offer the potential for more socially sustainable ways of producing and consuming energy. However, in practice, change has been slow, uneven, and often dysfunctional. A socio-technical transitions approach offers insights into why this is so, seeing electricity system change not simply in technical and economic terms, but also as the outcomes of interactions between technology and social and political processes. The approach draws attention to the particular challenges of achieving rapid transitions in complex critical infrastructures like electricity with strong institutional logics of security. This article applies this approach to the case of Great Britain, where despite strong commitments to sustainability in the form of high-level climate policy, the electricity grid has often been a constraint on the pace of change. The nature of the British transition is explained partly by weak links between these high-level goals on the one hand and the detailed rules and practices in the electricity system on the other. It is also explained by patterns of ownership and grid regulation in the British case that protect incumbents and make it difficult for new actors to develop the system in more socially sustainable directions.

Naming and shaming as a strategy for enforcing the Paris Agreement: The role of political institutions and public concern.

Enforcement is a challenge for effective international cooperation. In human rights and environmental law, along with many other domains of international cooperation, "naming and shaming" is often used as an enforcement mechanism in the absence of stronger alternatives. Naming and shaming hinges on the ability to identify countries whose efforts are inadequate and effectively shame them toward better behavior. Research on this approach has struggled to identify factors that explain when it influences state behavior in ways that lead to more cooperation. Via survey of a large (N = 910) novel sample of experienced diplomats involved in the design of the Paris Agreement, we find support for the proposition that naming and shaming is most accepted and effective in influencing the behavior of countries that have high-quality political institutions, strong internal concern about climate change, and ambitious and credible international climate commitments. Naming and shaming appears less effective in other countries, so further enforcement mechanisms will be needed for truly global cooperation. We also find that the climate diplomacy experts favor a process of naming and shaming that relies on official intergovernmental actors, in contrast with studies suggesting that NGOs, media, and other private actors are more effective at naming and shaming. We suggest that these tensions-the inability for naming and shaming to work effectively within the countries least motivated for climate action and the preference for namers and shamers that seem least likely to be effective-will become central policy debates around making cooperation on climate change more enforceable.

Emergence of specialized third-party enforcement.

The question of how cooperation evolves and is maintained among nonkin is central to the biological, social, and behavioral sciences. Previous research has focused on explaining how cooperation in social dilemmas can be maintained by direct and indirect reciprocity among the participants of the social dilemma. However, in complex human societies, both modern and ancient, cooperation is frequently maintained by means of specialized third-party enforcement. We provide an evolutionary-game-theoretic model that explains how specialized third-party enforcement of cooperation (specialized reciprocity) can emerge. A population consists of producers and enforcers. First, producers engage in a joint undertaking represented by a prisoner's dilemma. They are paired randomly and receive no information about their partner's history, which precludes direct and indirect reciprocity. Then, enforcers tax producers and may punish their clients. Finally, the enforcers are randomly paired and may try to grab resources from each other. In order to sustain producer cooperation, enforcers must punish defecting producers, but punishing is costly to enforcers. We show that the threat of potential intraenforcer conflict can incentivize enforcers to engage in costly punishment of producers, provided they are sufficiently informed to maintain a reputation system. That is, the "guards" are guarded by the guards themselves. We demonstrate the key mechanisms analytically and corroborate our results with numerical simulations.