Jean-Christophe Pereau

Sustainable coalitions in the commons

It is well known that the lack of cooperation among agents harvesting a renewable resource is critical for its sustainable management. The present paper gives insights into the complex balance between coalition structures, resource states or dynamics and the agent heterogeneity necessary to avoid bio-economic collapses. A model bringing together coalition games and a viability approach is proposed to focus on the compatibility between bio-economic constraints and exploited common stock dynamics. The extent to which cooperation promotes sustainability is examined. Our results suggest that the stability of the grand coalition occurs for large enough stocks. By contrast, for lower levels of resources, the most efficient user plays the role of veto player.

A bio-economic model for the ecosystem-based management of the coastal fishery in French Guiana

This paper offers a theoretical and empirical modeling for ecosystem-based fishery management (EBFM). A multi-species and multi-fleets model integrating Lokta-Volterra trophic dynamics and profit functions is developed for the coastal fishery of French Guiana. This small-case fishery constitutes a challenging example with high fish biodiversity, several non selective fleets and a potentially increasing local food demand due to demographic pressure. The dynamic model is calibrated with thirteen species and four fleets using catch and effort data on a monthly basis from 2006 to 2009. Several contrasting fishing scenarios including status quo, total closure, economic and viable strategies are simulated and compared from both biodiversity preservation and socio-economic performance viewpoints. We show that fishing outputs including food supply and profitability of fleets can be sustained although a significant loss of biodiversity cannot be avoided.

Ecological-economic modelling for the sustainable management of biodiversity

Terrestrial and marine biodiversity provides the basis for both ecosystems functioning and numerous commodities or services that underpin human well-being. From several decades, alarming trends have been reported worldwide for both biodiversity and ecosystem services. Therefore the sustainable management of biodiversity requires a double viewpoint balancing ecological conservation with the welfare of human societies. Understanding the underlying trade-offs, synergies and interactions imposes the development of interdisciplinary researches and methods. In that respect, bio-economic or ecological economic modeling is likely to play a major role. The present paper intends to elicit the key features, strengths and challenges of bio-economic approaches especially in mathematical and computational terms. It first recall the main bio-economic methods, models and decisional instruments used in these types of analyses. Then the paper shows to what extent bio-economic sustainability lies between equilibrium, viability and optimality mathematical frameworks. It ends up by identifying new major challenges among which the operationalization of ecosystem based management, the precautionary principle and the implementation of governance are especially important.

Co-operation and Unilateral Commitment in the Presence of Global Environmental Problems

This paper focuses on the link between group co-operation and unilateral commitment of some countries in the presence of global environmental problems. We show that in case of a failure of negotiation, some countries can decide to commit unilaterally and reduce their emissions. We call this behaviour precautionary commitment. Absence of international agreement does not mean global defection from the environmental issue.We also show that the emergence of a non-co-ordinatedglobal co-operation can result from a strategic actionfrom the members of the coalition. The insiders of the coalition create an incentive for the non-members to reduce without co-ordinating their emissions.

Forming coalitions to negotiate North–South climate agreements

This paper analyzes North-South negotiations over climate change abatement. We consider that northern countries have an incentive to negotiate over a transfer to the southern countries in exchange for their abatement efforts rather than reducing their emissions at home. We study the incentives for northern and southern countries to form negotiation-coalitions at each side of the bargaining table and the impact of these negotiation-coalitions on the final outcome. We show that the incentives can be separated into direct efficiency gains, as fixed costs savings, and indirect bargaining power gains. Depending on the relative values of these gains, we determine the equilibrium of the game. We also show that bargaining power gains encourage southern countries to negotiate separately while they encourage northern countries to unite, and that this hinders the formation of the grand coalition.

An Evolutionary Approach to the Climate Change Negotiation Game

We describe in this paper an evolutionary game theoretic model aiming at representing the climate change negotiation. The model is used to examine the outcome of climate change negotiations in a framework which seeks to closely represent negotiation patterns. Evolutionary setting allows us to consider a decision making structure characterised by agents with bounded knowledge practising mimics and learning from past events and strategies. We show on that framework that a third significant alternative to the binary coordination-defection strategies needs to be considered: a unilateral commitment as precautionary strategy. As a means to widen cooperation, we examine the influence of linking environmental and trade policies via the implementation of a trade penalty on non cooperative behaviours.

Staggered Wage Setting in Normal and Real Terms: A Comparative Analysis*

This paper analyses the behaviour of an economy characterized by staggered wage contract rules specified in nominal and in real terms. It is shown that staggered contracts in real terms imply complex eigenvalues which cause oscillatory paths both for output and unemployment and stronger output losses in response to an unexpected and permanent fall in the growth rate of money supply. Copyright 2001 by Blackwell Publishing Ltd and the Board of Trustees of the Bulletin of Economic Research

The Tragedy of Open Ecosystems

This paper investigates the role played by cooperation for the sustainable harvesting of an ecosystem. To achieve this, a bio-economic model based on a multi-species dynamics with interspecific relationships and multi-agent catches is considered. A comparison between the non-cooperative and cooperative optimal strategies is carried out. Revisiting the Tragedy of Open Access and over-exploitation issues, it is first proved analytically how harvesting pressure is larger in the non-cooperative case for every species. Then it is examined to what extent gains from cooperation can also be derived for the state of the ecosystem. It turns out that cooperation clearly promotes the conservation of every species when the number of agents is high. When the number of agents remains limited, results are more complicated, especially if a species-by-species viewpoint is adopted. However, we identify two metrics involving the state of every species and accounting for their ecological interactions which exhibit gains from cooperation at the ecosystem scale in the general case. Numerical examples illustrate the mathematical findings.

Application of periodic autoregressive process to the modeling of the Garonne river flows

Accurate forecasting of river flows is one of the most important applications in hydrology, especially for the management of reservoir systems. To capture the seasonal variations in river flow statistics, this paper develops a robust modeling approach to identify and to estimate periodic autoregressive (PAR) model in the presence of additive outliers. Since the least squares estimators are not robust in the presence of outliers, we suggest a robust estimation based on residual autocovariances. A genetic algorithm with Bayes information criterion is used to identify the optimal PAR model. The method is applied to average monthly and quarter-monthly flow data (1959–2010) for the Garonne river in the southwest of France. Results show that the accuracy of forecasts is improved in the robust model with respect to the unrobust model for the quarter-monthly flows. By reducing the number of parameters to be estimated, the principle of parsimony favors the choice of the robust approach.

Environmental flows in hydro-economic models

The protection of environmental flows, as a management objective for a regulating agency, needs to be consistent with the aquifer water balance and the degree of resource renewability. A stylized hydro-economic model is used where natural recharge, which sustains environmental flows, is considered both in the aquifer water budget and in the welfare function as ecosystem damage. Groundwater recharge and the associated natural drainage may be neglected for aquifers containing fossil water, where the groundwater is mined. However, when dealing with an aquifer that constitutes a renewable resource, for which recharge is not negligible, natural drainage should explicitly appear in the water budget. In doing so, the optimum path of net extraction rate does not necessarily converge to the recharge rate, but depends on the costs associated with ecosystem damages. The optimal paths and equilibrium values for the water volume and water extraction are analytically derived, and numerical simulations based on the Western La Mancha aquifer (southwest Spain) illustrate the theoretical results of the study.RésuméL’objectif de préservation des flux environnemetaux par une agence de régulation doit être compatible avec le bilan hydrique de l’aquifère et son degré de renouvelabilité. Un modèle hydro-économique stylisé est. développé dans lequel le drainage naturel qui assure le maintien de ces flux environnementaux, apparaît à la fois dans le bilan hydrique de l’aquifère et comme dommage pour les écosystèmes dans la fonction objective de l’agence de régulation. La recharge de l’aquifère et le drainage naturel peuvent être considérés comme négligeable pour des aquifères dont la resource est. épuisable. Cependant, quand l’aquifère est. une resource renouvelable avec une recharge naturelle non négligeable, le drainage naturel doit explicitement apparaître dans le bilan hydrique de l’aquifère. Il en résulte que la trajectoire optimale du taux net de prélèvement ne converge pas nécessairement vers le taux de recharge naturel et va dépendre des coûts associés aux dommages environnementaux. Les expressions analytiques des trajectoires optimales et des valeurs d’équilibre de long terme du volume d’eau et du montant d’extraction sont calculées. Des simulations numériques réalisées sur l’Aquifère Ouest La Mancha (Sud-ouest de l’Espagne) illustrent les résultats théoriques de cette étude.ResumenLa protección de los caudales ambientales, como un objetivo de gestión para una agencia reguladora, debe ser coherente con el equilibrio hídrico del acuífero y el grado de renovabilidad de los recursos. Se utiliza un modelo hidroeconómico estilizado donde la descarga natural, que sustenta los flujos ambientales, se considera tanto en el balance de agua del acuífero como en la función de beneficios como de perjuicios para al ecosistema. La recarga de agua subterránea y el drenaje natural asociado pueden descuidarse para los acuíferos que contienen agua fósil, donde se extrae el agua subterránea. Sin embargo, cuando se trata de un acuífero que constituye un recurso renovable, para el cual la recarga no es insignificante, el drenaje natural debe aparecer explícitamente en el balance de agua. Al hacerlo, la ruta óptima de la tasa de extracción neta no necesariamente converge a la tasa de recarga, sino que depende de los costos asociados con los daños del ecosistema. Los caminos óptimos y los valores de equilibrio para el volumen de agua y la extracción de agua se derivan analíticamente, y las simulaciones numéricas basadas en el acuífero occidental de La Mancha (suroeste de España) ilustran los resultados teóricos del estudio.摘要作为管理机构的一项管理目标,环境水流的保护需要与含水层水平衡及资源可再生性程度保持一致。在维持环境水流的天然排泄被认为在含水层水平衡和福利功能中作为生态损害因素的地方采用了程式化的水经济模型。地下水补给以及相关的天然排水对于含有原生水的含水层来说可以忽略。然而,在处理构成可再生资源的、补给不可忽略的含水层时,天然排水应当明确地出现在水平衡中。为此,纯抽水量的最佳途径没有必要汇聚至补给量上,但取决于与生态损害的成本。水量及抽水量最忌途径和平衡值通过解析获得,基于(西班牙西南部)La Mancha西部含水层的数值模拟描述了研究的理论结果。ResumoA proteção de fluxos ambientais, como um objetivo de gestão para uma agencia reguladora, precisa ser consistente com o balanço hídrico do aquífero e o grau de renovação do recurso. Um modelo hidroeconômico estilizado é usado onde a descarga natural, que sustenta os fluxos ambientais, é considerada tanto no balanço hídrico do aquífero e na função de bem-estar como em danos ao ecossistema. A recarga das águas subterrâneas e a drenagem natural associada podem ser negligenciadas para aquíferos contendo água fóssil, onde as águas subterrâneas são explotadas. No entanto, ao lidar com um aquífero que constitui um recurso renovável, para o qual a recarga não é negligenciável, a drenagem natural deve aparecer explicitamente no balanço hídrico. Ao fazê-lo, o caminho ideal da taxa de extração liquida não converge necessariamente para a taxa de recarga, mas depende dos custos associados aos danos do ecossistema. Os caminhos ideais e os valores de equilíbrio para o volume de água e a extração de água são derivados analiticamente, e as simulações numéricas baseadas no aquífero La Mancha ocidental (sudoeste da Espanha) ilustram os resultados teóricos do estudo.