The thesis contains three chapters on environmental and natural resource economics and focuses on situations where agents receive private or public information. The first chapter analyses the problem of transboundary fisheries, where harvesting countries behave non-cooperatively. In addition to biological uncertainty, countries may face strategic uncertainty. A country that receives negative assessments about the current level of the fish stock, may become “pessimistic” about the assessment of the other harvesting country, which can ignite “panic-based” overfishing. In such a coordination problem, multiplicity of equilibria is a generic characteristic of the solution. Both strategic uncertainty and equilibrium selection, relatively, have been given less attention in the theoretical literature of common-property natural resources. In this model, in the limit as the harvesting countries observe more and more precise information, rationality ensures the unique “global game” equilibrium, a la Carlsson and van Damme (1993). The improved predictive power of the model helps a potential intergovernmental manager of the stock understand the threshold behaviour of harvesting countries. The global game threshold coincides with the risk-dominance threshold of a precise information model, as if there was no strategic uncertainty, and implies that the countries select the corresponding risk-dominant action for any level of assessment of the stock. Gaining from the risk-dominance equivalence, I derive policy suggestions for the overfishing cost and the property rights in common-property fisheries. The second chapter develops a theoretical framework to examine the role of public information in dynamic self-enforcing international environmental agreements (IEAs) on climate change. The countries choose self-enforcing emission abatement strategies in an infinite-horizon repeated game. In a stochastic model, where the social cost of greenhouse gasses (GHG) is a random variable, a central authority, as an information sender, can control release of information about the unknown state to the countries. In the literature on stochastic IEAs, it is shown that comparison of different scenarios of learning by the countries, depends on ex-ante difference of true social cost of GHG from the prior belief of countries. Here, I try to understand, in a signalling game between the informed sender and the countries, whether the no-learning or imperfect-learning scenarios, can be an equilibrium outcome. It is shown that the equilibrium strategy of the sender, who is constrained to a specific randomisation device and tries to induce an incentive-compatible abatement level which is Pareto superior, leads to full learning of social cost of GHG of symmetric and asymmetric countries. Finally, in the third chapter, I again examine a setting, where a central authority, as an information sender, conducts research on the true social cost of climate change, and releases information to the countries. However, in this chapter, instead of restricting the sender to a specific signalling structure, the sender, who has commitment power, by designing an information mechanism (a set of signals and a probability distribution over them), maximises his payoff, which depends on the mitigation action of countries and the social cost of green-house gases(GHG). The countries, given the information policy (the probability distribution over signals) and the public signal, update their beliefs about the social cost of GHG and take a mitigation action. I derive the optimal information mechanism from the general set of public information mechanisms, in coalition formation games. I show that the coalition size, as a function of beliefs, is an endogenous variable, induced by the information sender. If the sender maximises the expected payoff of either of non-signatories or signatories of the climate treaty, then full revelation is the optimal information policy, while if the sender attempts to reduce the global level of GHG, then optimal information policy leads to imperfect disclosure of the social cost. Furthermore, given any of the specifications of the sender’s payoff, the optimal information policy leads to the socially optimal mitigation and membership outcomes.

Cette thèse est une contribution à la théorie économique sur trois aspects: la dynamique de prix dans les marchés financiers avec asymétrie d’information, la mise à jour des croyances et les raffinements d'équilibre dans les jeux de signaux, et l'introduction de l'ambiguïté dans la théorie du prix limite. Dans le chapitre 2, nous formalisons un jeu d'échange à somme nulle entre un secteur mieux informé et un autre qui l'est moins, pour déterminer de façon endogène, la dynamique du prix sous-jacent. Dans ce modèle, joueur 1 est informé de la conjoncture (L) mais est incertain de la croyance de joueur 2, car ce dernier est seulement informé à travers un message (M) qui est lié à cette conjoncture. Si L et M sont indépendants, alors le processus de prix sera une Martingale Continue à Variation Maximale (CMMV) et joueur 1 peut disposer de cet avantage informationnel. Par contre, si L et M ne sont pas indépendants, joueur 1 ne révèlera pas son information pendant le processus, et il ne bénéficiera donc pas de son avantage en matière d'information. Dans le chapitre 3, je propose une définition de l'équilibre de Test d'hypothèse (HTE) pour des jeux de signaux généraux, avec des joueurs non-Bayésiens qui sont soumis à une règle de mise à jour selon le modèle de vérification d'hypothèse caractérisé par Ortoleva (2012). Un HTE peut être différent d'un équilibre séquentiel de Nash en raison d'une incohérence dynamique. Par contre, dans le cas où joueur 2 traite seulement un message à probabilité nulle comme nouvelle inespérée, un HTE est un raffinement d'équilibre séquentiel de Nash et survit au critère intuitif dans les jeux de signaux généraux mais pas inversement. Nous fournissons un théorème d'existence qui couvre une vaste classe de jeux de signaux qui sont souvent étudiés en économie. Dans le chapitre 4, j'introduis l’ambiguïté dans un modèle d'organisation industrielle classique, dans lequel l'entreprise déjà établie est soit informée de la vraie nature de la demande agrégée, soit soumise à une incertitude mesurable classique sur la conjoncture, tandis qu'un éventuel nouvel arrivant fait face à une incertitude a la Knight (ambiguïté) concernant cette conjoncture. Je caractérise les conditions sou lesquelles le prix limite émerge en équilibre, et par conséquent l'ambigüité diminue la probabilité d'entrée. L'analyse du bien-être montre que le prix limite est plus nocif dans un marché où la demande escomptée est plus élevée que dans un autre où celle-ci est moindre. / This thesis contributes to the economic theory literature in three aspects: price dynamics in financial markets with asymmetric information belief updating and equilibrium refinements in signaling games, and introducing ambiguity in limit pricing theory. In chapter 2, we formulate a zero-sum trading game between a better informed sector and a less 1nformed sector to endogenously determine the underlying price dynamics. In this model, player 1 is informed of the state (L) but is uncertain about player 2's belief about the state, because player 2 is informed through some message (M) related to the state. If L and M are independent, then the price proces s will be a Continuous Martingale of Maximal Variation (CMMV), and player 1 can benefit from his informational advantage. However, if L and M are not independent, player 1 will not reveal his information during the trading process, therefore, he does not benefit from his informational advantage. In chapter 3, I propose a definition of Hypothesis Testing Equilibrium (HTE) for general signaling games with non-Bayesian players nested, by an updating rule according to the Hypothesis Testing model characterized by Ortoleva (2012). An HTE may differ from a sequential Nash equilibrium because of dynamic inconsistency. However, in the case in which player 2 only treats a zero-probability message as an unexpected news, an HTE is a refinement of sequential Nash equilibrium and survives the intuitive Critenon in general signaling games but not vice versa. We provide an existence theorem covering a broad class of signaling games often studied in economics. In chapter 4, I introduce ambiguity in a standard industry organization model, in which the established firm is either informed of the true state of aggregate demand or is under classical measurable uncertainty about the state, while the potential entrant is under Knightian uncertainty (ambiguity) about the state. I characterize the conditions under which limit pricing emerges in equilibria, and thus ambiguity decreases the probability of entry. Welfare analysis shows that limit pricing is more harmful in a market with higher expected demand than in a market with lower expected demand.