Suchergebnisse

Internationale Umweltabkommen wurden und werden verhandelt, um fortschreitenden Klimawandel zu begrenzen. Kooperation ist erforderlich, da durch die Reduzierung von Treibhausgasemissionen ein globales öffentliches Gut bereitgestellt wird und steigende Temperaturen nur durch globale Anstrengungen vermieden werden können. Allerdings erschweren Trittbrettfahreranreize freiwillige Emissionsreduktionen von souveränen Staaten. Die vorliegende Arbeit befasst sich mit der Frage, wie Kooperation beim Klimaschutz unter verschiedenen Gestaltungen eines internationalen Vertrages trotz Trittbrettfahreranreizen zustande kommen kann. Die Arbeit verwendet integrierte Bewertungsmodelle, um regionale Kosten und Nutzen von Emissionsvermeidung zu quantifizieren, und identifiziert Regionen, die von internationaler Kooperation profitieren, sowie potentielle Verlierer. Die numerischen Modelle zeigen, dass Transferzahlungen zwischen Ländern Kooperation fördern könnten, sodass die Lücke bzgl. globaler Wohlfahrt zwischen voller Kooperation und Abwesenheit von Kooperation etwa zur Hälfte geschlossen werden könnte. Die Höhe der erforderlichen Zahlungen ist dabei vergleichsweise moderat, was aus Modellannahmen bzgl. der Kosten und des Nutzens von Vermeidung folgt. Anschließend untersucht die Arbeit die Implementierung der finanziellen Leistungen. Mögliche negative Konzequenzen der Transferzahlungen werden identifiziert, die das Potential haben, Kooperation zu erschweren. Moderate Zahlungshöhen erweisen sich auch hier als vorteilhaft, indem sie die potentiellen negativen Effekte für Empfängerländer begrenzen, die besonders bei Transferleistungen, die auf Gerechtigkeitsmotiven beruhen, wichtig werden. Die Festlegung von moderateren Zielen könnte auch in Bezug auf zwei andere Elemente eines Vertrages förderlich für Kooperation sein: (i) die Einbeziehung von unbegrenztem Emissionshandel mit Ländern ohne Reduktionsziele und (ii) die Festschreibung von Vermeidungszielen durch feste Emissionsreduktionen. Die Arbeit zeigt, dass beide Gestaltungen eines internationalen Klimavertrages dazu führen, dass die Koalition für zusätzliche Wohlfahrtssteigerungen zahlt. Obwohl die globale Wohlfahrt zunimmt, werden Trittbrettfahreranreize größer. Demnach reduziert ein Vertrag, der (i) die Menge an Zertifikaten im Emissionshandel begrenzt oder (ii) die Implementierung einer Emissionssteuer vorsieht, Trittbrettfahreranreize. Die Arbeit zeigt, dass sowohl Abkommen mit ambitionierten oder mit moderaten Zielen zu höherer globaler Wohlfahrt führen können, abhängig von Parameterwerten in den Modellen. ; International environmental agreements have been and are negotiated to facilitate mitigation efforts on climate change. To avoid severe impacts, global cooperation is required as the reduction of greenhouse gas emissions represents a global public good. However, free-riding incentives impede the voluntary contribution of abatement by sovereign countries. The present thesis studies how climate cooperation could advance under different treaty designs in the face of free-riding incentives. The thesis uses integrated assessment models to quantify regional differences with respect to costs and benefits from mitigating climate change and identifies regions that gain from cooperation as well as potential losers. Within the numerical models, transfers are found to enhance cooperation such that stable agreements could close the gap between full cooperation and no cooperation roughly half with respect to global welfare. The magnitudes of transfer payments show comparably moderate magnitudes resulting from modeling assumptions on costs and benefits of mitigation. Following this assessment, the thesis studies the implementation of payments. Adverse effects of transfers are identified which have the potential to impede cooperation on climate change. Moderate magnitudes of transfers are found to be of advantage by limiting the potential adverse effects on recipient countries, for which negative consequences could especially be relevant when transfers are based on equity considerations. Defining the obligations of a treaty in a more moderate way might enhance cooperation also with respect to two other design options: (i) including unrestricted emissions trading with countries that do not have abatement targets and (ii) formulating the obligations of a treaty in emission assignments. The thesis finds that both treaty design options imply additional welfare gains for which the coalition pays and that no country can be excluded from. While global welfare is enhanced, free-riding is likely to become more attractive. In turn, (i) restricting the amount of emission permits in the market for the coalition or (ii) basing a treaty on emission taxes may enhance the participation in the agreement because welfare gains for free-riders are reduced. However, the thesis finds that both agreements under ambitious or moderate obligations could be more successful with respect to global welfare depending on modeling parameters.

We consider a standard optimal taxation framework in which consumers' preferences are separable in consumption and labor and identical over consumption, but are affected by consumption externalities. For every nonlinear, income-dependent pricing of goods there is a linear pricing scheme, combined with an adjusted income tax schedule, that leaves all consumers equally well-off and weakly increases the government's budget. The result depends on whether a linear pricing scheme exists that keeps the aggregate amount of consumption at its initial level observed under nonlinear pricing. We provide sufficient conditions for the assumption to hold. If adjusting the income tax rate is not available, personalized prices for an externality can enhance social welfare if they are redistributive, that is, favor consumers with a larger marginal social value of income.

The social cost of carbon is the central economic measure for aggregate climate change damages and functions as a metric for optimal carbon prices. Previous literature shows that inequality significantly influences the level of the social cost of carbon, but mostly neglects a major source of inequality - heterogeneity in income below the national level. We characterize the relationship between climate and redistributional policy in an optimal taxation model that explicitly accounts for inequality between and within countries. In particular, we demonstrate that climate and distributional policy cannot be separated when national governments fail to compensate low-income households for climate change damages: Even if only one country does not compensate especially affected households, the social cost of carbon increases globally. Further, we use numerical methods to estimate the scope of these effects. Our results suggest that it is crucial to correct previous estimates of the social cost of carbon for national distributional policies.

We investigate how different designs of carbon offset mechanisms, like theKyotoProtocol'sCleanDevelopmentMechanism (CDM), affect the success of self‐enforcing climate treaties. In a game‐theoretic numerical model of coalition formation we find that participation in the agreement is negatively affected when strategic behavior and free‐rider incentives matter. This does not change when selling targets restrict credit supply. Substantially higher participation emerges when the treaty restricts its signatories not to use the gains from credit trading to lower their emission caps. Despite the high sensitivity of participation to differentCDMdesign, we find that global welfare levels achieved in various equilibria are remarkably similar.