Built in to every multilateral environmental agreement is a dilemma: how to incorporate justiceand fairness on the one hand and effectiveness on the other. Our immense difficulty in meeting thistwo-edged imperative highlights the fact that we are, at best, at an early stage in the developmentof international environmental ethics, and that no coherent and effective ethical system yet existsin this context. This remarkable book starts from a conviction that the principle of common butdifferentiated responsibility (CBDR) offers the best way forward toward the much-desired goal ofsustainable development.