Existing empirical models of international co-operation emphasize domestic determinants, although virtually all theories of international relations focus on interdependencies between countries. This article examines how much states' linkages with the international system, relative to domestic factors, such as income and democracy, influence the dynamics of global governance efforts. To this end, we study the ratification behaviour of 180 countries vis-a`-vis 255 global environmental treaties. Except for integration into the world economy, which affects co-operative behaviour negatively, our results show that international factors have a stronger and more positive impact on cooperative behaviour than domestic factors. This implies that Galton's advice not to examine the effects of internal and external variables in isolation is also useful in the study of international politics.

This article reviews the existing theoretical arguments and empirical findings linking renewable and non-renewable natural resources to the onset, intensity, and duration of intrastate as well as interstate armed conflict. Renewable resources are supposedly connected to conflict via scarcity, while non-renewable resources are hypothesized to lead to conflict via resource abundance. Based upon our analysis of these two streams in the literature, it turns out that the empirical support for the resource scarcity argument is rather weak. However, the authors obtain some evidence that resource abundance is likely to be associated with conflict. The article concludes that further research should generate improved data on low-intensity forms of conflict as well as resource scarcity and abundance at subnational and international levels, and use more homogenous empirical designs to analyze these data. Such analyses should pay particular attention to interactive effects and endogeneity issues in the resource–conflict relationship.

Despite many claims by high-ranking policymakers and some scientists that climate change breeds violent conflict, the existing empirical literature has so far not been able to identify a systematic, causal relationship of this kind. This may either reflect de facto absence of such a relationship, or it may be the consequence of theoretical and methodological limitations of existing work. In this article we revisit the climate–conflict hypothesis along two lines. First, we concentrate on indirect effects of climatic conditions on conflict, whereas most of the existing literature focuses on direct effects. Specifically, we examine the causal pathway linking climatic conditions to economic growth and to armed conflict, and argue that the growth–conflict part of this pathway is contingent on the political system. Second, we employ a measure of climatic variability that has advantages over those used in the existing literature because it can presumably take into account the adaptation of production to persistent climatic changes. For the empirical analysis we use a global dataset for 1980–2004 and design the testing strategy tightly in line with our theory. Our empirical analysis does not produce evidence for the claim that climate variability affects economic growth. However, we find some, albeit weak, support for the hypothesis that non-democratic countries are more likely to experience civil conflict when economic conditions deteriorate.

Environmental factors are likely to affect human mobility in the form of migration, but the empirical evidence remains to be inconclusive. This research seeks to contribute shedding more light on this ambiguity: we examine whether and how environmental change leads to internal (i.e., domestic) migration at the individual level. It is argued that individual perceptions of different types of environmental change (sudden vs. gradual events) determine migration decisions in diverse ways. Empirically, the corresponding arguments are analyzed with new survey data, which have been collected in five developing countries and include both individuals who migrated and those who decided to stay. The results suggest that individual perceptions of long-term (gradual) environmental events, such as droughts, lower the likelihood of internal migration. However, there is some evidence that sudden-onset events, such as floods, increase the chances to move. These findings substantially improve our understanding of which type of environmental factors make individuals leave their homes, and they suggest that a more differentiated perspective on the issue of environmental migration based on adaptation is needed.

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