Science for International Policy on Climate Change: A Multi-Method Contribution

Abstract

Climate change is arguably the biggest policy challenge of this century, in large part because it involves complex and interdependent processes, as well as substantial physical, economic, social, and political uncertainties. This dissertation examines a series of puzzles related to international policy action on climate change, with central foci on the crucial dimensions of equity as related to human migration, and efficacy as related to governance of international environmental issues. In exploring those topics, I draw from multiple disciplines: environmental studies, economics, demography, and political science, using both quantitative and qualitative methods.In a first part, I focus on human migration and inequality in the context of climate change. First, I show that restrictive migration policy limits people’s ability to adapt to impacts from climate change. Second, I show that climate change constrains migration decisions, in particular for the poorest populations, by decreasing available resources necessary to migrate. Finally, I show that migration makes the world on average richer and more equal in all scenarios of future development described in the Shared Socioeconomic Pathways framework, a set of scenarios widely used in climate change research. To get to those results, I proceed in three integrated steps. First, I develop a framework for migration modeling compatible with existing Integrated Assessment Models (IAMs), a type of model typically used to assess damages from climate change. Second, I enrich this framework with a representation of within-region income inequality. Third, I produce socioeconomic scenarios that serve as consistent input for these modeling exercises. Evaluating relevant policy measures becomes more valuable if we know how policies are likely to be implemented in practice. Therefore, the second part of this dissertation focuses on efficacy in global governance of environmental issues. In particular, I examine the role of aspirational goals, a key feature of many environmental agreements and often the object of crucial political capital in international negotiations. Using process tracing of historical case studies, I show that such goals, in practice, have a very limited effect on policy change. This result has direct implications for the Paris Agreement and its 1.5◦C temperature target.