Climate change, framed in social scientific terms, offers a causal and moral narrative which connects, for example, users of electric toothbrushes in the USA and couples quarrelling about habits of consumption in Europe and Japan, with representatives disputing about a post-Kyoto agreement at global climate conferences, all the way to victims of flooding and draught events in Australia, China, India and Bangladesh. Even climate sceptics react to and thereby affirm the dominance of such a climate narrative. This coercive inclusion of the excluded ‘distant other’ is what I define as the social scientific fact of ‘cosmopolitization’ – in distinction from ‘cosmopolitanism’ as a philosophical norm.By taking climate change as a comprehensive case study experiment, this research project aims at reinventing the social sciences for the ‘age of cosmopolitization’. The ground-breaking nature of the project is to advance the present state of debate by validating the new theoretical, methodological and empirical tools needed for such a ‘cosmopolitan turn’.Since their inception in the late 19th century, the social sciences remain caught in a resilient methodological nationalism bound up with the presupposition that the national-territorial remains the primary container for the analysis of social, economic, political and cultural processes. Methodological nationalism is built into the basic concepts of modern sociology and political science, as well as into routines of data collection and analysis. Building on my previous work on methodological cosmopolitanism, this project undertakes a full-scale cosmopolitan case study of climate change, thereby rendering operative a new mode of transnational research cooperation, data generation, and theory validation.