Past scientific assessments of global climate change impacts have tended to give us information on global impacts. But scientists have been refining their predictions down to regional, national and local levels. Improved understanding of climate change impacts, and particularly more specific information on which countries are most vulnerable, will affect international co-operation. Presumably, countries that are most vulnerable to climate change will be more likely to join international efforts to address climate change. At least that is what one could logically hypothesise. Questions addressed include: Does ‘vulnerability’ to climate change matter for international cooperation? What might be the political impact of improved understanding of the effects of climate change on international environmental co-operation?