This paper critically examines the perceived threat of ‘climate refugees’ and ‘climate conflict’. It locates the ideological roots of these concepts in development theories and policy narratives about demographically induced migration, environmental refugees and environmental security. While alarmist rhetoric around climate refugees and conflict has been deployed by a variety of actors, including U.N. agencies, development NGOs, national governments, security pundits and popular media, the paper concentrates on its strategic use by U.S. defence interests. It raises the question of how the portrayal of climate change as a security threat could further militarise the provision of development assistance and distort climate policy. Copyright © 2010 John Wiley & Sons, Ltd.