Currently there are approximately 25 million people displaced by environmental conditions, including resource scarcity, natural hazards and ecosystem degradation. By 2050, as many as 200 million people are predicted to be forced from their homes by changing environmental conditions brought about or exacerbated by climate change. Yet despite the scale of this problem, there is no international policy on their status. This thesis aims, first, to investigate some of the challenges to devising international political solutions to the problem and second, investigate these challenges empirically by undertaking a comprehensive analysis of the United Nations' current approach to the problem. Drawing on political ecology, the thesis analyses debates and approaches to the problem of environmental displacement. Part 1 of the thesis investigates academic debates, particularly within International Relations. Part 2 provides a critical evaluation of how the United Nations approaches environmental displacement. Although its main agency responsible for refugees does not recognise environmentally displaced people as refugees there are nevertheless a number of United Nations' bodies concerned with this growing problem. The study argues that the United Nations' main approach, namely sustainable development, has serious limitations because it does not recognise the underlying socio-political causes of environmental displacement, including how the distribution of resources and the socio-environmental costs and benefits of development drive this phenomenon. The thesis concludes that as environmental displacement is likely to increase in the near future, a supplemental category of environmental refugee that recognises these socio-political causes is an important step to establishing coherent international responsesto the problem. In this regard,a nd despitet he political difficulties of states accepting a new refugee category, the United Nations can nevertheless play a constructive role in promoting dialogue and establishing a formal operational framework for action on environmental displacement in the international system