Over the past decade human understanding of the potential variety and range of climate change impacts has expanded. For example, besides physical and environmental impacts it is clear that climate change is a driver of social change. This is particularly apparent through the creation of a new social community of “climate migrants”. In 1995 there were about 25 million environmental refugees around the world but this number is anticipated to rise to 200 million by 2050, many of them as a result of climate change. One of the countries most severely affected by climate induced migration is Bangladesh. This paper analyses how consideration of this growing body of climate migrants fits with traditional migration theory. Using a case study approach drawing on empirical research amongst migrants in Bangladesh, it examines the drivers of migration, the impacts on individual and family livelihoods of the explosion of climate migrants and the subsequent effects on urbanisation of major cities in Bangladesh.