Climate change is having devastating impacts on communities’ lives, livelihoods and food security across South Asia. Its consequences are so severe that it is increasingly contributing to migration, and this incidence is likely to escalate much more in the years to come as climate change impacts become more serious. Migration has always taken place in South Asia, for long before climate change became an issue. “Push factors” include conflict, poverty, land access and ethnicity, while there are also many “pull factors” such as development, livelihoods, seasonal labour, kinship and access to health or services. However because of this background of migration, South Asian countries are slow to recognise the role of climate change as an additional push factor, and the level to which it is driving migration. Climate change is thus still largely invisible in the migration discourse in South Asia. This study looks at climate change and its impacts on migration in South Asia, and particularly in Bangladesh, India, Nepal and Sri Lanka. The South Asia region is particularly vulnerable to climate change events. Droughts, heat waves, cyclones, rising sea levels, heavy rainfall, landslides and floods strike, are often felt by two or more neighbouring countries in the region, and the Intergovernmental Panel on Climate Change Fifth Assessment Report (IPCC AR5) anticipates that these are likely to be felt more severely in future. Unfortunately, in the face of climate change, political issues governing trans-boundary rivers such as the Ganga, Brahmaputra and the Indus, creates regional tensions over who controls the water, and further exacerbates downstream communities’ vulnerability to drought or flood.