A new report says climate change may cause vast human migrations on an order not previously experienced. The report, In Search of Shelter: Mapping the Effects of Climate Change on Displacement and Migration, was written by researchers at CIESIN, the United Nations University, and CARE International. Drawing on empirical evidence from a new survey of every continent, with original maps created by CIESIN that pinpoint potential locations of critical displacements, the report explores how climate change is already causing people to leave their homes, and details some of the specific ways displacement may occur over the next decades. For example, the report says, melting glaciers will negatively affect agricultural systems throughout Asia and contribute to the risk of flooding. Natural disasters will continue to cause short-term migration, while the breakdown of eco-system-dependent livelihoods—such as subsistence herding, farming, and fishing—will cause long-term migration. Developing countries will be most vulnerable to migration and displacement, with less capacity to implement adaptation measures.

A potential downward spiral from resulting ecological degradation and breakdown of social structures could ensue, leading to political instability which would further exacerbate population displacement. The report calls for seeing climate-related migration and displacement as global in nature, not simply isolated local crises. It aims to inform critical policy making by presenting a comprehensive discussion of the linkages between environmental change, displacement, and migration.