Clark Gray

Climate change is likely to affect human migration, but this will occur via trapping potential migrants as well as displacing them. Sea level rise, climate-related disasters and heatwaves will clearly compel some people to move as climate change unfolds, but we cannot assume that the most vulnerable will be able to move.

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Among the greatest social concerns associated with climate change is involuntary human displacement and migration. The public discussion on this topic has been dominated by the spectre of “climate refugees” permanently displaced over long distances and towards high-income countries. However a growing body of demographic and statistical research has begun to evaluate this narrative and has largely rejected it for a more nuanced view.

In our recent paper, we use a new, large-sample data source on internal and international migration from five African countries (Kenya, Uganda, Nigeria, Burkina Faso and Senegal) which we link to high-resolution data on climate change. We then test how temperature and rainfall affect the departure of internal and international migrants while accounting for non-climatic influences on migration. Using this approach, we find that that climatic influences on migration vary distinctly from country to country, reflecting large social and environmental differences between the countries we studied. Only in Uganda do we find the expected relationship where migration increases with temperature, consistent with a “climate refugees” framing. In Senegal and Nigeria we find no consistent climate effects.

In Kenya and Burkina Faso, migration declines with temperature, suggesting a “trapped populations” dynamic in which households retain potential migrants during periods of climate stress. The latter finding is consistent with the high financial and social barriers to long-distance migration in these contexts.

These results challenge common assumptions about climate migration but are consistent with previous research. Recent studies using similar approaches have found that temperature reduces migration in Indonesia, Tanzania, and Bolivia while increasing it in the Philippines, Pakistan, South Africa, Mexico and Brazil. These differences may partly reflect methodological differences between studies, a possibility that we are currently exploring by looking for within-country differences across time and space. However we believe that these results also reflect real differences in the direction of climate-migration relationships, a finding which greatly complicates general narratives of climate-induced displacement.

The takeaway from these studies is that climate change is likely to affect human migration, but this will occur via trapping potential migrants as well as displacing them. Sea level rise, climate-related disasters and heatwaves will clearly compel some people to move as climate change unfolds, but we cannot assume that the most vulnerable will be able to move, nor that those who move will do so permanently or over long distances. These results support broad, climate-linked social protection policies such as crop insurance: If effective, these policies will help to prevent involuntary displacement while also enabling adaptive migration which would otherwise have been prevented.


Clark Gray is Assistant Professor of Geography at the University of North Carolina in Chapel Hill. His research uses demographic and statistical techniques to investigate human-environment relationships at regional to global scales.

This blog is based on the paper: Country-specific effects of climate variability on human migration.


Images: CAIT / Neil Palmer – (CC BY-SA 2.0) from Flickr.

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