Abstract
Involuntary human migration is among the social outcomes of greatest concern in the current era of global climate change. Responding to this concern, a growing number of studies have investigated the consequences of short to medium-term climate variability for human migration using demographic and econometric approaches. These studies have provided important insights, but at the same time have been significantly limited by lack of expertise in the use of climate data, access to cross-national data on migration, and attention to model specification. To address these limitations, we link data on internal and international migration over a 6-year period from 9812 origin households in Kenya, Uganda, Nigeria, Burkina Faso and Senegal to high-resolution gridded climate data from both station and satellite sources. Analyses of these data using several plausible specifications reveal that climate variability has country-specific effects on migration: Migration tends to increase with temperature anomalies in Uganda, tends to decrease with temperature anomalies in Kenya and Burkina Faso, and shows no consistent relationship with temperature in Nigeria and Senegal. Consistent with previous studies, precipitation shows weak and inconsistent relationships with migration across countries. These results challenge generalizing narratives that foresee a consistent migratory response to climate change across the globe.
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Notes
To address the small number of spatial units in Burkina Faso we conducted a simulation in which one unit was removed at a time from Specification A. In these 10 simulations, the raw temperature coefficient remained highly significant in all cases and increased or decreased by a maximum of 11 %. The precipitation coefficient remained non-significant in all cases.
These models are estimated as Poisson rather than negative binomial because the POSTRCSPLINE package in Stata is available only for the former (Buis 2009).
Thus relative to Specification A this model has three additional terms: temperature squared, precipitation squared and temperature times precipitation.
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Acknowledgments
The authors are grateful for assistance and constructive comments from M. Gutmann and A. Henley. The participation of C.G. was supported by the National Institutes of Health (R00HD061752).
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Gray, C., Wise, E. Country-specific effects of climate variability on human migration. Climatic Change 135, 555–568 (2016). https://doi.org/10.1007/s10584-015-1592-y
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DOI: https://doi.org/10.1007/s10584-015-1592-y