Drought and aridity influence internal migration worldwide

While the effects of climatic changes on migration have received widespread public and scientific attention, comparative evidence for their influence on internal migration worldwide remains scarce. Here we use census-based data from 72 countries (1960–2016) to analyse 107,840 migration flows between subnational regions. We find that increased drought and aridity have a significant impact on internal migration, particularly in the hyper-arid and arid areas of Southern Europe, South Asia, Africa and the Middle East and South America. Migration patterns are shaped by the wealth, agricultural dependency and urbanization of both origin and destination areas with migration responses being stronger in rural and predominantly agricultural areas. While overall climatic effects on migration are stronger in richer countries, we observe higher out-migration from poorer towards wealthier regions within countries. Furthermore, age and education groups respond differently to climatic stress, highlighting distinct mobility patterns of population subgroups across different geographic contexts. Limited comparative evidence exists on the impacts of climatic factors on internal migration. Here, using a harmonized census-based dataset, the authors find that drought and aridity substantially increase internal migration, with considerable heterogeneity across regions, age groups and education levels.