The Increase in Drought is Driving Internal Migrations Worldwide

The increase in heat waves and periods of drought due to climate change is driving millions of people to leave their homes and move elsewhere. In many cases, however, these migration movements occur between regions within the same country and often go unnoticed.

To quantify and track this phenomenon, an international group of scholars has, for the first time, compiled data on internal migrations that occurred in 72 countries between 1960 and 2016. The results – published in Nature Climate Change  – show how the increase in drought fosters depopulation in affected regions, especially in areas with a high prevalence of agriculture.

“The rise in drought has a significant impact on internal migrations, particularly in arid regions of Southern Europe, South Asia, Africa, the Middle East, and South America,” explains Raya Muttarak, a professor at the Department of Statistical Sciences "Paolo Fortunati" at the University of Bologna, and one of the authors of the study. “These migration phenomena are influenced by the wealth level, dependence on agriculture, and the degree of urbanisation of both the origin and destination areas: in particular, rural and agricultural regions are the most affected by depopulation.”

Many regions worldwide are facing extended droughts and increasing aridification, driven by rising temperatures and shifts in precipitation patterns. According to the World Bank, these phenomena could force up to 216 million people to leave their homes and migrate to other regions within their country by 2050.

These migration movements are already occurring but have received little attention so far. To investigate them further, researchers have analysed data from 201 censuses in 72 countries between 1960 and 2016. By analysing 107,840 migration movements across the 1,410 administrative regions considered, the researchers have created, for the first time, a global database of internal migrations.

The data clearly show that migration increases with rising levels of aridity: climatic pressure pushes populations to a point where leaving their homes becomes the only viable solution. This migration drive primarily affects younger people, particularly those between the ages of 21 and 30, predominantly male and with a medium-to-high level of education.

“As the effects of climate change continue to unfold before our eyes, predictive models suggest that the frequency and intensity of drought periods will continue to increase in various regions of the planet,” adds Muttarak. “Water scarcity and difficulties in managing agricultural land will become increasingly severe in these areas, forcing populations to seek better living conditions elsewhere.”

Based on these scenarios, the researchers suggest that it is crucial to create migration corridors, offering adequate structures and infrastructure to support the movement of people, as well as social and healthcare services capable of managing the needs of rapidly growing urban populations.

“Policies are needed to promote the diversification of economic activities, particularly in regions heavily reliant on agriculture, and social support networks that can mitigate forced migration,” confirms Muttarak. “Only in this way will it be possible to protect populations and foster resilience in communities affected by drought and aridification.”

The study was published in Nature Climate Change with the title "Drought and aridity influence internal migration worldwide." For the University of Bologna, Raya Muttarak, Professor at the Department of Statistical Sciences "Paolo Fortunati" and Principal Investigator of the ERC Consolidator project "POPCLIMA: Population Dynamics under Global Climate Change," participated in the research.