Climate variability and worldwide migration: current evidence and future projections

The literature linking climatic drivers and migration is growing, but there is still limited evidence and substantial uncertainty regarding future bilateral flows driven by climate stress on a global scale. The aim of this paper is to fill this gap by projecting changes in the flows of international migrants from medium-term population and climate change projections. We employ a bilateral gravity equation for emigration rates controlling for decadal weather averages of temperature, precipitation, droughts, and extreme precipitation in the origin countries. We use the parameter estimates of the gravity equation to estimate global, regional, and country-by-country emigration flows for several combinations of socio-economic development and climate change. Results indicate that global emigration flows are projected to increase to around 110 million in 2060 for SSP1 and RCP 4.5 and SSP5 and RCP 4.5; to 135 million for SSP5 and RCP 8.5; to 163 million for SSP3 and RCP 4.5. We report that changes in emigration flows are largely due to population growth in the origin countries.