A new study concludes that rising temperatures have trimmed rural-to-urban migration within very poor nations while slightly increasing it in middle-income countries.
Why it matters: The analysis, released via the National Bureau of Economic Research, provides a deeper understanding about how warming has already begun affecting human movement — and will in the future.
The impact: "We project that expected warming in the next century will encourage further urbanization in middle-income countries such as Argentina, but it will slow down urban transition in poor countries like Malawi and Niger."
What they did: Researchers with UC Davis and the University of Idaho looked at migration data for huge numbers of relatively small geographic "cells" worldwide from 1970 to 2000.
What they found: The middle-income group showed the most internal migration to cities. A big takeaway: Declines in rural productivity, including lower crop yields stemming from climate change, have different effects on poor vs. middle-income nations.
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