Climatic shocks and internal migration: evidence from 442 million personal records in 64 countries
This paper examines whether and how climatic shocks influence individual migration decisions. The authors use census microdata across 64 countries over the period 1960 to 2012, covering 442 million individual records, combined with geo-referenced temperature and precipitation data summarized for each origin and destination administrative unit. Migration is identified when an individual changed a place of usual residence one, five, or ten years ago to a new major administrative unit in the same country. Given an exceptionally large number of observations, the authors apply a two-step approach to analyze the relationship between exposure to climatic shocks and migration. First, the authors use random forest models to uncover that in many countries climatic shocks are as important as better-known individual-level covariates in determining migration decisions. This observation serves as a yardstick for the second step of the analysis. For a subset of countries, where rainfall shocks play an important role in migration, the authors compare internal migration patterns across time by examining whether a region experiencing positive or negative rainfall shocks observed higher or lower migration. The authors find that negative rainfall shocks suppress outmigration particularly for low-income countries. The opposite is true for positive rainfall shocks whereby migration is found to increase, especially for lower-income countries. The finding supports the liquidity constraint argument whereby adverse climatic conditions can disrupt migration financing and consequently suppress ability to migrate.