Climatic Variability and Internal Migration in Asia: Evidence from Integrated Census and Survey Microdata

The potential effects of climate change on human migration have received widespread attention, driven in part by concerns about possible large-scale population displacements. Recent studies demonstrate that climate-migration linkages are often more complex than commonly assumed, and climatic variability may increase, decrease, or have null effects on migration. However, the use of non-comparable analytic strategies across studies makes it difficult to disentangle substantive variation in climate effects from methodological artifacts. We address this gap by using census and survey micro-data from six Asian countries (n=54,987,838), which today are collectively home to nearly one-quarter of the world’s population, to measure climate effects on interprovincial migration. We examine climate effects overall and among sub-populations defined by age, sex, education, and country of residence. We also evaluate whether climate effects differ according to the distance and type of migration. We find non-linear precipitation effects across the sample, with exposure to precipitation deficits leading to substantively large reductions in out-migration. Both precipitation and temperature effects vary among focal sub-populations. Precipitation deficits reduce internal migration to both adjacent and non-adjacent provinces and, among the subset of samples with data on the reasons for migration, also reduce the probability of work-related moves. Temperature anomalies reduce work-, education-, and family-related moves. Our findings provide evidence of climate-related reductions in migration (i.e., trapped populations) and suggest these effects are driven largely by economic factors. Our analysis complements similar uses of harmonized data and methods in studies from South America and sub-Saharan Africa, which collectively reveal significant heterogeneity in demographic responses to climate variability around the world.