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

Abstract

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.

Policy challenges and responses to environmental non-migration

“…Whether the decision will be of their free will or compelled by some other external factors is generally determined by the unique social, political, environmental, and security context of the concerned person or group of persons 20 . It is not a linear decision but a complex outcome interrelated with many variable circumstances and factors at a range of spatial and temporal scales 14,25 that affects the livelihood conditions 26 . Thus, non-migration and migration are dynamic, intertwined processes that evolved through risk perception, risk tolerance, and selfefficacy 26 .…”

“…For instance, according to a global report on internal displacement, in 2021 alone, around 23.7 million people were displaced by disasters in 141 countries, of which 22.3 million were displaced by weather-related disasters 12 . There is limited empirical research demonstrating the exact types (forced or voluntary) and volume of environmental migrants and non-migrants [13][14][15] , and many studies confirm that only a fraction of the total number of people affected by disasters worldwide adopts the path of migration [16][17][18] .…”

“…But not everyone staying is trapped, rather many of them are voluntarily staying, given that they have resources, capabilities and aspirations to stay at risk 19 . As a result, this immobility has far-reaching implications for the current and future lives of this population as the climate change consequence is not only an immediate livelihoods threat but also contributes to their fragile livelihoods conditions 14,15,22 . The importance of addressing the needs of these non-migrants in the policy discourses has increasingly been emphasised 1 .…”