Climate-Induced Migration Patterns in Vulnerable Coastal Communities
DOI:
https://doi.org/10.5281/zenodo.22802365Keywords:
environmental migration, coastal displacement, sea level rise, soil salinization, storm surge, shoreline erosion, household survey, Bangladesh, Mekong Delta, West Africa, migration decision-makingAbstract
Coastal deltas and low-lying shorelines host a large and growing share of the world's population under increasing
exposure to sea level rise, soil and water salinization, tropical cyclones and storm surge, and progressive shoreline
erosion, yet how these overlapping hazards translate into household migration decisions remains contested, with
evidence pointing to both displacement and, in many settings, reduced mobility among the most affected
households. We surveyed 2,412 households across nine sites in three climate-exposed deltaic regions, the
Ganges-Brahmaputra-Meghna delta in southwestern Bangladesh, the Mekong Delta in southern Vietnam, and the
Saloum and Volta deltas of Senegal and Ghana, and linked household-reported exposure and migration histories
(2008-2022) to site-level shoreline change and inundation frequency derived from a Landsat- and Sentinel-2-based
surface water time series. Overall, 31.4% of surveyed households reported at least one migrant member since
2008, but migration type differed sharply by driver: salinization and progressive erosion were associated
predominantly with permanent, longer-distance out-migration, while cyclone and storm-surge exposure were
associated mainly with short-duration, short-distance displacement followed by return. In multivariate models, each
10-percentage-point increase in a household's land under saline intrusion was associated with a
4.1-percentage-point higher probability of permanent migration (95% CI 2.6-5.6), while landholding size and asset
wealth showed a non-monotonic relationship with migration, rising with wealth at low-to-moderate asset levels
before declining among the poorest quintile, consistent with resource constraints on migration among the most
vulnerable rather than a simple linear escape response. Remittances from migrant household members financed an
estimated 38% of embankment and homestead-raising investments among migrant-sending households in
Bangladesh and Vietnam, suggesting migration and in-place adaptation function partly as complements rather than
substitutes. We conclude that climate-induced coastal migration is heterogeneous by hazard type, selective by
household resources, and entangled with in-place adaptation in ways that resist a single displacement narrative,
with direct implications for how planned relocation and adaptation finance are targeted.
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