Coastal climate change, soil salinity and human migration in Bangladesh

Abstract

Climate change is not only altering weather patterns but also accelerating sea-level rise, leading to increased inundation and saline contamination of soils. Given projected sea-level rise, it is imperative to examine the extent to which farmers in coastal Bangladesh can adapt by diversifying economic activities before resorting to migration within and across borders. Here, to identify patterns in how households adapt to increased sea/freshwater flooding and soil salinity, we analyse nationally representative socioeconomic and migration data against a suite of environmental variables constructed at the sub-district level. Our results show that inundation alone has negligible effects on migration and agricultural production. However, gradual increases in soil salinity correspond to increasing diversification into aquaculture and internal migration of household members. Salinity is also found to have direct effects on internal and international migration even after controlling for income losses, with mobility restricted to certain locations within Bangladesh. Our study suggests that migration is driven, in part, by the adverse consequences of salinity on crop production.

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Fig. 1: Projected additional within-district migrants in coastal region of Bangladesh because of an increase in salinity from the first to fifth quintile.
Fig. 2: Projected additional out-of-district migrants from coastal region of Bangladesh because of an increase in salinity from the first to fifth quintile.

Data availability

The datasets generated during the current study and Stata dofiles utilized in the analysis are available upon request from the corresponding authors.

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Acknowledgements

We thank K. Dotzel, Y. Jia, M. Kedir and S. Vallury for research assistance and S. K.-H. Tseng for sharing his code; C. Kinnan and participants of the National Socio-Environmental Synthesis Center (SESYNC) Pursuit Working Group on ‘A Forecast of the Timing, Locations, Sequence and Likeliest Destinations of Populations Displaced by Sea Level Rise and Coastal Extremes’ for providing constructive feedback on earlier versions of the manuscript. Financial support from the National Science Foundation via the Belmont Forum/IGFA Program (ICER-1342644) and the SESYNC Pursuit programme is acknowledged.

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J.C. and V.M. designed the evaluation, constructed the datasets and wrote the paper. J.C conducted the migration and livelihood impact analysis, while V.M. contributed the visual projections based on the migration modelling.

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Correspondence to J. Chen or V. Mueller.

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Supplementary Tables 1–5

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Chen, J., Mueller, V. Coastal climate change, soil salinity and human migration in Bangladesh. Nature Clim Change 8, 981–985 (2018). https://doi.org/10.1038/s41558-018-0313-8

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