How do environmental stressors influence migration? A meta-regression analysis of environmental migration literature

Shuai Zhou; Guangqing Chi

doi:10.4054/DemRes.2024.50.2

Volume 50 - Article 2 | Pages 41–100

How do environmental stressors influence migration? A meta-regression analysis of environmental migration literature

By Shuai Zhou, Guangqing Chi

Date received:

15 Jun 2022

Date published:

5 Jan 2024

Word count:

7575

Keywords:

environmental, instrumental variables, meta analysis, migration, partial correlation coefficient, weighted regression

DOI:

10.4054/DemRes.2024.50.2

Replicable Material:

demographic-research.50-2 (zip file, 394 kB)
readme.50-2 (text file, 1 kB)

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Abstract

Background: The amount of literature on environmental migration is increasing. However, existing studies exhibit contradictory results. A systematic synthesis of the environment–migration relationship is much needed.

Objective: This study summarizes research findings, calculates the effect sizes of environmental stressors, identifies publication bias, and investigates heterogeneous environmental effects on migration.

Methods: We collected 3,380 estimates from 128 studies published between 2000 and 2020 to explore the environment–migration relationship and performed weighted instrumental variable regression to unveil the heterogeneous environmental effects on out- and net migration.

Results: The majority of environmental stressors were not important predictors of out- and net migration. Among the results showing environmental impacts on migration, 58% and 68% reported that environmental stressors increased out- and net migration, respectively, while 58% reported that environmental stressors decreased in-migration. The overall environmental impact on migration was small; however, disaster-related stressors showed a medium effect, and rapid-onset stressors had a stronger impact than slow-onset ones. Multivariate meta-regression analyses demonstrated that environmental stressors were more likely to trigger internal migration than international migration and that developed countries were less likely to experience out-migration. Rapid-onset environmental stressors did not increase out-migration but played an important role in decreasing net migration toward environmentally stressed areas. Meanwhile, we also found a publication bias toward studies showing a positive relationship between environmental stressors and migration in the previous environmental migration literature.

Conclusions: Environmental stressors may affect migration; however, the environmental effect depends on migration measurements, environmental stressors' forces and rapidity, and the context in which migration takes place.

Contribution: This study contributes to migration studies by synthesizing and validating the environment–migration relationship and enhancing our understanding of how and under what circumstances environmental stressors may affect migration.