Environmental migration? An overview of the literature

TL;DR

This paper systematically reviews and analyzes the literature on environmental factors influencing human migration, revealing small but significant effects and heterogeneity across different research clusters.

Contribution

It provides a comprehensive bibliometric and meta-analytic overview of empirical studies on environmental migration, identifying distinct clusters and heterogeneity in findings.

Findings

Small overall impact of environmental factors on migration.

Significant heterogeneity among different research clusters.

Evidence of convergence within specific clusters of literature.

Abstract

The literature on the relationship between environmental factors such as climatic changes and natural hazards and human mobility (both internal and international) is characterized by heterogeneous results: some contributions highlight the role of climate changes as a driver of migratory flows, while others underline how this impact is mediated by geographical, economic and the features of the environmental shock. This paper attempts to map this literature, focusing on economics and empirical essays. The paper improves on the existing literature: (a) providing systematic research of the literature through main bibliographic databases, followed by a review and bibliometric analysis of all resulting papers; (b) building a citation-based network of contributions, that hollows to identify four separate clusters of paper; (c) applying meta-analysis methods on the sample of 96 papers released between 2003 and 2020, published in an academic journal, working papers series or unpublished studies, providing 3,904 point estimates of the effect of slow-onset events and 2,065 point estimates of the effect of fast-onset events. Overall, the meta-analytic average effect estimates a small impact of slow- and rapid-onset variables on migration, however positive and significant. When the clustering of the literature is accounted for, however, a significant heterogeneity emerges among the four clusters of papers, giving rise to new evidence on the formation of club-like convergence of literature outcomes.