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on the sample of 96 papers released between 2003 and 2020, published in an academic journal, working papers series or unpublished studies, providing 3,904 point estimates of the effect of slow-onset events and 2,065 point estimates of the effect of fast-onset events.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.

This article provides a comprehensive quantitative overview of the literature on the relationship between environmental changes and human migration. It begins with a systematic approach to bibliographic research and offers a bibliometric analysis of the empirical contributions. Specifically, we map the literature and conduct systematic research using main bibliographic databases, reviews, and bibliometric analysis of all resulting papers. By constructing a citation-based network, we identify four separate clusters of papers grouped according to certain characteristics of the analysis and resulting outcomes. Finally, we apply a meta-analysis to a sample of 96 published and unpublished studies between 2003 and 2020, providing 3,904 point estimates of the effect of slow-onset events and 2,065 point estimates of the effect of fast-onset events.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 on migration is small for both slow- and rapid-onset events; however, it is positive and significant. Accounting for the clustering of the literature, which highlights how specific common features of the collected studies influence the magnitude of the estimated effect, reveals a significant heterogeneity among the four clusters of papers. This heterogeneity gives rise to new evidence on the formation of club-like convergence of literature outcomes. JEL Codes: C83, F22, J61, Q51, Q54, Q56.