How do weather shocks influence human mobility and poverty, and how will long-term climate change affect future migration over the course of the 21st century? These questions have gained unprecedented attention in public debates as global warming is already having severe impacts around the world, and prospects for the coming decades get worse. Low-latitude countries in general, and their agricultural areas in particular, have contributed the least to climate change but are the most adversely affected. The effect on people's voluntary and forced displacements is of major concern for both developed and developing countries. On 18 October 2019, Agence Française de Développement (AFD) and Luxembourg Institute of Socio-Economic Research (LISER) organized a workshop on Climate Migration with the aim of uncovering the mechanisms through which fast-onset variables (such as weather anomalies, storms, hurricanes, torrential rains, floods, landslides, etc.) and slow-onset variables (such as temperature trends, desertification, rising sea level, coastal erosion, etc.) influence both people's incentives to move and mobility constraints. This special issue gathers five papers prepared for this workshop, which shed light on (or predict) the effect of extreme weather shocks and long-term climate change on human mobility, and stress the implications for the development community.

Recent surveys of the literature on climate change and migration emphasize the important diversity of outcomes and approaches of the empirical studies. In this paper, we conduct a meta-analysis in order to investigate the role of the methodological choices of these empirical studies in finding some particular results concerning the role of climatic factors as drivers of human mobility. We code 51 papers representative of the literature in terms of methodological approaches. This results in the coding of more than 85 variables capturing the methodology of the main dimensions of the analysis at the regression level. These dimensions include authors' reputation, type of mobility, measures of mobility, type of data, context of the study, econometric methods, and last but not least measures of the climatic factors. We look at the influence of these characteristics on the probability of finding any effect of climate change, a displacement effect, an increase in immobility, and evidence in favor of a direct vs. an indirect effect. Our results highlight the role of some important methodological choices, such as the frequency of the data on mobility, the level of development, the measures of human mobility and of the climatic factors as well as the econometric methodology.

In this paper, we investigate the long-term effects of climate change on the mobility of working-age people. We use a world economy model that covers almost all the countries around the world, and distinguishes between rural and urban regions as well as between flooded and unflooded areas. The model is calibrated to match international and internal mobility data by education level for the last 30 years, and is then simulated under climate change variants. We endogenize the size, dyadic, and skill structure of climate migration. When considering moderate climate scenarios, we predict mobility responses in the range of 70–108 million workers over the course of the twenty-first century. Most of these movements are local or inter-regional. South–South international migration responses are smaller, while the South–North migration response is of the “brain drain” type and induces a permanent increase in the number of foreigners in OECD countries in the range of 6–9% only. Changes in the sea level mainly translate into forced local movements. By contrast, inter-regional and international movements are sensitive to temperature-related changes in productivity. Lastly, we show that relaxing international migration restrictions may exacerbate the poverty effect of climate change at origin if policymakers are unable to select/screen individuals in extreme poverty.

In light of increasing environmental stress and its likely implications for migration patterns, we conduct a cross-country individual-level analysis of the impact of self-reported exposure to environmental stress on people's migration intentions and their destination choice. We simultaneously model intentions to migrate domestically and internationally for 90 countries worldwide in 2010. We find that self-reported exposure to environmental stress increases the probability to intend to migrate both domestically and internationally in the coming year. In absolute terms, the largest impact is obtained for domestic migration, but controlling for the fact that this is the most common form of migration anyway, environmental stress particularly raises intraregional migration intentions. Overall, the effects on migration intentions to the different destinations are strongest in low- and middle-income countries in Africa and Latin America and the Caribbean, while in high-income countries, and in Europe particularly, environmental stress appears to spur only domestic migration intentions.

Migration is a common means of adaptation to weather shocks. Previous research has identified heterogeneous effects according to age, sex, and wealth, but little is still known about how marriage-related institutions affect such migration. Relying on a quasi-experimental identification strategy, we analyze marriage- and work-related migration in Malawi following large droughts, separating the effects for female and male migrants according to different age groups. The analysis based on stated motives of migration reveals marginal decreases in marriage-related migration among girls, but increases in marriage-related migration within districts for women in older age groups. We also find large increases in work-related between-district migration for boys, and to a smaller extent also for girls following severe drought. The results add to the evidence of the potentially adverse effects of migration as a coping mechanism following drought when other means of insurance do not exist.

Increasingly, studies are examining whether the incidence of natural disasters influences household migration. This paper examines whether the severity of natural disasters is important for migration decisions in Vietnam, rather than just examining their occurrence. Data for a sample of 1,003 farm households from the Vietnam Household Living Standard Survey are examined for the period 2006–2008. A residual generated regressor approach is adopted to isolate the direct impact of disasters on migration from the indirect impact they have on migration through reducing agricultural output and income. Findings suggest that more severe disasters are directly associated with a greater probability of migration. Furthermore, such outcomes are the same for poor households vis-à-vis their non-poor counterparts.