Climate Change and Migration: New Insights from a Dynamic Model of Out-Migration and Return Migration

Drought and migration: a case study of rural Mozambique

Migration is commonly seen as a last resort for households impacted by climate shocks, given the costs and risks that migration typically entails. However, pre-existing labor migration channels may facilitate immediate migration decisions in response to climate shocks. This study explores the relationship between migration and droughts in a rural Sub-Saharan setting from which men commonly migrate in search of non-agricultural employment. We use data from the Men's Migrations and Women's Lives project, which includes a longitudinal household panel conducted in rural Mozambique between 2006 and 2017, and combine it with the Standardized Precipitation Evapotranspiration Index, a high-resolution climate measure. The fixed-effect models assess the lagged impact of droughts on the labor migration status of male household heads. We find an immediate increase in migration following a drought, peaking in the first year, then diminishing in the second year, with a slight resurgence in the third year. However, by the sixth-year post-drought, the likelihood of being a migrant turns negative. These findings demonstrate the complex associations of climate shocks with labor migration in low-income rural settings.

Child Fostering in a Changing Climate: Evidence from Sub-Saharan Africa

An extensive social science literature has examined the effects of climate change on human migration. Prior studies have focused largely on the out-migration of working-age adults or entire households, with less attention to migration and other forms of geographic mobility among other age groups, including youth. In this study, we focus on the implications of climate variability for the movement of children by examining the association between climate exposures and the in- and out-fostering of children in sub-Saharan Africa. We link high-resolution temperature and precipitation records to data from the Demographic and Health Surveys for 23 sub-Saharan African countries. We fit a series of regression models to measure the overall associations between climate exposures and each outcome, and then evaluate whether these associations are moderated by socioeconomic status, the number of children in the household, and the prevalence of fostering in each country. Precipitation is positively associated with in-fostering overall, and these effects are especially strong among households who already have at least one child and in countries where child fostering is common. We find no overall relationship between either temperature or precipitation exposures and out-fostering, but we do detect significant effects among households with many children and those with more-educated heads. In sum, our findings suggest climate variability can influence child mobility, albeit in complex and in some cases context-specific ways. Given the socioeconomic and health implications of fostering, these results underline another pathway through which climate exposures can affect children's wellbeing. More broadly, this study shows that new attention to the links between climate variability, child fostering, and other understudied forms of spatial mobility is needed to fully understand the effects of climate change on human populations.

Immigrant Wealth Stratification and Return Migration: The Case of Mexican Immigrants in the United States During the Twentieth Century

Considerable wealth stratification exists between U.S.-born and foreign-born populations (Campbell and Kaufman 2006), with low wealth attainment documented among Mexican immigrants (Hao 2007). High rates of Mexican return migration (Azose and Raftery 2019) suggest that nonrandom selection into return migration on wealth is a potential driver of stratification. Existing theories do not conclusively predict asset accumulation among returnees versus stayers, and empirical research on return migration and wealth stratification is scarce. Combining data from the 2000 U.S. Health and Retirement Study and the 2001 Mexican Health and Aging Study to create a novel data set representing all Mexicans aged 50 and older with a history of migration to the United States and adopting a life course perspective, I find that return migration at younger and older ages is associated with higher wealth accumulation and might be a way to maximize assets at older ages. Thus, return migration may contribute to nativity-based wealth stratification in the United States. The study's findings point to the greater financial risks for new cohorts of immigrants aging in place, suggest caution in interpreting wealth stratification as a measure of mobility, and inform theories about the links between return migration and wealth across the life course.

Time to Mainstream the Environment into Migration Theory?

As with all social processes, human migration is a dynamic process that requires regular theoretical reflection; this article offers such reflection as related to the role of the natural environment in contemporary migration research and theory. A growing body of evidence suggests that environmental contexts are increasingly shifting social and ecological realities in ways that are consequential to migration theory. We review some of this evidence, providing examples applicable to core migration theories, including neoclassical economic and migration systems perspectives, the "push-pull" framework, and the new economics of labor migration. We suggest that neglecting consideration of the natural environment may yield misspecified migration models that attribute migration too heavily to social and economic factors particularly in the context of contemporary climate change,. On the other hand, failure to consider migration theory in climate scenarios may lead to simplistic projections and understandings, as in the case of "climate refugees". We conclude that migration researchers have an obligation to accurately reflect the complexity of migration's drivers, including the environment, within migration scholarship especially in the context of global climate change.

Drought and migration: An analysis of the effects of drought on temporary labor and return migration from a migrant-sending area in Nepal

Although the relationship between drought - a dimension of climate change - and migration has been explored in a number of settings, prior research has largely focused on out-migration and has not considered climate factors at the migrant destination. However, drought may impact not only out-migration, but also return migration, particularly in settings where temporary labor migration and agricultural reliance are common. Thus, considering drought conditions at origin and destinations is necessary to specify the effects of climate on migrant-sending populations. Using detailed data from the Chitwan Valley Family Study, a household panel study in a migrant-sending area in Nepal, we analyze the effect of drought at the neighborhood level on individual-level out-migration and drought at the origin district on return migration among adults from 2011 to 2017, assessing these associations among males and females separately. In mixed-effect discrete-time regressions, we find that neighborhood drought is positively associated with out-migration and return migration, both internally and internationally among males. Among females, drought is positively associated with internal out-migration and return migration, but not international migrations. We did not find an association between drought at the origin and return migration independent of drought status at the destination. Taken together, these findings contribute to our understanding of the complexity of the impacts of precipitation anomalies on population movement over time.

The Childhood Origins of Climate-Induced Mobility and Immobility

The literature on climate exposures and human migration has focused largely on assessing short-term responses to temperature and precipitation shocks. In this paper, we suggest that this common coping strategies model can be extended to account for mechanisms that link environmental conditions to migration behavior over longer periods of time. We argue that early-life climate exposures may affect the likelihood of migration from childhood through early adulthood by influencing parental migration, community migration networks, human capital development, and decisions about household resource allocation, all of which are correlates of geographic mobility. After developing this conceptual framework, we evaluate the corresponding hypotheses using a big data approach, analyzing 20 million individual georeferenced records from 81 censuses implemented across 31 countries in tropical Africa, Latin America, and Southeast Asia. For each world region, we estimate regression models that predict lifetime migration (a change in residence between birth and ages 30-39) as a function of temperature and precipitation anomalies in early life, defined as the year prior to birth through age four. Results suggest that early-life climate is systematically associated with changes in the probability of lifetime migration in most regions of the tropics, with the largest effects observed in sub-Saharan Africa. In East and Southern Africa, the effects of temperature shocks vary by sex and educational attainment and in a manner that suggests women and those of lower socioeconomic status are most vulnerable. Finally, we compare our main results with models using alternative measures of climate exposures. This comparison suggests climate exposures during the prenatal period and first few years of life are particularly (but not exclusively) salient for lifetime migration, which is most consistent with the hypothesized human capital mechanism.

Migration and Fuel Use in Rural Zambia

What is the effect of migration on fuel use in rural Zambia? Opportunities to increase income can be scarce in this setting; in response, households may pursue a migration strategy to increase resources as well as to mitigate risk. Migrant remittances may make it possible for households to shift from primary reliance on firewood to charcoal, and the loss of productive labor through migration may reinforce this shift. This paper uses four waves of panel data collected as part of the Child Grant Programme in rural Zambia to examine the connection between migration and the choice of firewood or charcoal as cooking fuel and finds evidence for both mechanisms. Importantly, this paper considers migration as a process, including out- as well as return migration, embedding it in the context of household dynamics generally. Empirical results suggest that while migration helps move households away from firewood as a fuel source, return migration moves them back, but because firewood is more common, the overall effect of migration is to shift households away from primary reliance on firewood towards charcoal.

Population Responses to Environmental Change: Looking Back, Looking Forward

Over the past two decades, population researchers have engaged in a far-reaching and productive program of research on demographic responses to changes in the natural environment. This essay "looks back" to the origins of these developments, identifying pivotal agenda-setting moments in the 1990s and tracing the impact on contemporary research. The essay also "looks forward" to identify critical gaps and challenges that remain to be addressed and to set an agenda for future research on population responses to environmental change. It recommends that the multidimensionality of environmental contexts and change be fully embraced, long run as well as short term effects be investigated, variability in the effects of environmental change in relation to social institutions, policy implementation, and environmental context be examined, movement between contexts as well as change in situ as sources of environmental change be considered, and interconnections among demographic processes in response to environmental change be explored. Taking these steps will position demographers to contribute significantly to a larger and deeper understanding of environmental change and its consequences, locally, regionally, and globally.