The Environmental Dimensions of Migration

Weather deviations linked to undocumented migration and return between Mexico and the United States

As the world's climate continues to change, human populations are exposed to increasingly severe and extreme weather conditions that can promote migration. Here, we examine how extreme weather influences the likelihood of undocumented migration and return between Mexico and the United States. We used data from 48,313 individuals observed between 1992 and 2018 in 84 Mexican agricultural communities. While controlling for regional and temporal confounding factors, we related individual decisions to migrate to the United States without documents and subsequently return to Mexico with lagged weather deviations from the historical norm during the corn-growing season (May to August). Undocumented migration was most likely from areas experiencing extreme drought, and migrants were less likely to return to their communities of origin when extreme weather persisted. These findings establish the role of weather shocks in undocumented Mexican migration to, and eventual settlement in, the United States. The findings also suggest that extreme weather conditions, which are likely to increase with climate change, promote clandestine mobility across borders and, thus, expose migrants to risks associated with crossing dangerous terrain and relying upon smugglers.

Mobility ideation due to water problems during historic 2022 drought associated with livestock wealth, water and food insecurity, and fingernail cortisol concentration in northern Kenya

Climate change is triggering environmental mobility through chronic water problems and punctuated events. Thinking about moving locations, or "mobility ideation", is the precursor to migration intentionality and actual migration. Drawing on the embodiment construct, this study examines how the worst drought in recent history in the Horn of Africa affected water-related mobility ideation and, in turn, fingernail cortisol concentration (FCC), a chronic stress biomarker, among Daasanach semi-nomadic pastoralists in northern Kenya. To address these questions, we primarily draw on survey, anthropometric, water quality, and biomarker data among 175 adults living in seven communities in 2022. We used mixed-effects ordered logistic regression to test how livestock wealth, water insecurity, food insecurity, and anxiety/depression symptom scores were associated with household mobility ideation. We then used generalized linear models to test the association between mobility ideation on FCC. Thinking about moving at least once due to water problems increased from pre-drought in 2019 (55%) to during the drought in 2022 (92%), while actual mobility declined. Livestock wealth, while associated with actual mobility in the prior year, was protective against increased mobility ideation, while water insecurity, food insecurity, and anxiety/depression symptoms were associated with greater odds of thinking of leaving in 2022. Compared to adults who did not consider moving, those who considered moving rarely, sometimes, and often had FCC levels 18.1% higher (95% CI, 1.01-1.38; p = 0.039), 19.4% higher (1.01-1.41; p = 0.040), and 32.3% higher (1.01-1.73; p = 0.039), respectively, with results consistent in sensitivity analyses. Extreme climatic events in water scarce regions may increase mobility ideation through worsened experiential indicators of well-being and resource insecurity. Mobility ideation may capture measures of adversity suffered by pastoralists and signify climate distress. This research broadens understanding of how droughts get under the skin by leading to resource insecurity and triggering thoughts of moving, which increases chronic stress.

Causal discovery reveals complex patterns of drought-induced displacement

The increasing frequency and severity of droughts present a significant risk to vulnerable regions of the globe, potentially leading to substantial human displacement in extreme situations. Drought-induced displacement is a complex and multifaceted issue that can perpetuate cycles of poverty, exacerbate food and water scarcity, and reinforce socio-economic inequalities. However, our understanding of human mobility in drought scenarios is currently limited, inhibiting accurate predictions and effective policy responses. Drought-induced displacement is driven by numerous factors and identifying its key drivers, causal-effect lags, and consequential effects is often challenging, typically relying on mechanistic models and qualitative assumptions. This paper presents a novel, data-driven methodology, grounded in causal discovery, to retrieve the drivers of drought-induced displacement within Somalia from 2016 to 2023. Our model exposes the intertwined vulnerabilities and the leading times that connect drought impacts, water and food security systems along with episodes of violent conflict, emphasizing that causal mechanisms change across districts. These findings pave the way for the development of algorithms with the ability to learn from human mobility data, enhancing anticipatory action, policy formulation, and humanitarian aid.

Complex nexus: Economic development, rural-to-urban migration, and transition to adulthood in China

Transition to adulthood in low- and middle-come countries (LMIC) has increasingly been diversified and individualized. Economic development and migration are often cited as reasons for diversification but have been analytically examined interactively. To examine the complex linkages between development, migration, and transition to adulthood, we use China data to cover a decade when it has experienced rapid economic development, a large flow of rural-to-urban migration, and changes in the transition to adulthood. Applying the latent class analysis and multinomial logistic regression on the Chinese General Social Survey 2008 and 2017, we obtain three main findings. First, economic development increases the diversification of the transition to adulthood. Second, rural-to-urban migration has a greater impact on the postponement than on other pathways. Third, the joint impact of economic development and migration is not evident: the change do not differ between men and women as well as young adults of different migration experience. These findings collectively imply signs of the diversification of transition to adulthood in China, but also entail the individualization behind it.

Rare and highly destructive wildfires drive human migration in the U.S

The scale of wildfire impacts to the built environment is growing and will likely continue under rising average global temperatures. We investigate whether and at what destruction threshold wildfires have influenced human mobility patterns by examining the migration effects of the most destructive wildfires in the contiguous U.S. between 1999 and 2020. We find that only the most extreme wildfires (258+ structures destroyed) influenced migration patterns. In contrast, the majority of wildfires examined were less destructive and did not cause significant changes to out- or in-migration. These findings suggest that, for the past two decades, the influence of wildfire on population mobility was rare and operated primarily through destruction of the built environment.

Climate-health risk (In)visibility in the context of everyday humanitarian practice

Nongovernmental migrant shelters in Mexico play a key role in documenting the factors that shape forced migration from Central America. Existing intake protocols in shelters are largely oriented to humanitarian legal frameworks that determine eligibility for international protection based on interpersonal violence and political persecution. This qualitative study calls attention to how existing humanitarian logics may obscure climate- and health-related disruptions as drivers of forced migration from Central America in the context of everyday humanitarian practice. In May 2022 we compared migrant's responses (n = 40) to a standardized intake protocol at a nongovernmental humanitarian migrant shelter in Mexico with responses to semi-structured interviews that focused on migrants' perceptions of climate change and health as drivers of forced displacement. We found that slow- and rapid-onset climatic disruptions; illness and disease; and various forms of violence and repression are often interrelated drivers of forced displacement. Comparing intake protocols and in-depth interview responses, we found that climate- and health-related drivers of forced displacement are rarely documented. These findings speak to the importance of critically examining everyday humanitarian practices in the context of ongoing advocacy that calls for climate-related disruptions to be integrated into existing humanitarian protection frameworks.

Understanding the global subnational migration patterns driven by hydrological intrusion exposure

Amid the escalating global climatic challenges, hydrological risks significantly influence human settlement patterns, underscoring the imperative for an in-depth comprehension of hydrological change's ramifications on human migration. However, predominant research has been circumscribed to the national level. The study delves into the nonlinear effects of hydrological risks on migration dynamics in 46,776 global subnational units. Meanwhile, leveraging remote sensing, we procured globally consistent metrics of hydrological intrusion exposure, offering a holistic risk assessment encompassing hazard, exposure, and vulnerability dimensions, thus complementing previous work. Here, we show that exposure is the primary migration driver, surpassing socioeconomic factors. Surrounding disparities further intensified exposure's impact. Vulnerable groups, especially the economically disadvantaged and elderly, tend to remain in high-risk areas, with the former predominantly migrating within proximate vicinities. The nonlinear analysis delineates an S-shaped trajectory for hydrological exposure, transitioning from resistance to migration and culminating in entrapment, revealing dependence on settlement resilience and adaptability.

Drivers of domestic migration in Vietnam: The characteristics of the households and their heads, environmental factors and living conditions

Vietnam has achieved significant economic growth, poverty reduction, and social transformation since its 1986 major economic reform. However, industrialization, a key pillar supporting this achievement, has resulted in massive domestic migration from certain parts of the country into industrialized provinces mainly located in the south of Vietnam, leading to various challenges for society. This study investigates the effects of the characteristics of Vietnamese households and their heads, environmental factors, and living conditions of the households in the regions where they have decided to leave behind for a migration decision on domestic migration. Our study also compares the migration trends in the past decade using the Vietnamese Household Living Standard Surveys (VHLSS) in 2010 and 2020, together with a logit model. We find that the average probability that a household and their members migrate is about 10 per cent in 2010, reduced to approximately 6.8 per cent in 2020. Our empirical findings also confirm that a migration decision is strongly associated with the characteristics of the households and their heads, particularly for the household size and the educational level of the household head. The average radiation and rainfall are also associated with a migration decision. Weather temperature, water sources, and electricity supply also play an essential role in Vietnamese households' migration decisions. Policy implications have emerged based on these empirical findings that the Vietnamese government should consider.

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.

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

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.

Exploring interactions between socioeconomic context and natural hazards on human population displacement

Climate change is leading to more extreme weather hazards, forcing human populations to be displaced. We employ explainable machine learning techniques to model and understand internal displacement flows and patterns from observational data alone. For this purpose, a large, harmonized, global database of disaster-induced movements in the presence of floods, storms, and landslides during 2016-2021 is presented. We account for environmental, societal, and economic factors to predict the number of displaced persons per event in the affected regions. Here we show that displacements can be primarily attributed to the combination of poor household conditions and intense precipitation, as revealed through the interpretation of the trained models using both Shapley values and causality-based methods. We hence provide empirical evidence that differential or uneven vulnerability exists and provide a means for its quantification, which could help advance evidence-based mitigation and adaptation planning efforts.

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.

A prospective cohort study linking migration, climate, and malaria risk in the Peruvian Amazon

Migration is an important risk factor for malaria transmission for malaria transmission, creating networks that connect Plasmodium between communities. This study aims to understand the timing of why people in the Peruvian Amazon migrated and how characteristics of these migrants are associated with malaria risk. A cohort of 2,202 participants was followed for three years (July 2006 - October 2009), with thrice-weekly active surveillance to record infection and recent travel, which included travel destination(s) and duration away. Migration occurred more frequently in the dry season, but the 7-day rolling mean (7DRM) streamflow was positively correlated with migration events (OR 1.25 (95% CI: 1.138, 1.368)). High-frequency and low-frequency migrant populations reported 9.7 (IRR 7.59 (95% CI:.381, 13.160)) and 4.1 (IRR 2.89 (95% CI: 1.636, 5.099)) times more P. vivax cases than those considered non-migrants and 30.7 (IRR 32.42 (95% CI: 7.977, 131.765)) and 7.4 (IRR 7.44 (95% CI: 1.783, 31.066)) times more P. falciparum cases, respectively. High-frequency migrants employed in manual labour within their community were at 2.45 (95% CI: 1.113, 5.416) times higher risk than non-employed low-frequency migrants. This study confirms the importance of migration for malaria risk as well as factors increasing risk among the migratory community, including, sex, occupation, and educational status.

Compelled and constrained migration: restrictions to migration agency in the Marshall Islands

Migration as adaptation implies agency, yet environmental and non-environmental factors and their interactions may limit the availability of adaptation options, including migration. This study investigates migration agency in the Marshall Islands, particularly the role of geographic isolation and climate change. Interviews with internal migrants living in Majuro and members of government and civil society reveal how social, economic, cultural, and environmental factors shape migration contexts. Results suggest that geographic isolation-related factors may increase likelihoods of simultaneously more compelled and more constrained moves, particularly as climate change impacts increase. Climate change-related impacts on resource-dependent livelihoods may compel migration in search of new economic opportunities. However, worsening environmental conditions may also exacerbate cost-related migration constraints by reducing the resources available to support migration.

Exploring spatial feedbacks between adaptation policies and internal migration patterns due to sea-level rise

Climate change-induced sea-level rise will lead to an increase in internal migration, whose intensity and spatial patterns will depend on the amount of sea-level rise; future socioeconomic development; and adaptation strategies pursued to reduce exposure and vulnerability to sea-level rise. To explore spatial feedbacks between these drivers, we combine sea-level rise projections, socioeconomic projections, and assumptions on adaptation policies in a spatially-explicit model ('CONCLUDE'). Using the Mediterranean region as a case study, we find up to 20 million sea-level rise-related internal migrants by 2100 if no adaptation policies are implemented, with approximately three times higher migration in southern and eastern Mediterranean countries compared to northern Mediterranean countries. We show that adaptation policies can reduce the number of internal migrants by a factor of 1.4 to 9, depending on the type of strategies pursued; the implementation of hard protection measures may even lead to migration towards protected coastlines. Overall, spatial migration patterns are robust across all scenarios, with out-migration from a narrow coastal strip and in-migration widely spread across urban settings. However, the type of migration (e.g. proactive/reactive, managed/autonomous) depends on future socioeconomic developments that drive adaptive capacity, calling for decision-making that goes well beyond coastal issues.

Updated assessment of occupational safety and health hazards of climate change

Workers, particularly outdoor workers, are among the populations most disproportionately affected by climate-related hazards. However, scientific research and control actions to comprehensively address these hazards are notably absent. To assess this absence, a seven-category framework was developed in 2009 to characterize the scientific literature published from 1988-2008. Using this framework, a second assessment examined the literature published through 2014, and the current one examines literature from 2014-2021. The objectives were to present literature that updates the framework and related topics and increases awareness of the role of climate change in occupational safety and health. In general, there is substantial literature on worker hazards related to ambient temperatures, biological hazards, and extreme weather but less on air pollution, ultraviolet radiation, industrial transitions, and the built environment. There is growing literature on mental health and health equity issues related to climate change, but much more research is needed. The socioeconomic impacts of climate change also require more research. This study illustrates that workers are experiencing increased morbidity and mortality related to climate change. In all areas of climate-related worker risk, including geoengineering, research is needed on the causality and prevalence of hazards, along with surveillance to identify, and interventions for hazard prevention and control.

The impact of social capital and social environmental factors on mental health and flourishing: the experiences of asylum-seekers in France

BACKGROUND

There is growing interest on how social capital and related social environmental factors impact overall population health and well-being. The nature of asylum-seekers' social environment alters once they migrate to a new context and these changes influence their mental health and well-being. However, there is limited scholarship on how these social environmental factors impact the mental health, well-being, and capacity to flourish of asylum-seekers.

METHODS

The aim of the study, therefore, was to examine how specific social environmental factors-social networks, social support, and social cohesion at various levels (micro, meso, and macro)-influence the mental health, well-being, and capacity to flourish of asylum-seekers in France. In collaboration with a community-based organization, we used a qualitative research design to conduct 120 semi-structured interviews with asylum-seekers in France.

RESULTS

The emerging salient themes depicted how the asylum-seekers' usual informal social networks comprised of family and friends had been disrupted since they migrated to France, which impacted their mental health and well-being. Conversely, staying connected with their informal transnational social networks via social media and developing ties with new local informal and formal social networks allowed them to receive different forms of social support, and buffered some of the negative mental health consequences. However, the lack of social cohesion due to a lack of belonging, marginalization, and current harmful migration-related policies impeded asylum-seekers' capacity to flourish.

CONCLUSION

While social support derived from social networks buffered some negative impacts on mental health and well-being, the overall lack of social cohesion ultimately impeded asylum-seekers' capacity to flourish within their host communities, which was further exacerbated by harmful migration policies of exclusion within France. Introducing more inclusive policies related to the governance of migration and an intersectoral approach that views health in all policies is key to promoting social cohesion and flourishing among asylum-seekers in France.

How do migration decisions and drivers differ against extreme environmental events?

Migration is often understood to be a livelihood strategy to cope with the effects of environmental threats and climate change. Yet, the extent to which migration decisions differ due to the type, severity, and frequency of environmental events has been little explored. This paper employs household surveys in southwestern Bangladesh to explore this research gap. A multinominal regression model is used to simulate reported future migration decisions (200 sample households) in the context of both rapid-onset (i.e. cyclone and flood) and slow-onset (salinity, siltation, and riverbank erosion) environmental phenomena. Results show: i) previous disaster experience and increasing conflict in the community motivate migration in the near future in the context of slow-onset phenomena (salinity); (ii) economic strength and self-efficacy increase non-migration intention in both contexts of sudden and slow-onset events; and (iii) the extent and pattern of these influences on migration differ across demographics, including education, religion, and age. Importantly, this analysis shows that the relationship between migration decisions and the type, severity, and frequency of environmental events is influenced by socioeconomic conditions. Therefore, this research supports future adaptation planning specifically tailored to the type and exposure of extreme environmental events.

Natural resources modulate the nexus between environmental shocks and human mobility

In the context of natural resource degradation, migration can act as means of adaptation both for those leaving and those supported by remittances. Migration can also result from an inability to adapt in-situ, with people forced to move, sometimes to situations of worse or of the same exposure to environmental threats. The deleterious impacts of resource degradation have been proposed in some situations to limit the ability to move. In this contribution, we use remote sensed information coupled with population density data for continental Africa to assess quantitatively the prevalence of migration and immobility in the context of one cause of resource degradation: drought. We find that the effect of drought on mobility is amplified with the frequency at which droughts are experienced and that higher income households appear more resilient to climatic shocks and are less likely to resort to mobility as an adaptation response.

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.

The Measurement of Precarious Work and Market Conditions: Insights from the COVID-19 Disruption on Sample Selection

The precarious work construct combines employment instability and employment-contingent outcomes. Yet, I argue that confining the scope of the investigation to employed individuals creates a sample selection that disguises the heterogeneous nature of employment instability. The COVID-19 skyrocketing unemployment rate provides both a compelling motivation and a unique opportunity to revisit the construct of precarious work. Using pre-COVID and COVID-19 era data of the working-age population in Israel, the results demonstrate that by pushing less stable individuals out of employment, the COVID-19 recession strengthened the negative relationship between volatility and employment opportunities and accentuated sample selection. Because the selection into employment was not random, this introduces a bias into the measurement of precarious work, one that is more severe during a recession than in a full-employment market. The discussion highlights the broader significance of this lacuna and suggests a way to hone the conceptualization and operationalization of the precarious work construct.

Post-disaster (im)mobility aspiration and capability formation: case study of Southern California wildfire

Scholarship on the environmental dimensions of migration demonstrates the complex interplay of climatic and non-climatic factors which combine to create a potential for migration. Yet in times of environmental crisis or change, not everyone aspires to or is capable of moving to reduce their vulnerability. When, why, and how populations vulnerable to hazard risks decide not to migrate remains a significant gap in our understanding of the migration-environment relationship. Analysis of data from 38 qualitative interviews shows how Los Angeles County residents-after surviving the 2018 Woolsey Fire-developed aspirations to stay and/or rebuild, depending on the attachments and meanings associated with their communities. This paper also seeks to clarify the concept of capabilities to stay by considering separately the capabilities to return and rebuild from the capabilities to cultivate preparedness. Many who stayed also worked to strengthen community resilience to alleviate concerns of future wildfire risk. Some residents expressed individual commitments to stay and defend homes during future fires, while well-equipped volunteer fire brigades have proliferated in more affluent areas. Community mobilizations pressured local government and fire services to address the perceived institutional failure during previous fire responses and fostered feelings of collective efficacy among residents which increased their confidence to remain in high wildfire risk communities.

The Migration Response to Food Insecurity and Household Shocks in Southwestern Ethiopia, 2005–2008

This article examines how severe food insecurity and other shocks impact internal and international migration in southwestern Ethiopia using longitudinal survey data collected between 2005 and 2008 from a random sample of urban and rural households. We found an elevated risk of internal and international migration among sons and daughters in households that experienced severe food insecurity or farm loss. A household member's illness or death also significantly increased the risk of internal migration regardless of a household member's relationship with the household head. We also found that the effects of severe food insecurity and the other shocks were additive. With each additional shock, the risks of migration incrementally increased. This article provides compelling evidence of an international and an internal migration response to food insecurity and other shocks in a context where the prevalence of international migration is increasing and the potential for future international migration is substantial. These results challenge conventional wisdom in the migration literature that food insecurity and other household shocks will have larger relative effects on internal compared to international migration.

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.

The COVID-19 pandemic and residential mobility intentions in the United States: Evidence from Google Trends data

The COVID-19 pandemic has disrupted people's lives through economic challenges, closure of worksites and schools and increased health risks. These disruptions can trigger new residential needs and preferences, but little research has been done regarding the impact of the COVID-19 pandemic on moving intentions. We theorized how the pandemic could influence intentions of making different types of residential moves. Using Google Trends data, we conducted a time-series analysis to assess the transitory, short-term and long-lasting changes in various types of mobility intentions since the pandemic. Results show that thoughts about temporary relocation surged at the onset of the COVID-19 epidemic and then experienced a long-term decrease. Intentions to move through housing purchases and rentals briefly declined at the beginning of the pandemic but then surpassed their normal levels in the following months. Thoughts about moving in with family or parents increased by almost 50% during the pandemic. These trends were also reflected in Google searches for moving services, which exhibited an initial decline followed by a long-term increase. The results demonstrate that the COVID-19 pandemic has not only posed obstacles that lowered moving intentions but also has created new needs and desires for moving.

Universal Climate Thermal Index as a prognostic tool in medical science in the context of climate change: A systematic review

The assessment of the impact of meteorological factors on the epidemiology of various diseases and on human pathophysiology and physiology requires a comprehensive approach and new tools independent of currently occurring climate change. The thermal comfort index, i.e., Universal Climate Thermal Index (UTCI), is gaining more and more recognition from researchers interested in such assessments. This index facilitates the evaluation of the impact of cold stress and heat stress on the human organism and the assessment of the incidence of weather-related diseases. This work aims at identifying those areas of medical science for which the UTCI was applied for scientific research as well as its popularization among clinicians, epidemiologists, and specialists in public health management. This is a systematic review of literature found in Pubmed, Sciencedirect and Web of Science databases from which, consistent with PRISMA guidelines, original papers employing the UTCI in studies related to health, physiological parameters, and epidemiologic applications were extracted. Out of the total number of 367 papers identified in the databases, 33 original works were included in the analysis. The selected publications were analyzed in terms of determining the areas of medical science in which the UTCI was applied. The majority of studies were devoted to the broadly understood mortality, cardiac events, and emergency medicine. A significant disproportion between publications discussing heat stress and those utilizing the UTCI for its assessment was revealed.

Operationalizing and empirically identifying populations trapped in place by climate and environmental stressors in Mexico

In this paper, we propose a guiding operational definition and corresponding set of empirical steps to identify and study trapped populations. Trapped populations consist of actors who are highly vulnerable to climate and environmental stressors given limited resources (economic, social, etc.), which limit their ability to adapt to these stressors in-situ or by choosing to migrate. Informed by both insights and omissions from prior theoretical and empirical research, we propose a guiding operational definition of trapped populations that appreciates and incorporates actors' limited resources and their migration intentions against the backdrop of climate and environmental stressors. As it should, our operational definition points to a specific set of operations, or steps, which can be followed to empirically identify and study trapped populations. Using data from the Mexican Family Life Survey (MxFLS), we detail the steps permitting both retrospective and prospective identification of trapped populations. We conclude by discussing the strengths and weaknesses of our operational definition and empirical approach, as well as possible extensions.

Demography: Fast and Slow

Scientific ideas on the human population tend to be rooted in a "slow demography" paradigm, which emphasizes an inertial, predictable, self-contained view of population dynamics, mostly dependent on fertility and mortality. Yet, demography can also move fast. At the country level, it is crucial to empirically assess how fast demography moves by taking migratory movements into account, in addition to fertility and mortality. We discuss these ideas and present new estimates of the speed of population change, that is, country-level population turnover rates, as well as the share of turnover due to migration, for all countries in the world with available data between 1990 and 2020. Population turnover is inversely related to population size and development, and migratory movements tend to become important factors in shaping demography for both small and highly developed countries. Longitudinally, we analyze annual turnover data for Italy and Germany, documenting the changing speed of population change over time and its determinants. Accepting the "fast and slow" demography perspective has several implications for science and policy, which we discuss.

Modeling human migration driven by changing mindset, agglomeration, social ties, and the environment

Migration is an adaptation strategy to unfavorable conditions and is governed by a complex set of socio-economic and environmental drivers. Here we identified important drivers relatively underrepresented in many migration models-CHanging mindset, Agglomeration, Social ties, and the Environment (CHASE)-and asked: How does the interplay between these drivers influence transient dynamics and long-term outcomes of migration? We addressed this question by developing and analyzing a parsimonious Markov chain model. Our findings suggest that these drivers interact in nonlinear and complex ways. The system exhibits legacy effects, highlighting the importance of including migrants' changing priorities. The increased characteristic population size of the system counter-intuitively leads to fewer surviving cities, and this effect is mediated by how fast migrants change their mindsets and how strong the social ties are. Strong social ties result in less diverse populations across cities, but this effect is influenced by how many cities remain. To our knowledge, this is the first time that these drivers are incorporated in one coherent, mechanistic, parsimonious model and the effects of their interplay on migration systematically studied. The complex interplay underscores the need to incorporate these drivers into mechanistic migration models and implement such models for real-world cases.

Anticipating sea-level rise and human migration: A review of empirical evidence and avenues for future research

Sea-level rise (SLR) threatens millions of people living in coastal areas through permanent inundation and other SLR-related hazards. Migration is one way for people to adapt to these coastal changes, but presents an enormous policy challenge given the number of people affected. Knowledge about the relationship between SLR-related hazards and migration is therefore important to allow for anticipatory policymaking. In recent years, an increasing number of empirical studies have investigated, using survey or census data, how SLR-related hazards including flooding, salinization, and erosion together with non-environmental factors influence migration behavior. In this article, we provide a systematic literature review of this empirical work. Our review findings indicate that flooding is not necessarily associated with increased migration. Severe flood events even tend to decrease long-term migration in developing countries, although more research is needed to better understand the underpinnings of this finding. Salinization and erosion do generally lead to migration, but the number of studies is sparse. Several non-environmental factors including wealth and place attachment influence migration alongside SLR-related hazards. Based on the review, we propose a research agenda by outlining knowledge gaps and promising avenues for future research on this topic. Promising research avenues include using behavioral experiments to investigate migration behavior under future SLR scenarios, studying migration among other adaptation strategies, and complementing empirical research with dynamic migration modeling. We conclude that more empirical research on the SLR-migration nexus is needed to properly understand and anticipate the complex dynamics of migration under SLR, and to design adequate policy responses. This article is categorized under: Climate Economics < Aggregation Techniques for Impacts and Mitigation CostsVulnerability and Adaptation to Climate Change < Learning from Cases and AnalogiesAssessing Impacts of Climate Change < Evaluating Future Impacts of Climate Change.

In harm's way: Non-migration decisions of people at risk of slow-onset coastal hazards in Bangladesh

Non-migration is an adaptive strategy that has received little attention in environmental migration studies. We explore the leveraging factors of non-migration decisions of communities at risk in coastal Bangladesh, where exposure to both rapid- and slow-onset natural disasters is high. We apply the Protection Motivation Theory (PMT) to empirical data and assess how threat perception and coping appraisal influences migration decisions in farming communities suffering from salinization of cropland. This study consists of data collected through quantitative household surveys (n = 200) and semi-structured interviews from four villages in southwest coastal Bangladesh. Results indicate that most respondents are unwilling to migrate, despite better economic conditions and reduced environmental risk in other locations. Land ownership, social connectedness, and household economic strength are the strongest predictors of non-migration decisions. This study is the first to use the PMT to understand migration-related behaviour and the findings are relevant for policy planning in vulnerable regions where exposure to climate-related risks is high but populations are choosing to remain in place.

A bibliometric review on the drivers of environmental migration

A large body of literature exists arguing that numerous, complex factors result in environmental migration. Thus, in order to understand environmental migration, we must investigate how its drivers are defined, explained and interrelated. This study aims to produce a comprehensive analysis of the literature on the drivers of environmental migration and assess future opportunities for studying 'environmental migration'. We conduct a systematic literature search using the keywords 'environmental migration' and 'drivers' in Scopus and Web of Knowledge, analysing 146 publications. The findings are organised as a bibliometric analysis, including network analysis and evaluation of publication metrics. Results show that the literature on environmental migration drivers constitutes a relatively new, growing field largely developed in the USA. It is rooted in the wider environmental migration literature and strongly associated with the discourse of climate change impacts as driving factors. Typologies of 'migrants' are more prevalent than 'refugees' when referring to actors.

Demographic perspectives in research on global environmental change

The human population is at the centre of research on global environmental change. On the one hand, population dynamics influence the environment and the global climate system through consumption-based carbon emissions. On the other hand, the health and well-being of the population are already being affected by climate change. A knowledge of population dynamics and population heterogeneity is thus fundamental to improving our understanding of how population size, composition, and distribution influence global environmental change and how these changes affect population subgroups differentially by demographic characteristics and spatial distribution. The increasing relevance of demographic research on the topic, coupled with availability of theoretical concepts and advancement in data and computing facilities, has contributed to growing engagement of demographers in this field. In the past 25 years, demographic research has enriched climate change research-with the key contribution being in moving beyond the narrow view that population matters only in terms of population size-by putting a greater emphasis on population composition and distribution, through presenting both empirical evidence and advanced population forecasting to account for demographic and spatial heterogeneity. What remains missing in the literature is research that investigates how global environmental change affects current and future demographic processes and, consequently, population trends. If global environmental change does influence fertility, mortality, and migration, then population estimates and forecasts need to adjust for climate feedback in population projections. Indisputably, this is the area of new research that directly requires expertise in population science and contribution from demographers.

What Drives Migration to Europe? Survey Experimental Evidence from Lebanon

What drives people to migrate? Amid a stark increase in international migration at the global scale, we lack individual-level evidence that causally adjudicates between migration’s many drivers. We implement a survey experiment in Northern Lebanon—a hotbed of international migration—to a random sample of 1,000 Syrian refugees and 1,000 Lebanese residents. Respondents were shown the profile of a hypothetical Syrian refugee and asked whether they recommended that the refugee migrate to the European Union. The vignette randomly primed five prominent causes of migration, including push factors (political instability and poverty) and pull factors (open borders, employment opportunities, and cultural openness). We find that pull factors outweighed push factors, suggesting that migrants carefully weigh their chances in Europe. Still, all five primes yielded positive effect sizes, which underlines that prominent theories of migration are complements, not substitutes. Taken together, the evidence suggests that empirical models of migration can be improved if they take into consideration both pull and push factors, rather than prioritizing one over the other.

Pregnancy outcomes among evacuees of the Sinabung volcano, 2010-2018 (North Sumatra, Indonesia): A matched cohort study

OBJECTIVES

Exposure to natural disasters during pregnancy is associated with adverse birth outcomes and increased probability of female births. Nonetheless, relatively little work has been done on evacuations of women living in close vicinity to volcanic eruptions. We conducted a retrospective cohort study among women from villages near the Sinabung volcano in North Sumatra, Indonesia, which has been active since 2010.

METHODS

We compared an "exposed" sample of women (n = 97) who were pregnant when forced to evacuate their villages due to the volcanic eruptions and an "unexposed" sample of non-evacuees (n = 97) matched for age and year of child's birth. We collected anthropometric data (height and weight of each woman) and conducted structured interviews about pregnancy outcomes and evacuation-related stress.

RESULTS

Evacuation led to an almost five-fold increase in the adjusted odds of having an early or preterm birth in non-imputed (OR = 4.84, 95% CI: 1.31-17.92) and multiply imputed (OR = 4.84, 95% CI: 1.29-19.19) analyses. It also led to approximately a 1 cm decrease in birth length in the non-imputed (β = -1.10, 95% CI: -1.96-0.24) and multiply imputed (β = -1.17, 95% CI: -1.20-0.36) analyses, both including controls for confounders. We found decreasing birth length with increasing stress among evacuees. There was no discernible effect of evacuation or stress on the other outcomes.

CONCLUSIONS

Both adverse effects we documented can exert negative influences on later-in-life outcomes for children of women pregnant during evacuation. This should be considered when developing protocols for supporting women and connecting them with clinical resources when evacuated from natural disasters.

The form and evolution of international migration networks, 1990-2015

Presently, there is no agreed upon data-driven approach for identifying the geographic boundaries of migration networks that international migration systems are ultimately manifested in. Drawing from research on community detection methods, we introduce and apply the Information Theoretic Community Detection Algorithm for identifying and studying the geographic boundaries of migration networks. Using a new set of estimates of country-to-country migration flows every 5 years from 1990 to 1995 to 2010-2015, we trace the form and evolution of international migration networks over the past 25 years. Consistent with the concept of dynamic stability, we show that the number, size and internal country compositions of international migration networks have been remarkably stable over time; however, we also document many short-term fluctuations. We conclude by reflecting on the spirit of our work in this paper, which is to promote consensus around tools and best practices for identifying and studying international migration networks.

The Differential Influence of Geographic Isolation on Environmental Migration: A Study of Internal Migration Amidst Degrading Conditions in the Central Pacific

This study investigates how geographic isolation interacts with declining environmental and economic conditions in Kiribati, an island nation wherein which limited access to financial resources amidst degrading environmental conditions potentially constrain capital-intensive, long distance migration. We examine whether geographic isolation modifies the tenets of two dominant environmental migration theses. The environmental scarcity thesis suggests that environmental degradation prompts migration by urging households to reallocate labor to new environments. In contrast, the environmental capital thesis asserts that declining natural resource availability restricts capital necessary for migration. Results show that the commonly applied environmental scarcity thesis is less valid and the environmental capital thesis is more relevant in geographically isolated places. Findings indicate that geographic isolation is an important dimension along which migration differences emerge. As overall environmental and economic conditions worsen, likelihoods of out-migration from less remote islands increase whereas likelihoods of out-migration from more isolated islands decrease.

Climate exposures and child undernutrition: Evidence from Indonesia

Global climate change has the potential to disrupt agricultural systems, undermine household socioeconomic status, and shape the prevalence and distribution of diseases. Each of these changes may influence children's nutritional status, which is sensitive to food availability, access, and utilization, and which may have lasting consequences for later-life health and socioeconomic outcomes. This paper contributes to the emerging literature on climate and child health by studying the effects of temperature and precipitation exposures on children's height and weight in Indonesia. Drawing on five rounds of the Indonesian Family Life Survey (IFLS) implemented between 1993 and 2015, we estimate fixed-effects regression models of height-for-age (HFA) and weight-for-height (WFH) among samples of children ages 24-59 months and 0-23 months, respectively. We test for heterogeneity in these effects across sub-populations expected to vary in their vulnerability. Results show that delays in monsoon onset are consistently associated with worse child health outcomes. Delays in monsoon onset during the prenatal period are associated with reduced child height among children age 2-4 years. The weight of young (<2 years) children is adversely affected by delays in the most recent monsoon season, and this relationship is particularly strong among residents of Java. Overall, our results underline the need for interventions that protect children's nutrition and underlying health against the effects of climate change.

A Critical Analysis of the Drivers of Human Migration Patterns in the Presence of Climate Change: A New Conceptual Model

Both climate change and migration present key concerns for global health progress. Despite this, a transparent method for identifying and understanding the relationship between climate change, migration and other contextual factors remains a knowledge gap. Existing conceptual models are useful in understanding the complexities of climate migration, but provide varying degrees of applicability to quantitative studies, resulting in non-homogenous transferability of knowledge in this important area. This paper attempts to provide a critical review of climate migration literature, as well as presenting a new conceptual model for the identification of the drivers of migration in the context of climate change. It focuses on the interactions and the dynamics of drivers over time, space and society. Through systematic, pan-disciplinary and homogenous application of theory to different geographical contexts, we aim to improve understanding of the impacts of climate change on migration. A brief case study of Malawi is provided to demonstrate how this global conceptual model can be applied into local contextual scenarios. In doing so, we hope to provide insights that help in the more homogenous applications of conceptual frameworks for this area and more generally.

Health Status and Health Care Needs of Drought-Related Migrants in the Horn of Africa-A Qualitative Investigation

Somalia, Kenya and Ethiopia, situated in the Horn of Africa, are highly vulnerable to climate change, which manifests itself through increasing temperatures, erratic rains and prolonged droughts. Millions of people have to flee from droughts or floods either as cross-border refugees or as internally displaced persons (IDPs). The aim of this study was to identify knowledge status and gaps regarding public health consequences of large-scale displacement in these countries. After a scoping review, we conducted qualitative in-depth interviews during 2018 with 39 stakeholders from different disciplines and agencies in these three countries. A validation workshop was held with a selection of 13 interviewees and four project partners. Malnutrition and a lack of vaccination of displaced people are well-known challenges, while mental health problems and gender-based violence (GBV) are less visible to stakeholders. In particular, the needs of IDPs are not well understood. The treatment of mental health and GBV is insufficient, and IDPs have inadequate access to essential health services in refugee camps. Needs assessment and program evaluations with a patients’ perspective are either lacking or inadequate in most situations. The Horn of Africa is facing chronic food insecurity, poor population health and mass displacement. IDPs are an underserved group, and mental health services are lacking. A development approach is necessary that moves beyond emergency responses to the building of long-term resilience, the provision of livelihood support and protection to reduce displacement by droughts.

Domestic migration and mobile phones: A qualitative case study focused on recent migrants to Ouagadougou, Burkina Faso

Migration has long been used as a strategy for livelihood diversification in rural, subsistence communities. Yet in order for migration to effectively serve as a livelihood diversification strategy, it should meet certain conditions: migration should ease financial burdens, should confer access to economically valuable resources and information, and should broaden social networks. Using qualitative data gathered in 25 interviews with rural migrants to Ouagadougou, Burkina Faso, we examine how mobile phone technology has impacted migration as a livelihood diversification strategy. Our results show that while mobile phones facilitate migration, the advantages conferred may benefit migrants at the expense of the home communities. Mobile phones alleviate financial constraints, enable access to broader networks, and facilitate informational and resource support among migrants. Our results show limited evidence of migrants using mobile phone technology to provide resources or information to the home community. Our results highlight the need to reconsider the ways in which migration can be used as a livelihood diversification strategy in light of changing communication technologies to promote the economic success of both migrants and their home communities.

Trapped or Voluntary? Non-Migration Despite Climate Risks

Millions of people impacted by climate change actually want to remain in place; these aspirations and respective capabilities need more attention in migration research and climate adaptation policies. Residents at risk may voluntarily stay put, as opposed to being involuntarily trapped, and understanding such subjectivity is empirically challenging. This comment elaborates on “voluntary non-migration” to call attention to a neglected population within the ongoing discourses on climate-induced migration, social equality and human rights. A roadmap for action outlines specific research and policy goals.

Climate anomalies, land degradation and rural out-migration in Uganda

Globally, rural livelihoods are increasingly challenged by the dual threats of land degradation and climate change. These issues are of particular concern in sub-Saharan Africa, where land degradation is believed to be severe and where climate change will bring higher temperatures and shifts in rainfall. To date, however, we know little about the relative effects of these various potential environmental stressors on migration. To examine these processes, we link longitudinal data from 850 Ugandan households with environmental data on soils, forests, and climate, and then analyze these data using approaches that account for potential spatial and temporal confounders. Our findings reveal that climate anomalies, rather than land degradation, are the primary contributor to environmental migration in Uganda, with heat stress of particular importance. Short hot spells increase temporary migration, an element of a diversified household livelihood strategy, while long-term heat stress induces permanent migration through an agricultural livelihoods pathway.

Evacuees and Migrants Exhibit Different Migration Systems After the Great East Japan Earthquake and Tsunami

Research on the destinations of environmentally induced migrants has found simultaneous migration to both nearby and long-distance destinations, most likely caused by the comingling of evacuee and permanent migrant data. Using a unique data set of separate evacuee and migration destinations, we compare and contrast the pre-, peri-, and post-disaster migration systems of permanent migrants and temporary evacuees of the Great East Japan Earthquake and Tsunami. We construct and compare prefecture-to-prefecture migration matrices for Japanese prefectures to investigate the similarity of migration systems. We find evidence supporting the presence of two separate migration systems-one for evacuees, who seem to emphasize short distance migration, and one for more permanent migrants, who emphasize migration to destinations with preexisting ties. Additionally, our results show that permanent migration in the peri- and post-periods is largely identical to the preexisting migration system. Our results demonstrate stability in migration systems concerning migration after a major environmental event.

Internal Migration in the United States: A Comprehensive Comparative Assessment of the Consumer Credit Panel

BACKGROUND

We introduce and provide the first comprehensive comparative assessment of the Federal Reserve Bank of New York/Equifax Consumer Credit Panel (CCP) as a valuable and underutilized dataset for studying internal migration within the United States. Relative to other data sources on US internal migration, the CCP permits highly detailed cross-sectional and longitudinal analyses of migration, both temporally and geographically.

OBJECTIVE

We seek to demonstrate the comparative utility and some of the unique advantages of the CCP relative to other data sources on US internal migration.

METHODS

We compare cross-sectional and longitudinal estimates of migration from the CCP to similar estimates derived from the American Community Survey, the Current Population Survey, Internal Revenue Service data, the National Longitudinal Survey of Youth, the Panel Study of Income Dynamics, and the Survey of Income and Program Participation.

RESULTS

Our results firmly establish the comparative utility and clearly illustrate some of the unique advantages of the CCP relative to other data sources on US internal migration.

CONCLUSIONS

We conclude by identifying some profitable directions for future research on US internal migration using the CCP, as well as reminding readers of the strengths and limitations of these data.

CONTRIBUTION

We provide an introduction to the CCP as a comprehensive comparative point of reference to stimulate future research on US internal migration using these data. More broadly, this paper contributes to research on the use of non-traditional data sources to study migration given well-documented problems with the availability, quality, and comparability of migration data from traditional sources.

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

In popular accounts, stories of environmental refugees convey a bleak picture of the impacts of climate change on migration. Scholarly research is less conclusive, with studies finding varying effects. This paper uses an agent-based model (ABM) of land use, social networks, and household dynamics to examine how extreme floods and droughts affect migration in Northeast Thailand. The ABM explicitly models the dynamic and interactive pathways through which climate-migration relationships might operate, including coupled out and return streams. Results suggest minimal effects on out-migration but marked negative effects on return. Social networks play a pivotal role in producing these patterns. In all, the portrait of climate change and migration painted by focusing only on environmental refugees is too simple. Climate change operates on already established migration processes that are part and parcel of the life course, embedded in dynamic social networks, and incorporated in larger interactive systems where out- and return migration are integrally connected.

Spatial and Temporal Dimensions of Weather Shocks and Migration in Nepal

Research shows that environmental shocks can influence migration. However, studies vary widely in the shocks and type of migration measured, the context, and the strength and direction of environmental effects. In addition, existing theories provide opposing predictions for this relationship. There is a clear need for further theoretical development in the climate-migration literature. This study, in rural Nepal, examines four types of weather shocks, over various time frames, on four types of migration. Results suggest that the most substantial influence of weather shocks is not in a wholesale increase or decrease in migration. Instead, weather shocks are related to changes in the type of migration used, resulting in less long-term and more short-term migrations in the population. We use the Ready-Willing-and-Able perspective to make sense of these patterns.

Usable Science for Managing the Risks of Sea-Level Rise

Sea-level rise sits at the frontier of usable climate climate change research, because it involves natural and human systems with long lags, irreversible losses, and deep uncertainty. For example, many of the measures to adapt to sea-level rise involve infrastructure and land-use decisions, which can have multigenerational lifetimes and will further influence responses in both natural and human systems. Thus, sea-level science has increasingly grappled with the implications of (1) deep uncertainty in future climate system projections, particularly of human emissions and ice sheet dynamics; (2) the overlay of slow trends and high-frequency variability (e.g., tides and storms) that give rise to many of the most relevant impacts; (3) the effects of changing sea level on the physical exposure and vulnerability of ecological and socioeconomic systems; and (4) the challenges of engaging stakeholder communities with the scientific process in a way that genuinely increases the utility of the science for adaptation decision making. Much fundamental climate system research remains to be done, but many of the most critical issues sit at the intersection of natural sciences, social sciences, engineering, decision science, and political economy. Addressing these issues demands a better understanding of the coupled interactions of mean and extreme sea levels, coastal geomorphology, economics, and migration; decision-first approaches that identify and focus research upon those scientific uncertainties most relevant to concrete adaptation choices; and a political economy that allows usable science to become used science.

The Influence of Environmental Change (Crops and Water) on Population Redistribution in Mexico and Ethiopia

This paper discusses the effects of long-term environmental change (represented by the abundance or scarcity relative to the long-term average level of crop yield/river flow) and short-term environmental shock (represented by the maximum number of consecutive years below the median crop yield/river flow per decade) on population redistribution in Mexico and Ethiopia. Crop production and water resources, which are affected by climate change and influence human survival and activities, were selected as research variables. Two developing countries, namely, Mexico and Ethiopia, were selected as comparison cases. The results showed that short-term environmental shocks had no correlation with population redistribution. Short-term environmental shocks might fail to influence migration decisions or cause only temporary displacements that cannot be detected by demographic statistics. Among the long-term environmental change factors, only crop yield deviation was found to have a significant positive correlation with population redistribution. Based on two different datasets and two different decades, crop yield deviation is positively correlated with population redistribution; the correlation coefficients between crop yield deviation and population redistribution were 0.134 to 0.162 in Mexico and 0.102 to 0.235 in Ethiopia. When urbanization was considered as the control variable, the correlation coefficient between crop yield deviation and population redistribution in Mexico dropped by half, while it was almost the same in Ethiopia. However, Ethiopia’s population redistribution was more clearly influenced by the population itself. Crop yield deviation relative to water flow deviation meant changes in livelihoods. Population redistribution is a possible means of adapting to changes in livelihood. Mexico exhibited high resilience to changes in livelihoods caused by long-term environmental change, especially in its densely populated areas. In contrast, Ethiopia was characterized mainly by high population growth and low population migration. People in some areas of Ethiopia were forced to endure hardship of livelihood deterioration or to stay where they were due to the difficulty of obtaining sufficient resources to afford the cost of migration.