Temperature anomalies undermine the health of reproductive-age women in low- and middle-income countries.

Climate change is expected to undermine population health and well-being in low- and middle-income countries, but relatively few analyses have directly examined these effects using individual-level data at global scales, particularly for reproductive-age women. To address this lacuna, we harmonize nationally representative data from the Demographic and Health Surveys on reproductive health, body mass index (BMI), and temporary migration from 2.5 million adult women (ages 15 to 49) in approximately 109,000 sites across 59 low- and middle-income countries, which we link to high-resolution climate data. We use this linked dataset to estimate fixed-effect logistic regression models of demographic and health outcomes as a function of climate exposures, woman-level and site-level characteristics, seasonality, and regional time trends, allowing us to plausibly isolate climate effects from other influences on health and migration. Specifically, we measure the effects of recent exposures to temperature and precipitation anomalies on the likelihood of having a live birth in the past year, desire for another child, use of modern contraception, underweight (BMI < 18.5), and temporary migration, and subsequently allow for nonlinearity as well as heterogeneity across education, rural/urban residence, and baseline climate. This analysis reveals that exposures to high temperatures increase live births, reduce desire for another child, increase underweight, and increase temporary migration, particularly in rural areas. The findings represent clear evidence that anthropogenic temperature increases contribute to temporary migration and are a significant threat to women's health and reproductive autonomy in low- and middle-income countries.

"Measuring the Environmental Context of Child Growth in Burkina Faso".

Child growth failure, as indicated by low height-for-age z-scores (HAZ), is an important metric of health, social inequality, and food insecurity. Understanding the environmental pathways to this outcome can provide insight into how to prevent it. While other studies have examined the environmental determinants of HAZ, there is no agreed upon best-practices approach to measure the environmental context of this outcome. From this literature, we derive a large set of potential environmental predictors and specifications including temperature and precipitation levels, anomalies, and counts as well as vegetation anomalies and trends, which we include using linear, nonlinear, and interactive specifications. We compare these measures and specifications using four rounds of DHS survey data from Burkina Faso and a large set of fixed effects regression models, focusing on exposures from the time of conception through the second year of life and relying on joint hypothesis tests and goodness-of-fit measures to determine which approach best explains HAZ. Our analysis reveals that nonlinear and interactive transformations of climate anomalies, as opposed to climate levels or vegetation indices, provide the best explanation of child growth failure. These results underline the complex and nonlinear pathways through which climate change affects child health and should motivate climate-health researchers to more broadly adopt measures and specifications that capture these pathways.

Climate change and educational attainment in the global tropics.

Climate change may negatively impact education among children via exposure to extreme temperature and precipitation conditions. We link census data from 29 countries across the global tropics to high-resolution gridded climate data to understand how climatic conditions experienced in utero and during early childhood affect educational attainment at ages 12 to 16. We show that exposure to higher-than-average temperatures during the prenatal and early-life period is associated with fewer years of schooling in Southeast Asia. In this region, a child who experiences temperatures 2 SDs above average is predicted to attain 1.5 fewer years of schooling than one who experiences average temperatures. In addition, early-life rainfall is positively correlated with attainment in West and Central Africa as well as Southeast Asia, and negatively correlated with attainment in Central America and the Caribbean. While we expected that children from the most educated households would be buffered from these effects, we discover that they tend to experience the greatest educational penalties when exposed to hotter early-life conditions and, in some regions, to drier conditions. For example, among the most educated households in West and Central Africa, predicted schooling is 1.8 years lower for children who experience early-life rainfall 2 SDs below average versus 2 SDs above average, while the difference is just 0.8 years for children from the least educated households. These results suggest that development and educational gains in the tropics could be undermined by climate change, even for better-off households.

Climatic conditions and household food security: Evidence from Tanzania.

Food security and adequate nutrition are critical for achieving progress toward sustainable development. Two billion people worldwide experience moderate to severe food insecurity, and rates of hunger have increased over the past several years after declining steadily for decades. The FAO attributes this increase in large part to climate change, though empirical evidence on the relationship between climatic conditions and food security remains limited. We examine this question by linking nationally representative longitudinal data from four rounds of the Tanzania National Panel Survey to high-resolution gridded climate data. We then estimate a set of fixed effects regression models to understand the linkages between recent rainy season precipitation and temperature and two indicators of household food security: Food Consumption Score (FCS) and reduced Coping Strategies Index (rCSI). We find that low rainfall-particularly dry and cool conditions-is negatively associated with food security. Moving from a typical rainfall year to a particularly dry one increases the risk of being food insecure on both measures simultaneously by 13-percentage points. This suggests that a lack of rainfall impedes households' ability to access food, likely through reduced agricultural production and increased food prices, leading to lower dietary diversity and food shortages. Vulnerability is higher among households with fewer working age members, suggesting that households with a greater supply of labor can better withstand droughts. As climate change alters precipitation and temperature patterns over the coming decades, policies to increase resilience will be critical for improving food security, particularly among populations heavily reliant on agriculture.

Climate change, social vulnerability and child nutrition in South Asia.

Despite recent advancements in global population well-being and food security, climate change threatens to undermine child nutritional health, particularly for marginalized populations in tropical low- and middle-income countries. South Asia is at particular risk for climate-driven undernutrition due to a combination of historical weather exposures, existing nutritional deficits, and a lack of sanitation access. Previous studies have established that precipitation extremes increase rates of undernutrition in this region, but the existing literature lacks adequate consideration of temperature anomalies, mediating social factors, and the developmentally-relevant timing of exposure. We combine high-resolution temperature and precipitation data with large-sample survey data on household demographics and child anthropometry, using an approach that incorporates three key developmental periods and a rigorous fixed effects design. We find that precipitation extremes in the first year of life significantly decrease children's height-for-age (HAZ) in South Asia. The detrimental effects of extreme precipitation are especially concentrated in under-resourced households, such as those lacking access to proper sanitation and education for women, while anomalous heat is particularly harmful for children in Pakistan, though it tends to benefit children in some demographic groups. These results indicate that nutritional status in South Asia is highly responsive to climate exposures, and that addressing sanitation infrastructure and other development priorities is a pathway towards reducing this vulnerability.

Climate anomalies and childhood growth in Peru.

Climate change has been linked to poor childhood growth and development through maternal stress, nutritional insults related to lean harvests, and exposure to infectious diseases. Vulnerable populations are often most susceptible to these stressors. This study tested whether susceptibility to linear growth faltering is higher among Peruvian children from indigenous, rural, low-education, and low-income households. High-resolution weather and household survey data from Demographic and Health Survey 1996-2012 were used to explore height-for-age z-scores (HAZ) at each year of life from 0 to 5. Rural, indigenous children at age 0-1 experience a HAZ reduction of 0.35 units associated with prenatal excess rainfall which is also observed at age 4-5. Urban, non-indigenous children at age 4-5 experience a HAZ increase of 0.07 units associated with postnatal excess rainfall, but this advantage is not seen among rural, indigenous children. These findings highlight the need to consider developmental stage and social predictors as key components in public health interventions targeting increased climate change resilience.

Stability and Change within Indigenous Land Use in the Ecuadorian Amazon.

In the Amazon basin and other tropical forest regions, many forested landscapes are inhabited by indigenous peoples who are increasingly exposed to infrastructure expansion, large-scale natural resource extraction, and development programs. How indigenous land use evolves in this context will be a critical determinant of the future of these forests. To date, few studies have had access to longitudinal, large-sample and field-based data that enables the measurement of indigenous land use change and its correlates in these contexts. To address this lacuna, we make use of a unique multi-ethnic household survey conducted in 32 indigenous communities of the Northern Ecuadorian Amazon in 2001 and again with the same households in 2012. We analyze these data to measure land use and land use change as well as their determinants. This reveals that the overall household agropastoral footprint has remained close to constant over time, but with important changes within particular land uses and ethnicities. Notably, cacao has largely replaced coffee (tracking commodity price changes), and Kichwa and Shuar households have intensified production on increasingly subdivided plots, with the Shuar specializing in cattle. In contrast, Waorani and Cofán households have maintained small footprints, while Secoya households largely abandoned cattle ranching. Taken together, the results emphasize ethnic heterogeneity in indigenous land use change, a pattern which is only visible through the use of a longitudinal, large-sample, field-based design.

Climate-Induced Migration and Unemployment in Middle-Income Africa.

One of the major unresolved questions in the study of vulnerability to climate change is how human migration will respond in low and middle-income countries. The present study directly addresses this lacuna by using census data on migration from 4 million individuals from three middle-income African countries over a 22-year period. We link these individuals to climate exposures in their origins and estimate climatic effects on migration using a fixed-effects regression model. We show that climate anomalies affect mobility in all three countries. Specifically, mobility declines by 19% with a 1-standard deviation increase in temperature in Botswana. Equivalent changes in precipitation cause declines in migration in Botswana (11%) and Kenya (10%), and increases in migration in Zambia (24%). The mechanisms underlying these effects appear to differ by country. Negative associations between precipitation anomalies, unemployment, and inactivity suggest migration declines may be due to an increased local demand for workers to offset production risk, while migration increases may be indicative of new opportunities in destinations. These country-specific findings highlight the contextually-specific nature of climate-migration relationships, and do not support claims that climate change is widely contributing to urbanization across Africa.

Characterizing the Indigenous Forest Peoples of Latin America: Results from Census Data.

Indigenous populations in Latin America are central to regional and global efforts toward achieving socially and environmentally sustainable development. However, existing demographic research on indigenous forest peoples (IFPs) has many limitations, including a lack of comparable cross-national evidence. We address this gap by linking representative census microdata to satellite-derived tree cover estimates for nine countries in the region. Our analyses describe the demographic and socioeconomic characteristics of IFPs, and draw comparisons with reference groups. Our first goal is to examine within- and between-population variation in the age structure, human capital attainment, and economic status of IFPs. We then analyze patterns of fertility among indigenous forest-dwelling women and comparison groups. Finally, we examine the association between migration patterns and tree cover among indigenous and non-indigenous populations. Findings demonstrate that Latin America's IFPs are materially deprived and characterized by high fertility levels overall. Importantly for sustainable development efforts, we show that non-indigenous forest-dwellers outnumber IFPs by more than eight to one and that IFPs have lower fertility than their non-indigenous counterparts when other characteristics are accounted for. Additionally, we find that most in-migrants to heavily-forested areas are non-indigenous, and that in-migrants tend to settle in areas that are forested but have few indigenous inhabitants. These results provide new cross-national evidence on the state of IFPs in Latin America, and highlight the need to empower these groups in the face of growing social and environmental crises in the region.

Temporary Migration and Climate Variation in Eastern Africa.

Africa is likely to experience warming and increased climate variability by the late 21st century. Climate extremes have been linked to adverse economic outcomes. Hence, adaptation is a key component of the United Nations Framework Convention on Climate Change agreements and development assistance. Effective climate adaptation policy requires an understanding of how temperature and rainfall variability affect migration patterns. Yet, how individuals in developing countries manage climate variation is poorly understood, especially in Africa. Combining high-resolution climate data with panel micro-data on migration, labor participation, and demographics, we employ regression analysis to assess temporary migration responses to local temperature and precipitation anomalies in four East African countries. We find that climate impacts are most pronounced in urban areas, with a standard deviation temperature increase and rainfall decrease leading to respective 10 and 12 percent declines in out-migration relative to mean values. Evidence from other labor market outcomes suggests that urban out-migration is not associated with reduced local employment opportunities. Instead, declines in urban out-migration appear to coincide with negative local climate employment impacts. These results challenge the narrative that temporary out-migration serves as a safety valve during climate extremes and that climate change will most strongly affect out-migration rates from rural areas in developing countries.

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.

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.

Climate Shocks Constrain Human Fertility in Indonesia.

Climate change is likely to induce a large range of household- and individual-level responses, including changes in human fertility behaviors and outcomes. These responses may have important implications for human and economic development and women's empowerment. Drawing on the literature linking climate conditions to rice cultivation in Indonesia, we use longitudinal household survey and high-resolution climate data to explore changes in childbearing intentions, family planning use, and births following community-level climate shocks from 1993 to 2015. We find that fertility intentions increase and family planning use declines in response to delays in monsoon onset occurring within the previous year, particularly for wealthier populations. However, women on farms are significantly more likely to use family planning and less likely to give birth following abnormally high temperatures during the previous five years. We also measure parallel shifts in household well-being as measured by rice, food, and non-food consumption expenditures. Our findings advance the environmental fertility literature by showing that longer duration environmental shocks can have impacts on fertility behaviors and outcomes. Collectively, our results illustrate human fertility responses to climate change in a country vulnerable to its effects, and demonstrate that in some cases, climate shocks can constrain human fertility.

Smallholder responses to climate anomalies in rural Uganda.

Recent research suggests that sub-Saharan Africa will be among the regions most affected by the negative social and biophysical ramifications of climate change. Smallholders are anticipated to respond to rising temperatures and precipitation anomalies through on-farm management strategies and diversification into off-farm activities. Few studies have empirically examined the relationship between climate anomalies and rural livelihoods. Our research explores the impact of climate anomalies on farmers' on and off-farm livelihood strategies, considering both annual and decadal climate exposures, the relationship between on and off-farm livelihoods, and the implications of these livelihood strategies for agricultural productivity. To examine these issues, we link gridded climate data to survey data collected in 120 communities from 850 Ugandan households and 2,000 agricultural plots in 2003 and 2013. We find that smallholder livelihoods are responsive to climate exposure over both short and long time scales. Droughts decrease agricultural productivity in the short term and reduce individual livelihood diversification in the long term. Smallholders cope with higher temperatures in the short term, but in the long run, farmers struggle to adapt to above-average temperatures, which lower agricultural productivity and reduce opportunities for diversification. On and off-farm livelihood strategies also appear to operate in parallel, rather than by substituting for one another. These observations suggest that in order to sustain rural livelihoods, new strategies will be necessary if smallholders are to successfully adapt to climate change.

Heat and Adult Health in China.

Given projected increases in the frequency of precipitation and temperature extremes in China, we examine the extent adults may be vulnerable to climate anomalies. We link nutrition, health, and economic data from the China Health and Nutrition Survey (1989-2011) to gridded climate data to identify which socioeconomic outcomes are particularly susceptible, including adult underweight incidence, body mass index, dietary intake, physical activity, illness, income, and food prices. We find warm temperatures augment the probability of being underweight among adults, with a particularly large impact for the elderly (ages > 60). Extremely dry and warm conditions produce a 3.3-percentage point increase in underweight status for this group. Consequences on nutrition coincide with changes in illness rather than dietary, income or purchasing power shifts. Social protection targeting areas prone to excessive heat may consider supplementing bundles of goods with a suite of health care provisions catering to the elderly.

Disruption, not displacement: Environmental variability and temporary migration in Bangladesh.

Mass migration is one of the most concerning potential outcomes of global climate change. Recent research into environmentally induced migration suggests that relationship is much more complicated than originally posited by the 'environmental refugee' hypothesis. Climate change is likely to increase migration in some cases and reduce it in others, and these movements will more often be temporary and short term than permanent and long term. However, few large-sample studies have examined the evolution of temporary migration under changing environmental conditions. To address this gap, we measure the extent to which temperature, precipitation, and flooding can predict temporary migration in Matlab, Bangladesh. Our analysis incorporates high-frequency demographic surveillance data, a discrete time event history approach, and a range of sociodemographic and contextual controls. This approach reveals that migration declines immediately after flooding but quickly returns to normal. In contrast, optimal precipitation and high temperatures have sustained positive effects on temporary migration that persist over one to two year periods. Building on previous studies of long-term migration, these results challenge the common assumption that flooding, precipitation extremes and high temperatures will consistently increase temporary migration. Instead, our results are consistent with a livelihoods interpretation of environmental migration in which households draw on a range of strategies to cope with environmental variability.

Indigenous migration dynamics in the Ecuadorian Amazon: a longitudinal and hierarchical analysis.

Amazonian indigenous populations are approaching a critical stage in their history in which increasing education and market integration, rapid population growth and degradation of natural resources threaten the survival of their traditions and livelihoods. A topic that has hardly been touched upon in this context is migration and population mobility. We address this by analysing a unique longitudinal dataset from the Ecuadorian Amazon on the spatial mobility of five indigenous groups and mestizo co-residents. Analyses reveal traditional and new forms of population mobility and migrant selectivity, including gendered forms of marriage migration and rural-urban moves driven by education. These results illustrate a dynamic present and an uncertain future for indigenous populations in which rural, natural-resource-based lifeways may well be sustained but with increasing links to urban areas.

Climate and marriage in the Netherlands, 1871-1937.

Environmental factors such as climate variability can place significant constraints on demographic behavior in a range of settings. However, few studies investigate the relationships between demography and climate in historical contexts. Using longitudinal individual-level demographic data from the Historical Sample of the Netherlands (HSN) and climate and economic data from 1871-1937, we examine the effects of climate variability on marriage. This analysis reveals that marriage increases with negative environmental conditions such as cold temperatures, riverine flooding, and high rye prices. These findings are not consistent with a Malthusian narrative of marriage behavior, or with the expectation that environmental constraints were stronger in the historical past.

Climate variability and educational attainment: Evidence from rural Ethiopia.

This paper examines the effects of climate variability on schooling outcomes in rural Ethiopia. Investments in education serve as an important pathway out of poverty, yet reduced agricultural productivity due to droughts or temperature shocks may affect educational attainment if children receive poorer nutrition during early childhood, are required to participate in household income generation during schooling ages, or if households can no longer pay for school-related expenses. We link longitudinal socioeconomic, demographic, and schooling data from the Ethiopian Rural Household Survey to high-resolution gridded climate data to measure exposure to temperature and precipitation relative to historical norms. We then estimate a set of multivariate regression models to understand how climate variability impacts grade attainment and school enrollment. Results indicate that early life climatic conditions - namely milder temperatures during all seasons and greater rainfall during the summer agricultural season - are associated with an increased likelihood of a child having completed any education. In addition, greater summer rainfall during both early life and school ages is associated with having completed any schooling as well as with attending school at the time of the survey. These findings suggest that future climate change may reduce children's school participation in rural Sub-Saharan Africa, slowing progress toward human development goals and poverty alleviation.

Climate Variability and Inter-Provincial Migration in South America, 1970-2011.

We examine the effect of climate variability on human migration in South America. Our analyses draw on over 21 million observations of adults aged 15-40 from 25 censuses conducted in eight South American countries. Addressing limitations associated with methodological diversity among prior studies, we apply a common analytic approach and uniform definitions of migration and climate across all countries. We estimate the effects of climate variability on migration overall and also investigate heterogeneity across sex, age, and socioeconomic groups, across countries, and across historical climate conditions. We also disaggregate migration by the rural/urban status of destination. We find that exposure to monthly temperature shocks has the most consistent effects on migration relative to monthly rainfall shocks and gradual changes in climate over multi-year periods. We also find evidence of heterogeneity across demographic groups and countries. Analyses that disaggregate migration by the rural/urban status of destination suggest that much of the climate-related inter-province migration is directed toward urban areas. Overall, our results underscore the complexity of environment-migration linkages and challenge simplistic narratives that envision a linear and monolithic migratory response to changing climates.