Population and Environment最新文献

In recent decades, the possibility that climate change will lead to depopulation of vulnerable areas in the global tropics via migration, mortality, or collapsing fertility has generated significant concern. We address this issue by using data on subnational population growth from 1,809 subnational units across the global tropics and linked data on climate exposures to examine how decadal temperature and precipitation anomalies influence population-weighted intercensal growth rates. Our fixed effects regression analysis reveals that the lowest predicted population growth rates occur under hot and dry conditions. The effects of heat and drought are strongest in districts that, at baseline, have high population densities, high precipitation rates, or high educational attainment. These patterns are contrary to common assumptions about these processes, and even the rare combination of hot and dry conditions, occurring in less than 7% of our sample, does not lead to local depopulation. Taken together with previous findings, this suggests that depopulation narratives do not have a strong evidentiary basis.

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.

Rural populations are particularly exposed to increasing weather variability, notably through agriculture. In this paper, we exploit longitudinal data for Turkish provinces from 2008 to 2018 together with precipitation records over more than 30 years to quantify how variability in a standardized precipitation index (SPI) affects out-migration as an adaptation mechanism. Doing so, we document the role of three potential causal channels: per capita income, agricultural output, and local conflicts. Our results show that negative SPI shocks (droughts) are associated with higher out-migration in rural provinces. A mediated-moderator approach further suggests that changes in per capita income account for more than one quarter of the direct effect of droughts on out-migration, whereas agricultural output is only relevant for provinces in the upper quartile of crop production. Finally, we find evidence that local conflict fatalities increase with drought and trigger out-migration, although this channel is distinct from the direct effect of SPI shocks on out-migration.

Between 1960 and 2011, world population grew from 3 to 7 billion, an unprecedented rate of population growth that will never be seen again. In spite of the addition of 4 billion people in just 51 years, the world experienced some of the biggest improvements in living standards in human history, with declines in poverty and improvements in food production per capita in all major regions. This paper looks at the period since 2011, during which the world added another billion people. Progress has continued in many areas, with food production continuing to grow faster than population and with continued declines in the proportion of the population in poverty in all regions. Not all trends are positive, however. Progress in food production has slowed, with recent declines in food production per capita in Africa. Prices of food and other commodities have recently hit historic highs. Climate change is a challenge to progress in combatting hunger and poverty, especially in Africa. While climate change will make it harder to meet the needs of Africa's continued population growth in this century, the paper shows that the countries with the highest population growth account for a very small share of global CO₂ emissions. The record of the last six decades suggests that progress can be made to reduce poverty and hunger, even while world population continues to grow, but continued progress will require solutions to climate change that mainly target high-income and middle-income countries.