Droughts and city growth 

  Some researchers and policymakers posit that climate change should increase city growth and urbanization as rising temperatures make rural livelihoods precarious, while others argue that climate change might trap rural households who cannot afford to migrate because of increasing poverty. Existing empirical evidence on the link between climate and urbanization is inconclusive. This chapter exploits novel data mapping city footprint growth for 7,000 cities in 108 low- to middle-income countries across 23 years to provide new evidence on the relationship between drought and urbanization. Cities experience large and persistent declines in built-up area growth rates after major drought events in cities' hinterlands: after 11 years, cities are 0.7 percent smaller compared to a drought-free counterfactual. I show that fully accounting for dynamic effects is essential to correctly understand the relationship between drought and city growth. Consistent with models that envision a drought-migration poverty trap, the negative effects on urbanization are more pronounced for the poorest, and most agricultural countries.

Rapid population growth and city shape 

  Cities in Sub-Saharan Africa are growing rapidly. The urban population has grown ten-fold in the last 50 years, and is projected to keep increasing. What are the consequences of this rapid population growth for city form? In Africa, urban planning has often failed or lagged behind, leaving cities with inadequate infrastructure. Policymakers and researchers have suggested that the rapidity of the rise in urban population is partly to blame, but quantitative and systematic evidence remains scant. I utilize new high resolution data to examine the relationship between population growth and city form. I find that areas in cities which are built up during periods of faster population growth tend to be less densely built, have lower building heights, and are more likely to be exposed to flooding. In addition, these areas have smaller buildings, and are more informal. Together, my findings suggest that urban population growth helps shape the built environment in Sub-Saharan African cities, inducing lower built-up density and more informality.

Trade and pollution: Evidence from India 

  What happens to pollution when developing countries open their borders to trade? Trade might increase production and thus pollution (the scale effect); shift production towards more or less clean industries (the composition effect); or bring with it new technologies or income growth that increases demand for cleaner production (the technique effect). Empirical evidence on the environmental effects of openness to trade in developing countries remains limited. We study the effects of the 1991 trade liberalization reform on water pollution in rivers in India. At the median reduction in district-level tariff exposure, water pollution subsequently rose by 0.12 standard deviations.