2014年-世界发展银行全球_50_Years_of_Urbanization_in_Africa___Examining_the_Role_of_Climate_Change_44页_2mb

50 Years of Urbanization in Africa: Examining the Role of Climate Change

Core Content

This working paper investigates the relationship between climate change and urbanization in Sub-Saharan Africa over the past 50 years. The authors, J. Vernon Henderson, Adam Storeygard, and Uwe Deichmann, analyze how changes in moisture availability influence migration patterns and urban economic development.

Main Points

• Climate Impact on Migration: Climate variation, particularly reduced moisture availability, has a significant impact on urbanization in Africa. In more arid countries, lower moisture levels reduce farm incomes, leading to increased migration to nearby cities. Conversely, wetter conditions slow migration.

• Rural-Urban Income Links: The paper highlights the connection between rural and urban incomes. In countries with a larger industrial base, reduced moisture shrinks the agricultural sector and increases urban incomes. However, in regions where cities are entirely dependent on agricultural services, reduced moisture tends to lower urban incomes.

• Occupational Shifts in Rural Areas: Climate changes also influence occupational choices within the rural sector. Drier conditions lead to a shift away from farm activities, especially for women, into non-farm activities or out of the workforce. Increased moisture raises the probability of working in agriculture, particularly for women, by about 7%, and for men by about 3.4%, with corresponding declines in off-farm work.

• Theoretical Model: The authors develop a model that considers the effects of moisture changes on both the urban and rural sectors. The model shows that urbanization and city income are affected by the presence of an export-oriented manufacturing sector and the nature of the local urban economy.

• Empirical Evidence: Using data on nighttime urban lights as a proxy for income, the study finds that decreased moisture leads to increased total city income in areas with an export manufacturing base. However, in areas where cities only serve agriculture, the effect is minimal or ambiguous.

• Future Climate Projections: The paper notes that future climate change is expected to worsen agricultural conditions in many parts of Africa, especially in coastal West Africa and Southern Africa. This is likely to increase urbanization, with more significant impacts on less industrialized regions.

Key Information

• Methodology: The study uses a 50-year panel of 369 districts across 29 African countries. It focuses on local urbanization and analyzes how changes in moisture affect population distribution and economic outcomes.

• Data Sources: The authors use actual census data rather than interpolated data, which improves the accuracy of their findings. They also incorporate data from the Demographic and Health Surveys (DHS) to examine individual-level labor market responses.

• Economic Model: The model distinguishes between two scenarios:

  • When cities have an export-oriented manufacturing sector, reduced moisture increases urban population and total city income.
  • When cities are only dependent on local agricultural services, the effect of reduced moisture is ambiguous and may lead to a decline in urban incomes.

• Policy Implications: The findings suggest that climate change will have a significant impact on urbanization and economic development in Africa. Cities with more industrial activity are likely to benefit from reduced moisture, while those dependent solely on agriculture may suffer.

Conclusion

The paper concludes that there is a strong link between climate and urbanization in Africa. As climate change continues, especially with further drying in some regions, the urbanization process will be influenced by the structure of the local economy. The authors emphasize the need for policies that support adaptation and economic diversification to mitigate the negative impacts of climate change on rural and urban populations.