2017年-世界发展银行全球_Greening_Africas_Cities___Enhancing_the_Relationship_between_Urbanization_Environmental_Assets_and_Ecosystem_Services_56页_4mb

Summary of "Greening Africa's Cities: Enhancing the relationship between urbanization, environmental assets and ecosystem services"

Core Content

This report explores the complex relationship between urbanization, environmental assets, and ecosystem services in African cities. It highlights the challenges and opportunities associated with integrating environmental considerations into urban development, emphasizing the need for sustainable and green urban planning.

Main Points

Urbanization in Africa

• Late but rapid urbanization: Africa's urbanization started later than other regions and is currently at around 40% urbanization rate, making it the least urbanized region globally. However, this is changing quickly, with SSA cities projected to grow at 2.5-3.5% annually from 2015 to 2055.
• Implications for the environment: While most urban areas have not yet developed, the rapid growth is putting increasing pressure on natural ecosystems. The natural capital and biodiversity are at risk due to the expansion of the built environment.

Environmental Impacts of Urbanization

• Three types of urban activities affecting the environment:
  • Expanded use and consumption of natural resources.
  • Transformation of natural environments into built environments.
  • Generation of waste, including atmospheric emissions, wastewater, and solid waste.
• These activities interact in complex ways and have mutually compounding effects on the natural environment.

Economic, Fiscal and Social Costs

• The degradation of natural assets and ecosystems has tangible economic, fiscal, and social costs.
• These include increased water production costs, deteriorating human health, damage to infrastructure, and reduced property and recreational values.
• There is a significant risk of cities becoming locked into a "grow dirty now, clean up later" trajectory, which is potentially costly and inefficient.

Green Urban Development

• Green urban development is a strategy that can help cities move from negative (B or C) to positive (A) environmental trajectories.
• It involves understanding the nature of urbanization and implementing appropriate measures to enhance the built environment's relationship with the natural environment.
• The report provides a toolkit of policy measures, instruments, and planning strategies that can be adapted and utilized by city and national governments.

Key Characteristics of Africa's Urbanization

• Late but rapid urbanization: Africa is urbanizing later than other regions, but at a faster pace. This leads to a unique set of challenges for the natural environment.
• Low levels of wealth, fiscal resources, and service delivery: African cities are developing with limited financial and institutional resources, resulting in inadequate infrastructure and services.
• Low levels of industrialization, motorization, and technology: This affects the types of environmental pressures faced by African cities.
• Weak institutions and systems: This limits the ability of cities to manage environmental assets and implement effective policies.

Case Study: Nakivubo Wetland in Kampala

• The Nakivubo wetland is a crucial natural asset that has been severely degraded due to urban expansion and pollution.
• It provides important ecosystem services, including water treatment and recreation.
• A "treatment train" of interventions was identified to restore the wetland, including improved sanitation, wastewater treatment, wetland rehabilitation, and investment in recreational facilities.
• The estimated initial cost is US$53 million, with annual maintenance costs of US$3.6 million.
• The project could yield water treatment cost savings of US$1 million per year and recreational benefits exceeding US$22 million per year.
• The net present value over 15 years is estimated to be between -US$24 million and US$220 million, with an internal rate of return ranging from 4% to 34%.
• Despite the potential benefits, the high initial costs and political challenges may hinder the implementation of such projects.

Conclusion

• The report underscores the importance of addressing environmental, economic, and fiscal challenges in African cities through targeted green urban development strategies.
• Proactive intervention is necessary to prevent irreversible damage to natural assets and to ensure that cities can maintain a sustainable balance between their natural and built environments.
• Strengthening institutions, securing targeted finance, and adopting a green urban planning paradigm are critical to achieving this goal.

Key Information

• Scope: The report is based on eight research exercises conducted between 2015 and 2017.
• Methodology: Includes regional desk studies, urban environmental profiles, ecosystem services valuation, and a policy toolkit.
• Key Findings:
  • Urbanization has significant negative environmental impacts.
  • Green urban development can reverse these trends and improve both environmental and economic outcomes.
  • Institutional and financial barriers need to be addressed to enable effective environmental management in African cities.

References

• The report draws on the methodologies of TEEB (The Economics of Ecosystems and Biodiversity) and includes insights from various researchers and stakeholders involved in the study.