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Sunday, December 5, 2010

Climate Risk in Megacities

The Asian Development Bank (ADB), the Japan International Cooperation Agency (JICA), and the World Bank have completed their work assessing climate change impacts to Asian Megacities. That work, published in the report Climate Risks and Adaptation in Asian Megacities, examines climate risk and potential adaptation responses in the cities of Manila, Ho Chi Minh City, and Bangkok. The following summarizes the major points emerging from the report:

Key Findings

  1. Frequency of extreme events likely to increase. All three coastal megacities are likely to witness increases in temperature and precipitation linked with climate change and variability.
  2. Increase in flood-prone area due to climate change in all three cities. In all three megacities, in 2050, there is an increase in the area likely to be flooded under different climate scenarios compared to a situation without climate change.
  3. Increase in population exposed to flooding. In all three cities, there is likely to be an increase in the number of persons exposed to flooding in 2050 under different climate scenarios compared to a situation without climate change.
  4. Costs of damage likely to be substantial and can range from 2 to 6 percent of regional GDP.
  5. Damage to buildings is an important component of flood-related costs.
  6. Impact on the poor and vulnerable will be substantial, but even better-off communities will be affected by flooding.
  7. Land subsidence is a major problem and can account for a greater share of the damage cost from flooding compared to climate-related factors.


  1. Better management of urban environment and infrastructure will help manage potential climate-related impacts. Analysis carried out in the city case studies show that sound urban environmental management is also good for climate adaptation.
  2. Climate-related risks should be considered as an integral part of city and regional planning. While improved urban environmental management is important, the studies also show that given the additional costs linked with climate change, cities need to make a proactive effort to consider climate related risks as an integral part of urban planning and to do so now.
  3. Targeted, city-specific solutions combining infrastructure investments, zoning, and ecosystem-based strategies are required. Given that cities are characterized by distinct climatic, hydrological, and socioeconomic features—but also that the urban poor in general are more vulnerable to increased flooding due to climate change—targeted, city-specific, and cutting edge approaches to urban adaptation are needed.