2011年-世界发展银行全球_The_Cost_of_Adapting_to_Extreme_Weather_Events_in_a_Changing_Climate_64页_2mb

Summary of The Cost of Adapting to Extreme Weather Events in a Changing Climate (Bangladesh)

Core Content

This report, published by the World Bank in 2011, focuses on the cost of adapting to extreme weather events—specifically inland monsoon floods and cyclones and storm surges—in Bangladesh, a country highly vulnerable to climate change impacts. The study is part of the Economics of Adaptation to Climate Change (EACC) program and aims to estimate the costs of climate-proofing infrastructure and protecting populations from increased flood and storm surge risks by 2050.

Main Points

• Bangladesh's Climate Vulnerability:

  • The country is located in the delta of the Ganges, Brahmaputra, and Meghna (GBM) rivers, making it prone to river and rainwater floods, cyclones, and storm surges.
  • Two-thirds of the country's land area is less than 5 m above sea level, increasing exposure to tidal flooding and coastal hazards.
  • The population is expected to grow from 150 million to 230 million by 2050, raising the stakes of climate adaptation.

• Climate Change Impacts:

  • Temperature rise of 1–3°C and 20% more monsoon rainfall by 2050 are projected for the GBM basin.
  • Sea-level rise and increased ocean temperatures are expected to intensify cyclones, with storm surges potentially covering an additional 15% of coastal areas.
  • Inundation depths and flood-affected areas are expected to increase, leading to greater risks for both people and infrastructure.

• Historical Context:

  • Since 1954, Bangladesh has experienced 21 above-normal floods, 4 exceptional, and 2 catastrophic.
  • The 2007 flood, with a 90-year return period, affected 42% of the country, 14 million people, and caused $1.1 billion in asset losses.

• Adaptation Needs:

  • The baseline scenario (without climate change) predicts 45% of land will be flooded to 0.3 m depth.
  • Under the climate change scenario, the flooded area is expected to increase by 4%, and inundation depths will rise.
  • Cyclonic storm surges will cover more coastal area, with inundation depths potentially reaching 2 m.

Key Information

Inland Monsoon Floods

• Total adaptation cost by 2050: $3.3 billion.
• Cost Breakdown:
  • Road height enhancement: $2.72 billion (83% of total).
  • Road cross-drainage: $50 million.
  • Railway height enhancement: $27 million.
  • River embankment enhancement: $96 million.
  • Coastal polder cross-drainage: $421 million.
• Population at Risk:
  • 2001: 23 million people in rural areas at risk of >0.3 m inundation.
  • 2050: 19.2 million rural people at risk due to urban migration, but 1.9 million additional lives will be affected due to increased flood areas.

Cyclones and Storm Surges

• Total adaptation cost by 2050: $2.4 billion.
• Cost Breakdown:
  • Polder height enhancement: $892 million.
  • Multipurpose cyclone shelters: $1.2 billion.
  • Cyclone-resistant private housing: $200 million.
  • Coastal afforestation: $75 million.
  • Early warning system strengthening: $39 million.
• Annual recurrent cost: Over $50 million.
• Population at Risk:
  • Baseline scenario: 8 million people at risk of >1 m inundation.
  • Climate change scenario: 17 million people at risk of >1 m, and 13.5 million at risk of >3 m.

Adaptation and Investment Planning

• Total estimated adaptation cost for both hazards by 2050: $5.7 billion.
• Recommendations:
  • Prioritize existing risks and current infrastructure needs.
  • Use GIS-based analysis to identify vulnerable populations and infrastructure.
  • Sequence adaptation actions due to the uncertainty of climate change impacts.
  • Combine "hard" infrastructure investments with "soft" measures such as education and job training to reduce vulnerability to climate-induced resource loss.
  • Ensure efficient institutional arrangements and sound public policies for effective implementation of adaptation measures.

Conclusion

The study highlights the urgent need for adaptation in Bangladesh to mitigate the increased risks from extreme weather events. It provides detailed cost estimates and population vulnerability data to guide investment planning and policy formulation. The findings emphasize the importance of climate-smart infrastructure and community-based early warning systems in building resilience against future climate impacts.