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CLIMATE CHANGE AND GLOBAL DAMAGES FROM
TROPICAL CYCLONES Robert Mendelsohn
Kerry Emanuel
Shun Chonabayashi
Laura Bakkensen
Acknowledgements
• Funding by World Bank-United Nations Global Facility for Disaster Reduction & Recovery
• Report:– Natural Hazards, UnNatural Disasters: The
Economics of Effective Prevention – Apurva Sanghi
Goal of this Study
• Predict how climate change will affect tropical cyclones
• Reflect underlying changes in vulnerability in future periods
• Estimate damage functions for tropical cyclones
• Measure how climate change affects future tropical cyclone damages
Past Climate Results
• IPCC 1996 estimates CC increases US tropical cyclone damages by about 0.02% of GDP and world damages by 0.002% of GWP
• Nordhaus 2010 estimates CC doubles US tropical cyclone damages (0.06% of GDP)
• Narita et al 2007 estimate CC doubles world tropical cyclone damages (0.006% GWP)
Emissions Trajectory
Climate Scenario
Tropical Cyclone Behavior
Vulnerability Projection
Damage Function
Damage Estimate
Integrated Assessment Model
Tropical Cyclone GeneratorTropical Cyclone Generator• Step 1: Seed each ocean basin with a very large
number of weak, randomly located cyclones
• Step 2: Cyclones are assumed to move with the large scale atmospheric flow in which they are embedded, taken from the global climate model
• Step 3: Run a detailed cyclone intensity model for each event, and note how many achieve at least tropical storm strength
• Step 4: Using the small fraction of surviving events, determine storm statistics.
Details: Emanuel et al., Bull. Amer. Meteor. Soc., 2008
Tropical Cyclone Damage Function
Constant Minimum Pressure
Income Populat. Density
US 607.5
(10.39)
-86.3
(9.96)
0.370
(0.45)
0.488
(1.53)
Global 15.17
(22.77)
0.415
(6.44)
-0.21
(3.04)
Baseline Tropical Cyclone Damages
• Current Global Damages: $20 billion/yr (0.03% GWP)
• Future Baseline Damages: $55 billion/yr (0.01% GWP)
• Baseline increases by 2100 because of higher income but not as much as GWP
• Baseline assumes current climate
Estimate Climate Impacts
• Calculate future baseline damages (current climate)
• Calculate future damages with future climate
• Subtract baseline from future damages with future climate to get net climate impact
Climate Change DamagesFrom Tropical Cyclones in 2100
Billion USD/yr/(%GWP)
CNRM ECHAM GFDL MIROC
Minimum
Pressure80.1
(0.15%)
13.9(0.03%)
78.8(0.15%)
41.6(0.08%)
Limitations
• All steps of the integrated assessment are uncertain
• Possible interaction with sea level rise not yet taken into account
• Current analysis at national level- needs finer spatial resolution
• No explicit adaptation
Conclusions-1
• Damages from tropical cyclones almost triple by 2100 from income growth
• Climate change likely to double these damages
• Largest CC impacts felt in US and then China
• Island nations will have largest CC impacts as a fraction of GDP
Conclusions-2
• Damages concentrated in large infrequent storms- 10% worst storms will cause 93% of total damages with CC
• Protect against high winds with coastal building codes
• Hard structures (sea walls) are ineffective protection against infrequent storm surge
• Restricted land use at low points along vulnerable coast