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Hurricanes and Climate

Hugh Willoughby, Florida Commission on Hurricane Loss Estimation Methodology

15AUG07

Present CO2 ~385 ppmv

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Focus on the Recent Past

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Geographical Distribution of Warming

How much of the apparent increase is due to incomplete observations in the past, and how much is due to climate change?

Accumulated Cyclone Energy by YearACE is the yearly sum of (Vmax)2 from HURDAT

Hurricane Heat Engines

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Great Ocean Conveyor Belt

Currents in the Atlantic account for¼ - 1/3 of the Northern-Hemispherepoleward heat transport

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Atlantic Multidecadal Mode

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1982 Hurricane Season

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Memorable Hurricanes of 1954 & 1955

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Gulf of Mexico Ocean Heat Content

Role of the Loop Current

Levees failed in CAT 1 conditions

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Actual and Simulated Catastrophic Hurricane Seasons

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Deaths 1900-2006

Halving Time = 27 yr

Note the 1970-2003 respite

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Inflation-Adjusted Damage 1900-2006

Doubling time = 15 yr

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Normalized Hurricane Damage

• Pielke & Landsea (1998, updated in press 2005)

• Corrects for:– Inflation– Population increase– Greater personal wealth

• What would historical hurricanes cost with 2005 population and development?

• Constant at $10B per year, based upon updated 1900-2006 data

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Normalized Damage 1900-2006

Doubling Time = 267 yr

Mean = $9.7B

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Summary• “Globe” is getting warmer

– Primarily in high latitudes– But does effect tropics (0.9 C since 1900)– Almost certainly Anthropogenic

• Atlantic Multidecadal Oscillation– 20-30 years in each phase– Thermohaline circulation– Warm phase, low shear, many hurricanes– Benign 1970-2003, despite active phase start in 1995

• Neither US landfalls nor US damage corrected for economic factors exhibit significant trends

• Random events produce clusters• Multiple working hypotheses• Landfall is when the vorticity hits the voters• What if the climate shifts to some completely bizarre new

mode?