Tropical Cyclone Modification: Decision-Analysis and Public Perceptions

Photo courtesy of NASA: STS047-151-618 Hurricane Bonnie (1992)

Tropical Cyclone Modification: Decision-Analysis and Public Perceptions

Kelly KlimaWändi Bruine de Bruin, Kerry Emanuel, Iris Grossmann,

Granger Morgan

SEA talkApril 22, 2011

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Today we will discuss two components of my research.

• Does Tropical Cyclone Modification Make Sense? A Decision-Analytic Perspective – Background– Results

• Public Perceptions of Hurricanes and Hurricane Modification– Interview– Survey– Results 2

Two general approaches exist for controlling hurricane damage

Hardening structuresCurrently practiced nationwide

Called “mitigation” by FEMA and others

Includes shutters, dams, better roof connections, etc

Works better for moderate storms

3How do hardening and modification compare?

Hurricane modificationTheorized since 1930s

DHS has recently reopened research into the topic

Works better for large storms

A commonly suggested hardening technique is home shutters

4Figure courtesy of Hurricane Proof

Annualized cost to shutter all houses (30yrs, 5% discount rate)

Florida = $1.4-1.8BGeorgia = $0.7-0.9B

The modification technique closest to implementation is wind-wave pumps

5Figure courtesy of Philip Kithil, Atmocean

300m pipe is optimal

Deployment Cost

Seasonal = $0.9-1.5B

Per TC = $0.4-0.7B

We find modification may be more competitive than hardening

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Control

Benefit-cost analysis alone does not capture the complexity of this decision

• Hardening and modification may be done in parallel

• Other issues include uncertainty, liability/ethics, risk tolerance, political/budgetary/time restraints

• Remaining doctoral work will be completed by fall – Storm surge damages, Ning Lin, Kerry Emanuel (MIT)– Public perceptions of hurricanes, Wändi Bruine de Bruin

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I examined public perceptions of hurricane modification in Florida

• How does the public evaluate hurricane modification compared to its alternatives?

• How does anger at scientists vary across hurricane modification scenarios?

• How is anger at scientists related to recognizing the uncertainty inherent in hurricane forecasts? 8

Ten Florida residents were asked general nondirective questions over a telephone

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• Topics– General Knowledge– Damages– Modification– Forecasts– Definitions

• Demographics – 5 women– 7 living in a house– 10 with high school education– 4 with college degree

We prompted for details while maintaining a friendly and nonjudgmental

tone.

Hurricane modification is largely unknown, and distrusted

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• Only one person suggested hurricane modification as a way to decrease damages from hurricanes

• “Have you ever heard about the possibility of changing hurricanes to reduce their damage?”

“You can’t change nature”

“It will never be possible”

Hurricanes are “too big and powerful to

be changed”

The government might be “using

some kind of secret weapon or something”

Commission may lead to public resistance independent of the outcome

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• “How much of the problem is because scientists don't understand hurricanes, and how much is because sometimes nature can't be perfectly predicted?”

• Strong expressions of fear and anger were evoked by all hurricane modification scenarios including where unintended consequences were due to the natural variability

A larger sample is needed to systematically examine people’s response.

100% of respondents

A total of 157 individuals in the Miami, Florida area completed an online survey

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• Topics– Damages– Uncertainty– Expected Landfall

Locations– Emotional Response to

Hurricane Modification– Hurricane Modification

Scenarios– General Knowledge– Demographics

• Demographics – Age: 40 (SD=15)– Salary: $74.3K (SD=$52.9K)– 66.7% women– 78.4% live in an urban area– 50.6% in an easily flooded area– 57.3% live in a single story home– 3.1 people per household, with

0.98 children and 0.18 elderly, infirm, or handicapped

Hurricane modification is unfamiliar and perceived as ineffective

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• In free form response, no one mentioned hurricane modification as a way to reduce damages.

• “How effective in reducing damages [are these] in Miami, Florida?”– Stronger conviction than the midpoint, p<.001

Having buildings up to code, Cutting old tree branches, Bringing in loose lawn items, Putting the car in the garage, Using hurricane shutters, Being prepared (with enough food, water, and batteries), Using tie-downs to strengthen wall to roof connections in buildings, Raising coastal buildings above ground level by struts or some other method, Having better dikes (walls that keep out the ocean), Evacuating everyone but emergency personnel, Using metal roofs, Hunkering down (sheltering in place) in a secure part of the house, Building new buildings farther from the coast

– Lesser conviction than the midpoint, p<.001A government attempt to change a hurricane to reduce damage

In the future, scientists will likely try to change a TC to help people, but it’s a bad idea and won’t work

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Interviewees’ statements (11 in total) Mean (SD) Agreement

Scientists will most likely try to change a hurricane to help people 4.35 *** (1.28)If the government tries to change a hurricane, they are trying to help the general public

3.89 *** (1.50)

It is a bad idea to change a hurricane because it might make things worse

3.59 *** (1.80)

Hurricanes are too big and powerful to ever be changed by humans 3.49 ** (1.83)

One-sample t-tests examined whether statements differed from the midpoint (=3), indicating beliefs held with stronger conviction (***

p<.001; ** p<.01)

0=completely agree, 6= completely disagree

The government will use the ability to change storms as a weapon 2.34 *** (1.86)Today, it is possible to change a hurricane to reduce its damage 1.32 *** (1.29)

Respondents expected hurricane modification would change a storm

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A Cat 1 or Cat 5 is expected to make landfall at position 4

After hurricane modification,• Landfall location is expected

to move, and uncertainty decreases

• Intensity is expected to decrease.

Respondents were angrier when there were higher damages and when the hurricane hit them

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Hurricane scenarioPath

compared to prediction

Damage compared to

prediction

Mean (SD) anger at scientists, 0 (=Not at

all) to 6 (=Extremely)

Same More 2.89 (2.10)Same Same 1.75 (1.86)Same Less 1.03 (1.52)

Different More 3.48 (2.08)Different Same 3.06 (2.10)Different Less 1.88 (1.80)Those displaying more uncertainty were angrier.

Participants recognizing forecast uncertainty were angrier at scientists

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Follow-up Question: Would teaching people about hurricanes and modification techniques will help or hurt

their willingness to accept hurricane modification?

Resultant Damages

Recognizing Forecast

Uncertainty

Anger at scientists

Our findings do not bode well for supporters of hurricane modification

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HOWEVER….• If the efficacy of techniques can be increased,

people may be willing to support hurricane modification

• Open and honest communication between scientists and public would be needed.

A carefully explained technique that is effective against wind and/or flooding damages and does not change

track may be acceptable to Florida residents.

Kelly KlimaPh.D. candidate

Engineering and Public Policy, Carnegie Mellon [email protected]

K. Klima, M. G. Morgan, I. Grossmann, K. Emanuel. "Does it Make Sense to Modify Tropical Cyclones? A Decision Analytic Assessment". Submitted to ES&T.

Funding provided by: