Saturday, September 13, 2008

The Effectiveness of Preparedness

On Thursday, when hurricane Ike was thought likely to make landfall in Texas as a class three or stronger, its predicted impact included a Galveston Island storm surge of twenty feet or more. The National Weather Service issued a strongly-worded warning for coastal areas of Texas, and urged evacuation.

A storm similar to Ike's predicted power had hit Galveston square-on before, in 1900. During that storm, locals did not evacuate but had actually gathered on the beach to observe the waves. The only non-marine egress from the island at the time was "the longest wagon bridge in the United States" and there was no manmade storm surge barrier on the island. Six thousand are known to have died in Galveston's storm of 1900, and the complete count of the dead is thought likely between eight and twelve thousand. Thousands more were injured, and approximately ten thousand left homeless.

According to the United States Census of 1900, the population of the United States stood just under 76 million inhabitants. The loss of eight thousand (the number offered by the National Oceanic and Atmospheric Administration) amounts to about one hundredth of one percent of the national population. During the census year ended in May, 1900, the annual death count was about a million and a half, suggesting that the loss of 8,000 souls contributed about a half a percent the then-current all-causes annual death toll. On the other hand, understanding the scale of the disaster may be aided by considering that the Texas death toll in the 1900 census was less than one hundred thousand, and that the population of Galveston was less than twenty thousand. (Today, the population is sixty thousand.) If you are nearby, it looks terrible indeed.

The construction of fifteen-foot storm barriers against the encroaching ocean contributed to Galveston's improved outcome when it later faced a similar storm surge:
In 1915, a storm of similar strength and track to the 1900 hurricane struck Galveston. The 1915 storm brought a 12 foot (4 m) storm surge which tested the new seawall. Although 275 people lost their lives in the 1915 storm, this was a great reduction from the thousands that died in 1900.
from Economist's View
Today, storm surveillance and still-developing emergency-response strategies have enabled the hurricane death count to be controlled to a mere four. Granted, uncooperative non-evacuees peppered emergency numbers all night with futile pleas for evacuation, and more might have been killed on Galveston had the storm surge hit those choosing to remain with the predicted twenty-foot-plus surge rather than the surge that materialized. However, people who choose to ignore a plea for evacuation like this take their lives in their own hands. It's not the same as breaking into a junkyard to taunt hunger-maddened dogs while wearing a cat costume to win a home video competition, but it's not far behind. The four and a half million without electricity will eventually get power restored, including the sixty thousand on Galveston.

Unlike freak acts of nature that might or might not strike, known sources of human-caused risk create an evergreen source of mortality, morbidity, and property damage. For example, accidental drownings in recreational environments aren't a result of the weather or unavoidable astronomic phenomenon such as meteor strikes, and they routinely kill thousands of Americans annually. The Centers for Disease Control and Prevention -- the "Prevention" was added to the CDC's name recently enough that the agency is still called the CDC -- has a special page devoted to drowning risk. Accidental drowning in recreational environments is such a significant cause of death that -- despite widespread laws requiring home pools to be fenced, swimming training programs, and laws ensuring boater access to life vests -- recreational drownings eclipsed terrorist attacks as a leading cause of mortality even in the year of the high-water mark of terrorist attack fatalities in the United States. One wonders how much worse drownings could be, but for the effort to control its toll.

One way to illuminate the effectiveness of preparedness is to look at the progress the United States has demonstrated against another manmade mortality risk: driving-related fatality. During the 1980s, the approximately-fifty-thousand annual death toll from driving-related incidents in the United States challenged the country's cumulative death toll of the entire Vietnam war. Despite increasing numbers of drivers and increasing numbers of miles driven, efforts to control risk -- including interventions like mandatory seat belt laws, education on driving risk, and the implementation of widespread designated driver promotion programs -- have decreased the absolute number of annual deaths. The rate has plummeted even more. (It turns out that alcohol is a nontrivial contributor to drowning fatality risk, too.)

Risk-control interventions significantly impact materializing losses. The question is whether the results are worth their human and financial cost. In the case of avoided drownings and avoided road deaths, it's easy and politically non-controversial to conclude that prevention is money well-spent.

The question is how to develop a policy analysis framework with the power to address situations in which political views heavily color viewpoints.

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