The societal impact of hurricanes is one topic researched by scientists at the National Center for Atmospheric Research's (NCAR) Environmental and Societal Impacts Group (ESIG). While much of NCAR's research focuses on atmospheric phenomena itself, the social scientists who work in ESIG examine the impacts of society on the environment and the environment on society so that people can better cope with and understand what Mother Nature has to offer.

Mother Nature's wrath can be cruel. The balmy temperatures and warm seas of the world's tropical oceans are both the vacationer's dream and the birthplace of tropical cyclones and hurricanes. As the sun heats the oceans of the tropics, water evaporates and forms clouds which can grow into the thunderstorms that give rise to tropical storms or hurricanes. If atmospheric conditions are right, the clouds begin to rotate counterclockwise due to the earth spinning on its axis; this is called the Coriolis effect. The characteristic pinwheel shape of a hurricane or tropical storm when viewed on a satellite image is the result. The bands of spinning clouds hold flood-inducing rain while furious winds whip the ocean's surface into enormous waves. With storm surge and winds spanning up to thousands of square miles, hurricanes unleash the brunt of their power when they make landfall.

To determine a hurricane's damage potential, scientists use a scale developed in the 1970's by Robert Simpson, a meteorologist and director of the National Hurricane Center, and Herbert Saffir, a consulting engineer in Florida. The scale has five categories, with Category One being the least intense and Category Five the most intense. Storms that fall below the strength of a Category One storm but have winds greater than 39 m.p.h. are Tropical Storms. Public officials use the designation of a storm's intensity to make decisions about safety and risk (see Saffir-Simpson Scale of Hurricane Intensity).

Why worry about what can't be controlled? Although hurricanes develop every year between June and December, they don't always make landfall, or reach shore, in a crowded area, and not every hurricane is of extreme intensity. ESIG scientists like Roger Pielke, Jr. believe we have much to worry about, however. As a social scientist with a keen interest in how policy and science are connected, his goal is to help make science useful, relevant, and more focused. He examines the value in forecasting hurricanes, floods, blizzards, and other weather events in terms of understanding risks and the creation of policies that reduce society's vulnerability to damaging losses.

According to Pielke, "the physical dimensions of hurricanes are captured in questions like the following: How often do hurricanes strike a particular community? What is the expected intensity of these storms? Will the future climate resemble or differ from the past? The societal aspects of hurricane risk pose other questions. Do members of a community carry adequate insurance? Are evacuation plans in place? Are building codes implemented and enforced?"

The people who make policy decisions about such questions often do not understand the science involved in making sound decisions, and scientists don't always understand what those same policy makers need to hear. "Scientists and policy makers need each other. Scientific answers need to be translated to see their value in a bigger context," says Pielke.

One example of the confusion between science and policy that Pielke found is a 1995 congressional report on federal disaster assistance which incorrectly concluded that strong hurricanes have become more frequent in recent decades. The report stated that hurricanes "have become increasingly frequent and severe over the last four decades as climatic conditions have changed in the tropics." In fact, scientific data and the historical record show the opposite.

Although the cost of damage has increased significantly in recent decades, the frequency and severity of storms has actually decreased. The period from the 1940's through the 1960's saw much higher hurricane activity than the 1970's to the present. Some policy makers believed that increasing damage is caused by more storms, when in fact the damage represents increases in population along the coast from Texas to Maine, the increasing number of insured properties, and the increased value of those properties. Every time a hurricane makes landfall, there is more at stake.

A storm that made landfall many years ago would cause significantly greater economic and physical damage today simply because the dollar is worth less now and there are more people and property in vulnerable coastal locations. For example, in 1990 Dade and Broward counties in south Florida were home to more than the total number of people who lived in all 109 counties from Texas through Virginia along the Gulf and Atlantic coasts in 1930, says Pielke.

Sometimes people put too much faith in what science has accomplished, putting communities at even greater risk. Pielke found one 1996 news article with the lead "Great killer hurricanes, like those seen in decades past, appear to be gone forever from the shores of the United States because of early warning systems." Yet just one year earlier, in 1995, the director of the National Hurricane Center wrote that a "large loss of life is possible" unless significant policy change activities occur. Pielke has come to the troubling conclusion that the United States is more vulnerable today to hurricane impacts than it has been in recent decades because society accepts the risk of living in hurricane-prone areas without acknowledging the magnitude of that risk.

Take Hurricane Andrew for example. Not only was it a powerful Category Four hurricane with sustained winds over 130 miles per hour, it also made landfall in a populated area of Florida. While loss of life was fewer than 50 people, the cost of the damage was over $30 billion.

The cost, however, could have been significantly less had society done a better job of preparing for such a hurricane. Even though Dade County, Florida, has some of the toughest building codes in the United States, the damage was devastating. The reason? The codes were not strongly enforced. Some insurance industry estimates suggest that failure to enforce the codes accounted for between $4 and $6.5 billion of the insured losses related to Andrew.

Andrew is considered one of the worst natural disasters in history and the costliest ever in the United States, but the cost would have been far higher had the hurricane tracked slightly north and hit Miami. After Hurricane Andrew, Dr. Robert Sheets, the director of the National Hurricane Center, testified before Congress that "We were lucky." The luck is simply that had Hurricane Andrew tracked a mere 20 miles north of where it made landfall, two studies estimate that losses could have exceeded $60 billion.

Pielke wants people to make a stronger practical link between the atmospheric science of hurricanes and their impact on society. He wants to translate the science so that it can be used to make effective decisions to save lives and property. He is a good person to make such translations because he maintains a close working relationship with an atmospheric scientist who researches hurricanes--his father. Pielke and his father, Roger Pielke, Sr., recently co-authored a book titled "Hurricanes: Their Nature and Impacts on Society," (John Wiley and Sons Press, 1997) which examines both the physical phenomena of hurricanes and how the storms affect people.

Some scientists are predicting that based on changing atmospheric conditions, the U.S. may be entering another active hurricane period like that of the decades prior to the 1970's. If those scientists are correct in their predictions, the United States may have to pay for devastating damage in coming years. Factors which affect hurricane intensity and frequency include elements such as rainfall in West Africa, stratospheric winds, sea surface temperatures, and the presence or absence of El Nino, a huge pool of warm water that develops in the eastern Pacific and changes weather patterns worldwide. El Nino tends to decrease Atlantic hurricane activity. In August 1997, with a major El Nino in progress, there wasn't a single Atlantic tropical storm or hurricane for the month--a first since August 1961.

To anticipate the future, one must often examine the past. Pielke went back through hurricane data from 1900 to present and estimated losses from hurricanes as if those hurricanes made landfall in 1995. In other words, he used 1995 dollar values, population figures, and property values or wealth to determine what such hurricanes would cost today. He found that even though intense hurricanes of Categories three, four, and five make up only 21 percent of the storms making landfall in the United States, they account for 83 percent of the damage costs. The 52 intense hurricanes that struck the United States from 1925 to 1995 resulted in an average of $5.5 billion per storm. Hurricane Andrew actually dropped into the number two position because the 1926 SE Florida/Alabama hurricane, a Category Four like Andrew, would have cost more than double that of Andrew if it made landfall today.

So what can society do? Hurricane-dissipating technology is the stuff of science fiction, so scientists strive to improve forecasting and early warning systems. With that knowledge public officials must make decisions about building codes, evacuation plans, insurance requirements, and potential taxpayer costs with an appropriate understanding of the risks of habitation in hurricane-prone areas. Ultimately, everyone shares the cost if those decisions are not made wisely. Roger Pielke, Jr. works to impart that wisdom.