| Agnes. Andrew. Bertha. Camille.
Gilbert. Hugo. Opal. Roxanne. This list of names holds little significance
to much of the world's population, but to the people who endured the
fury of these hurricanes, the names recall a host of devastating memories.
The impacts of these violent tropical storms spawned over the warm
waters of the world's oceans reach well beyond the coastal areas they
pummel with wind and water. The storms, which are the costliest of
all natural disasters in the United States, exact a heavy price in
lives and property, and affect the way people live.
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
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
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
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.
Scale of Hurricane Intensity
Category One Hurricane:
Winds 74 - 95 m.p.h. Storm surge generally 4 - 5 feet above
normal. No real damage to building structures. Damage primarily
to unanchored mobile homes, shrubbery, and trees. Some coastal
road flooding and minor pier damage.
Category Two Hurricane:
Winds 96 - 110 m.p.h. Storm surge generally 6-8 feet above
normal. Some roofing material, door, and window damage to
buildings. Significant damage to shrubs and trees with some
trees blown down. Considerable damage to mobile homes, poorly
constructed signs, and piers. Small craft in unprotected anchorages
break moorings. Hurricane Bertha of 1996 was a Category Two
hurricane when it hit North Carolina.
Category Three Hurricane:
Winds 111 - 130 m.p.h. Storm surge generally 9 - 12 feet
above normal. Some structural damage to small residences and
utility buildings. Foliage blown off trees and shrubs and
large trees blown down. Mobile homes destroyed. Low-lying
escape routes are cut by rising water 3 - 5 hours before arrival
of hurricane center. Flooding near the coast destroys smaller
structures and larger structures damaged by floating debris.
Terrain continuously lower than five feet above mean sea level
may be flooded inland eight miles or more. Hurricanes Fran
and Roxanne were Category Three storms.
Category Four Hurricane:
Winds 131 - 155 m.p.h. Storm surge generally 13 - 18 feet
above normal. Some complete roof structure failures on small
residences. Shrubs, trees, and all signs blown down. Complete
destruction of mobile homes. Extensive damage to doors and
windows. Low-lying escape routes may be cut by rising water
3 - 5 hours before arrival of the hurricane center. Major
damage to lower floors of buildings near the shore. Terrain
lower than ten feet above sea level may be flooded, requiring
massive evacuation. Hurricanes Andrew and Hugo were Category
Category Five Hurricane:
Winds greater than 155 m.p.h. Storm surge more than 18 feet
above normal. Complete roof failure on many residences and
buildings. Some complete building failures with small utility
buildings blown away or over. All shrubs, trees, and signs
blown down. Complete destruction of mobile homes. Severe and
extensive window and door damage. Low-lying escape routes
may be cut by rising water 3 - 5 hours before arrival of the
hurricane center. Major damage to lower floors of all structures
located less than 15 feet above sea level and within 500 yards
of shoreline. Massive evacuations of areas on low ground within
5 - 10 miles required. Hurricane Gilbert of 1988 and Hurricane
Camille of 1969 were Category Five storms.
(This information was adapted from the National
Hurricane Center Website@ http://www.nhc.noaa.gov)