Chris Landsea, Ph.D.
NOAA/Hurricane Research Division, Miami, FL
Prof. Bill Gray
Colorado State University, Ft. Collins, CO
Miami Herald, 23 July 2002
Hurricanes have always been synonymous with Florida, back to the time of Juan Ponce de Leon's explorations here. While historical records are incomplete before 1900, Florida is clearly the epicenter for hurricane strikes in the United States. Florida experienced 62 hurricanes in the 20th Century, with 23 of these reaching "major" hurricane status - Saffir-Simpson Category 3, 4 or 5 with sustained winds of at least 111 mph at the coast. These numbers dwarf the 37 hurricanes, of which 16 reached major hurricane status, that the second most active state - Texas - has experienced. Major hurricanes - like the "Lake Okeechobee Hurricane" of 1928, the "Labor Day Hurricane" of 1935, Hurricane Donna of 1960 and Hurricane Andrew of 1992 - are the ones of most concern since these cause over 80% of the storm-caused destruction even though they only account for about one-fifth of all landfalling tropical storms and hurricanes. With the ten year anniversary of Hurricane Andrew now upon us, one could (and should) ask what might be in store in coming years for the United States' most vulnerable hurricane state.
Last August, we were co-authors on a research paper led by our colleague Mr. Stan Goldenberg in the journal _Science_ that came to two big conclusions about major hurricanes. The first is that major hurricanes tend to occur in cycles of active and quiet periods that last between about 25 to 40 years each. This switching between active and quiet eras is due to a natural fluctuation of the water temperatures and atmospheric conditions governed by the Atlantic Ocean itself. The second finding was that as of about 1995, the major hurricanes of the Atlantic basin had made a return after a 25 year lull and were likely to continue to be more numerous for about two to three more decades. Such a result has large repercussions to the general public, business owners, emergency managers and government officials not only in the United States, but also to our neighbors in the Caribbean and Central America. The natural question is how does this change to active conditions manifest itself in Florida?
Unfortunately, the answer is not good news. Florida shows a dramatic change in major hurricane strikes due to this multi-decade flip-flop in activity ( Figure 1). In the 53 years of busy hurricane conditions in the 20th Century, Florida experienced 16 major hurricane strikes compared with just 7 major hurricanes in the 47 years of light hurricane activity. This works out to about three major hurricanes making landfall in Florida per decade in the active era versus one and a half major hurricane per decade in the quiet era - a doubling in the major hurricane landfalls expected.While these changes are for all of Florida's coastline, these active versus quiet differences are most pronounced in southern Florida, from Tampa-St. Petersburg to the Keys to Miami-Ft. Lauderdale to Cape Canaveral.
If all else remains the same, a temporary increase in major hurricanes making landfall in Florida might not be too disruptive to the environment since presumably the ecology of the region had adapted to this natural swing that has been going on at least hundreds, if not thousands of years. However, in ever-changing Florida, nothing remains the same when it comes to people. The population in Florida has dramatically increased: coastal county residents numbered only about 200,000 in 1900; about a million in 1930; and over 13 million today. In addition to these huge increases in numbers of people, we are also quite a bit wealthier as a whole today. U.S. residents are twice as wealthy per capita now (twice as many possessions essentially) as we were 40 years ago. These factors of population and wealth account for why hurricanes today are much more destructive in terms of human impact than they used to be.
The combined effect in the next few decades of more landfalling major hurricanes in Florida with very large and increasing coastal populations with much more property at risk leads to a recipe for disaster. Projections of major hurricane strikes and population/wealth changes over the next twenty to thirty years lead to some amazing conclusions. We anticipate that the rate of economic loss in the state of Florida due to hurricane landfalls will be about SIX TO EIGHT TIMES the rate that occurred during the 1970s, 1980s and 1990s. Anyone living in or doing business in the state of Florida needs to heed these warnings of probable impacts in the future and to best plan for them.
In addition to impacts financially, concerns loom about the possibility of a large number of fatalities from a major hurricane making landfall. If an incomplete evacuation occurs due to either an unanticipated rapid intensification of a hurricane at landfall or due to apathetic residents choosing foolishly not to evacuate until too late on congested roadways, then hundreds or even thousands of Florida residents could drown in a hurricane's storm surge. Clearly, a doubling in the number of landfalling major hurricanes in Florida means that residents must listen to the advisories of the National Hurricane Center and take action when appropriate, as suggested by local emergency management officials.
The bottom line is that Florida is the proverbial "sitting duck" in the Atlantic major hurricane "firing range". This is even more the case when the Atlantic Ocean has altered to a more active era during the next twenty to thirty years, with a doubling of landfalling major hurricanes in Florida causing much more damage we have seen in recent years. While Hurricane Andrew was a devastating hurricane for Florida ten years ago, it is far from the worse case scenario in causing major destruction and fatalities. If the 1926 Great Miami Hurricane - nearly as intense as Andrew, but double or triple its size - were to hit today's south Florida, there would likely be on the order of $70-80 BILLION in damages in Miami-Dade and Broward counties. By far the biggest decade during the last active era was the 1940s, when five major hurricanes made landfall in Florida. This contrasts dramatically with the very low activity of the 1970s, 1980s and 1990s. The question is - are we ready for a repeat of these past busy periods in Florida today? (Figure 1). It is the purpose of this note to alert Floridians of these concerns for the future, so that individuals, families, businesses, communities and the state can best get ready for increased numbers of major hurricane strikes. As the sage old saying goes, we should hope for the best, but prepare for the worst.
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