Hurricane Irma, one of the most powerful storms in recorded history, looks set to hit the continental United States in the coming days. If we are lucky the storm will veer back out to sea, but the National Hurricane Center’s forecast shows the hurricane bearing down on South Florida. Even if it only sideswipes the state, it will wreak havoc.
Florida is statistically due for a hit. According to the National Hurricane Center, 40 percent of hurricanes to strike the United States from 1851 to 2010 hit the Florida coast, a total of 114 hurricanes in 160 years. In other words, a hurricane hits Florida every year or so on average. Last year, Hurricane Hermine produced a nearly six-foot-high storm surge when it landed in northern Florida, but before that, the state went more than a decade without a single hurricane landfall. As the planet has warmed, development along Florida’s flood-prone coastlines has left more people more vulnerable to storms.
Four of the top eight cities in the United States most vulnerable to a major storm surge are in Florida, according to a recent report. This is not just because South Florida is extremely flat and low-lying, although this is certainly a major problem. More than half of the people in the United States who live four feet or less above sea level live in South Florida. In addition, cities like Tampa, Fort Myers and Sarasota lie alongside big areas of shallow water that produce strong storm surges when hurricane winds funnel water toward shore.
Aggravating matters, South Florida’s cities, in particular its largest, Miami, are built on porous limestone that’s effectively a rocky Swiss cheese. As the limestone soaks up rising seawater, Miami’s infamous “king tides” — fresh water forced up from drains and pipes by underlying salty water — become more frequent. Because of this limestone geology, Miami and other cities in South Florida cannot build substantial sea walls to hold back storm surges the way other cities, like New Orleans and Rotterdam, have. The water would simply flow underneath.