The Palm Beach Post: Palm Beach County particularly vulnerable to rising seas

Damaged sea walls and erosion caused by Hurricane Sandy along South Ocean Blvd. in Manalapan on Tuesday, Oct. 30, 2012. (Gary Coronado/The Palm Beach Post

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By Eliot Kleinberg

Palm Beach Post Staff Writer

NEW ORLEANS — Just a short drive from the lights of Bourbon Street, a chunk of the southern Louisiana coast equal to the 100-yard football field at the nearby Superdome is washing into the Gulf of Mexico.

It happens every 15 minutes.

What’s happening in Louisiana could easily be on the horizon for Palm Beach County and the Treasure Coast.

The debate continues to rage about whether climate change is caused by civilization or part of a natural cycle. But research is suggesting sea levels definitely are rising, although there’s still uncertainty about how much and how rapidly.

And people keep moving to the coast. That’s a grim enough combination already, even more so when you throw in hurricanes.

“We love our coasts to death,” Margaret Davidson, said last week at the opening session of the National Hurricane Conference. Davidson is acting director of the National Oceanic and Atmospheric Administration’s Office of Ocean and Coastal Resource Management, based in Charleston, S.C.

Even as far back as 1992, a study suggested sea level could increase between six inches and three feet by the year 2100, more than double the rate for the previous century.

“Entire communities are being developed without adequate consideration of the potential costs of erosion, flooding, and storm damage related to sea level rise,” the U.S. Geological Survey said in a report. That was in June 2000.

Palm Beach County and the Treasure Coast are highly vulnerable to sea level rise. Factors include the range of high and low tides, wave heights, the slope of the coast, rates of shoreline erosion, and the erosion potential for a specific section of shoreline.

There’s no immediate concern that oceanfront mansions will fall into the ocean or that the beach soon will begin at Military Trail. But Davidson said later in the week that sea level rise affects more than beachfront property. The water table also rises, which means higher levels in canals and ponds, and higher risk of flooding if a storm threatens.

A study done in October by the “Southeast Florida Regional Compact Climate Change” said a one-foot rise in sea level would threaten property across Palm Beach County with a total taxable value of $396 million to $557 million. In a catastrophic three-foot rise, the value of flooded properties would be $3.6 billion to $4.5 billion.

At the same time that nature is working on the shoreline, the number of people living there, is going up, up, and up, according to a report released last week.

The joint NOAA-U.S. Census report said the increasing population growth in a strip of 452 U.S. counties directly on the coast means that many more people are threatened by hurricanes, which of course hit the coast before anyplace else.

According to the report, which used the 2010 census, those shoreline counties account for less than 10 percent of the total U.S. land area, excluding Alaska, but host 123 million people, nearly four in 10 Americans.

Their populations are more than six times greater than those just in the adjoining inland counties.

But in just four decades, from 1970 to 2010, the population in those counties jumped by 39 percent. In Florida, it was 165 percent.

In the past four decades, while the country added 36 people per square mile, coastal shoreline counties added 125 people.

The numbers now come out to 446 people per square mile, compared with 105 per square mile nationwide, excluding Alaska. Florida’s coastal shoreline counties are on par with 454 per square mile.

The nation’s coastal population is expected to increase 8 percent from 2010 to 2020; that’s 10 million more people.

From 2000 to 2010, 1,355 building permits were issued in coastal shoreline counties every day. And total housing units increased 8 percent. In Florida’s coastal counties, population is expected to jump by even more: another 16 percent.

The percentage of the most vulnerable is going up as well; from 1970 to 2010, the number of people 65 and older in the nation’s coastal counties increased by 89 percent.

Even when Max Mayfield ran the National Hurricane Center, from 2000 to 2007, he was on the soapbox about the completely preventable — and yet all but impossible to stop or slow — migration to the coast, and how that marked perhaps the greatest threat.

Now, especially in southeast Florida, he said at last week’s hurricane conference, “even if you stopped right now, we’ve got so many people that we are at great risk.”

In last week’s NOAA-Census report, the prognosis, according to Holly Bamford, assistant NOAA administrator for the National Ocean Service, means that local governments, planners, and emergency managers “will see a dual challenge: protecting a growing population from coastal hazards, as well as protecting coastal ecosystems from a growing population.”

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