City's flooded future

Take a ride around the Charleston Peninsula when the tide is high, preferably at the highest tides during the full moon phase. Stay as close to the water as the roadways allow and you will be impressed that downtown Charleston is a city at a very low elevation.

Now in your imagination, raise the level of the ocean by 1-foot and you can sea that some streets and sidewalks and even some buildings will be flooded.

Continue using your imagination and conjure up a small storm with a storm surge of 2 feet.

Between the 1-foot global sea-level rise, the addition of a high tide, the addition of a 2-foot storm surge plus the storm waves on top of it all and the entire Charleston Peninsula will be flooded. In fact with a 1-foot rise in sea level, even a small to moderate storm occurring at low tide will likely flood large parts of the city.

Charleston is flooded now during big storms, as happened in Hugo, but with a sea-level rise, it will flood repeatedly during small storms. The uncertain behavior of the world's ice sheets in Antarctica and Greenland hold the key to the future of the sea level. Indications are that the scenario of a 1-foot rise in sea levels could be a reality in a few decades.

The Dutch, who pay more attention to sea level matters than any other society, assume for planning purposes that the sea level will rise 2-1/2 feet by the year 2050. Panels of scientists from Miami/Dade County and Rhode Island have recommended that coastal management decisions be based on the assumption of a minimal 3- to 5-foot rise by the end of this century.

Drawing lines on maps showing where the shoreline will be as the result of a sea-level rise can be misleading. It's not just the flooding that will drive people from Charleston (if no safety measures are taken). Before the floods actually arrive, storm surges, storm waves and the loss of infrastructure such as the loss of ports, roads, railroads, storm-water drainage and sewage-disposal facilities will make the peninsula unlivable. Putting it another way, the Port of Charleston facilities will be rendered useless long before they are actually flooded by sea level increases.

Charleston is one of a number of threatened cities. These include Boston, New York/Newark, Philadelphia, Washington, D.C., and Miami. Miami is by some measures the world's most endangered city as measured by the value of property at low elevation threatened by a sea-level rise of around 2 feet. The Charleston peninsula is as poorly situated for sea level rise as Miami, but of course, the area and population is much smaller.

Until now, the nation's attention has been riveted on beach- front property where spectacular photos of houses falling in during storms abound. But the time has come for the cities. I believe that in coming decades the nation's attention will be riveted on urban sea-level flooding.

Barrier island recreational property will soon become low priority for the nation's resources. If Manhattan and Miami are in trouble, Folly Beach and Isle of Palms will be marginalized as far as federal funding is concerned.

The time has come to start planning for the future of the Charleston Peninsula (and the rest of Charleston) in anticipation of a major rise in sea level.

Should levees be built? Should buildings be moved back or abandoned? If levees are built, some historic buildings and many sea views may be sacrificed. And what about the miles of estuarine and river shorelines that constitute the rest of Charleston?

Planning will require years of effort. It's time to start now.

Orrin Pilkey is the James B. Duke professor of geology emeritus at the Nicholas School of the Environment at Duke University.