For much of the Northeast, Hurricane Sandy was a harsh wake-up call to the extreme weather destruction that can be amplified by climate change. But Sandy's warning is also resonating in states further south along the Atlantic, which escaped the brunt of the storm but face equal, if not greater, risks from the combined effects of sea level rise and intense storms.
Florida is particularly vulnerable. A 2007 climate change study that mapped how a 9.8-foot sea level rise would affect New York City—maps eerily similar to the flooding from Sandy's 9-foot storm surge—also offered a look at how Florida would be affected. If anything, the images are even more chilling.
The scenarios for Florida are based on a sea level rise of roughly 3 to 7 feet. The coastal fringe of downtown Miami, where many of the city's luxury hotels are located, is covered in blue—the map's symbol for inundated land. Nearly all of Key West would be underwater, except for a few pockets of high ground including the area near Key West Cemetery. Fort Lauderdale would be flooded along most of its coast, as would downtown Tampa.
The study was published by Architecture 2030, a nonprofit that seeks to reduce the carbon footprint of the building sector. Founder Edward Mazria said the key difference between storm surge and sea level rise is that the former is temporary while the latter is permanent.
After a severe storm, cities like New York can rebuild, Mazria said, because the surge of water will drain off and leave the land dry again. But sea level rise is permanent and will force people to "either abandon the area or, if it's extremely valuable territory, then you [can] expend up to tens of billions of dollars" to protect it with sea walls and other measures.
Some communities could also adapt by constructing buildings on stilts, he said, or by lifting smaller structures off their foundations and moving them to higher ground.
According to recent projections by the U.S. Geological Survey, the world's ocean levels will rise about 2 to 6 feet by 2100. That would be devastating for Florida, where the average elevation of the entire state is only a few feet above sea level. In July, the Organization for Economic Cooperation and Development (OECD) ranked Miami as the city in the world with the most to lose from sea level rise.
Although climate change has become divisive in the national political debate, it's much less controversial in southern Florida, where it already affects everyday life, said climate expert Leonard Berry.
Berry is a professor at Florida Atlantic University in Jupiter, about 60 miles north of Fort Lauderdale. On October 11, two weeks before Hurricane Sandy made landfall, he was among the 121 Florida scientists and public officials who signed a letter urging President Obama and Mitt Romney to discuss climate change at the Boca Raton debate.
"Florida is already feeling the effects of sea level rise and, increasingly, it jeopardizes the health, safety, and economic well-being of our communities," they wrote.
According to a recent analysis of the U.S. coastal population by Climate Central, a nonprofit dedicated to climate change research and reporting, nearly 5 million people live less than four feet above sea level. About half of them are in Florida.
Berry said southeast Florida is particularly vulnerable due to its low elevation, susceptibility to powerful storms and a porous geology that allows saltwater to seep in underground.
"The water not only comes over the land, it comes through the land," he said. The saturated ground also makes it more difficult for water to drain off the land after a storm or high tide event.
The effects in Florida are noticeable even under normal weather conditions. Water from seasonal high tides now creeps up driveways and seeps under sea walls. Along the coast, Berry has seen cars submerged to their hubcaps as the tide backflows through the drainage system.
Some Florida cities are taking major steps to adapt to the changing climate. Miami Beach is considering spending $206 million to update its drainage system with more pumps, higher sea walls and wells to store stormwater runoff. Hallandale Beach, in Broward County, recently paid $10 million to drill new water wells after saltwater seeped into six wells along the coast.
Saltwater intrusion is a regional problem in southeastern Florida, where residents depend on the Biscayne aquifer for drinking water. As sea level rises, their wells are increasingly contaminated with saline water.
"It's a serious problem," Berry said. "In the long run—20, 30 years from now—it may mean using different water sources."