Talk to certain native Floridians about sea-level rise, and they'll scoff at the idea that the floods regularly swamping cars and drowning businesses in South Beach are anything new. "Why, I remember a flood in 1962 that you can't imagine!" they'll say.
Sorry, old-timey climate-change deniers. Miami Beach's flooding is definitely unprecedented, and it's happening at a shockingly more frequent rate.
That's the conclusion of a team of University of Miami scientists that used a wealth of data from everything from tidal records and rain gauges to insurance claims to look at how often Miami Beach's streets have ended up underwater. They found that since 2006, rain-based floods have increased by 33 percent and tidal flooding by an astounding 400 percent.
"That's a surprising number," says Dr. Shimon Wdowinski, the study's lead author. "Nobody can say whether it will continue increasing at this rate. But this is still clearly a significant increase in flooding events."
Wdowinski, an Israeli-born, Harvard-educated geophysics professor, says he was inspired to look into flooding frequency by a 2013 Rolling Stone magazine story headlined "Goodbye, Miami," about the grim prospects of sea-level rise in South Florida.
"This study all started from curiosity. I had heard a lot of talk in the media about flooding in Miami but hadn't seen any good data on how much it was increasing," Wdowinski says.
So the professor and three other researchers began diving into the data, which dated from 1998 through 2013 and included scientific records of tidal heights and rainfall amounts as well as insurance records, media reports, and photographs of the beach.
The most obvious change, Wdowinski says, was the rapid increase in major floods due only to ocean tides. Such "sunny-day floods," which often cluster around king tides — the year's highest annual tides in the fall — leaped from an average of one a year to around four serious floods annually.
"We analyzed the data, and what we saw was that starting about 2006, there was an increase in the number of tidal events," he says.
So what's behind the leap in floods? Wdowinski says global climate change is clearly the culprit, but the direct link to Miami Beach is a complicated mix of rising sea levels, changed ocean currents, and local water systems.
"It's tied to a much bigger picture, not just something happening locally here."
Wdowinski says he has watched with interest as Miami Beach has taken an aggressive approach to fighting the increased flooding, with a multimillion-dollar project to install pumps and raise street levels. He says the jury is still out on whether those measures will ultimately help, but he is glad to see the effort.
"I think people tend to become either in denial about this problem or they take the doom approach and believe nothing can be done," he says. "But I think we are actually in a period where we still have time to think both about intermediate changes and in the longer term about how to address this."