JUDY WOODRUFF: The floodwaters are still receiving from Hurricane Florence.
And the damage, which could total well over $20 billion, is still being assessed.
The flooding was far worse than the winds from this storm.
And it has prompted a larger conversation once again about what could happen to other
coastal cities.
That is the focus of Miles O'Brien's report tonight for our weekly segment on the Leading
Edge of science, technology and health.
MILES O'BRIEN: In Miami, it's not a matter of if, but rather when the big one will hit.
So, at Florida International University, they have built a wall of wind to buttress their
defenses.
IOANNIS ZISIS, Florida International University: So here's the intake.
MILES O'BRIEN: Wow.
IOANNIS ZISIS: We have...
MILES O'BRIEN: That's something.
IOANNIS ZISIS: ... 12 fans, six feet each diameter, 700 horsepower each.
And we can go up to Category 5 level winds.
MILES O'BRIEN: Ioannis Zisis is an associate professor in the Civil and Environmental Engineering
Department.
Here, they build scale models and subject them to hurricane-force winds.
It has shown them how buildings fail and how they can be built to endure a sustained barrage.
IOANNIS ZISIS: We need to understand how these structures are going to respond to an extreme
event.
Everything that goes into the building codes and the wind standards is a result of research.
MILES O'BRIEN: Hurricane Andrew was a pivotal moment.
The Category 5 storm made landfall south of Miami in Homestead on August 24, 1992.
The damage was widespread and made worse by inadequate building codes.
But that was then.
IOANNIS ZISIS: We're at a much better place compared to 1992 or even the '90s.
So, the building codes that are enforced today are much more strict.
MILES O'BRIEN: But today in South Florida, engineers and emergency planners are increasingly
worried about the threat from water.
Susy Torriente is the chief resilience officer for the city of Miami Beach.
SUSANNE TORRIENTE, City of Miami Beach: The lessons learned from after Andrew created
the South Florida building code, really for wind.
And that was adopted to the Florida building code.
How do we actually start looking at flooding and sea level rise and look at our building
code and start to add more measures in there for adaptation for that?
So I think that's something that we can learn from the past and bring it into the present.
MILES O'BRIEN: Miami Beach is a seven-square-mile barrier island that sits low between Biscayne
Bay and the Atlantic Ocean.
SUSANNE TORRIENTE: That makes us beautiful, but vulnerable.
And so we're vulnerable to flooding.
We're obviously vulnerable to the effects of sea level rise.
And, nowadays, the typical rainstorms that we would get in South Florida in the afternoons
seem to be getting more pronounced and stronger.
MILES O'BRIEN: And in the spring and fall, when the pull of the moon is strongest, creating
the highest tides of the year, the city must also contend with serious flooding beneath
blue skies and sunshine.
So they are in the midst of 80 storm-water pump stations to keep their feet dry.
The pumps, along with roads that are raised above grade, are doing the job for now, even
though those so called king tides grow steadily higher as sea level rises.
They are not designed to protect Miami Beach from a huge hurricane storm surge, though
they can help dry the city out after the worst is over.
But scientists are reminded there is no free lunch here.
Some say the pumps are dangerously concentrating runoff pollution.
Henry Briceno is a research professor at FIU.
HENRY BRICENO, Florida International University: We do monitoring in the Biscayne Bay, mostly
to see what's in the water.
That's what we do.
MILES O'BRIEN: He and his team use sophisticated instrumentation to gather data on the turbidity,
salinity and temperature, as well as the levels of oxygen and chlorophyll, important indicators
of the human impact on water quality.
In Miami Beach, we saw water pouring from this pipe, not from a pump.
It's just the outgoing tide mixed with contaminated groundwater.
And yet no instrumentation was required to determine the water was fowl.
All they needed was a human nose.
HENRY BRICENO: That smell is like a rotten egg.
It's very strong.
That's hydrogen sulfide.
And that comes from bacteria.
MILES O'BRIEN: Be glad you can't smell it.
And the outflows from the pumps are even worse.
For Briceno, the pollution problem is intertwined with the larger threat Miami faces as it grows
rapidly, despite the existential threat it faces from climate change.
HENRY BRICENO: I wonder they are aware that what they are doing is building in the future
Atlantis, and that the whole thing is going to get flooded?
MILES O'BRIEN: The idea that this city is inexorably on its way to becoming a real-life
version of the mythical underwater city is not a new one.
In 1958, "The Bell Science Hour" broadcast a film called "The Unchained Goddess" directed
by no less than Frank Capra.
ACTOR: Our atmosphere seems to be getting warmer.
ACTOR: This is bad.
ACTOR: Well, it's been calculated a few degrees rise in the Earth's temperature would melt
the polar icecaps.
MILES O'BRIEN: It explained the science of global warming, its consequences, including
sea level rise, and offered this depiction of the future:
NARRATOR: Tourists in glass bottom boats will be viewing the ground towers of Miami through
150 feet of tropical water.
MILES O'BRIEN: Today, that cartoon is showing signs of coming true.
Harold Wanless is a professor in the Department of Geography and Regional Studies at the University
of Miami.
He walks past a series of maps where current sea level rise projections are laid over the
Florida Peninsula.
HAROLD WANLESS, University of Miami: You can see, by six feet, Miami and Broward County
and Fort Lauderdale are now a little ridge with channels between them, and the Everglades
is an estuary.
MILES O'BRIEN: And South Florida must contend with a vulnerability unique to an area with
this population density.
HAROLD WANLESS: Miami limestone is one of the most porous limestones anywhere, and water
just pours through it very, very, very rapidly.
MILES O'BRIEN: At an excavation pit on the campus of the university, Wanless showed us
what the entire region is built on, a geologic sieve of limestone.
HAROLD WANLESS: As sea level continues to rise, in the same way that rainwater disappears,
the seawater will just come up.
MILES O'BRIEN: So, the hard seawalls and structures pioneered by the Dutch and adopted in New
Orleans to keep rising floodwaters and storm surges at bay would be utterly ineffective
here.
Henry Briceno hopes a sobering reality will sink in.
HENRY BRICENO: I'm sorry to tell this to people in Miami.
We're doomed.
And what we got to do is just protect as much as we can while we are living here, but get
prepared to move away.
MILES O'BRIEN: And yet, as Briceno plies the waters of Biscayne Bay, it is evident people
are moving in the opposite direction.
CLAY TOOTLE, Interscope Contractors: We're here on Key Biscayne.
This is one of the houses that we're building.
MILES O'BRIEN: Nice.
How many square feet here?
You know?
CLAY TOOTLE: It's about 8,000 square feet.
MILES O'BRIEN: Cozy.
That's developer Clay Tootle showing me an eight-figure climate change castle.
It sits nine feet above sea level, with concrete slab floors, walls and roof, where all the
systems, including a backup generator, will sit.
It will be fitted out with stout double-glazed windows.
He says features like this are now common for his wealthy clients.
You guys really have thought of everything.
CLAY TOOTLE: There's always something else to do.
But we try to get as much of it done as possible.
MILES O'BRIEN: How long is this house going to be a safe house to live, do you think?
CLAY TOOTLE: This will be a safe house for 30 years.
MILES O'BRIEN: After that, it is all but certain to be a fancy fortress with a moat, real estate
that is underwater, not financially, but literally.
For the "PBS NewsHour," I'm Miles O'Brien in Miami.