Miami is racing against time to keep up with sea-level rise

Apr 12, 2018

  • Miami and Miami Beach already struggle with serious flooding related to sea-level rise — even when there is no rain.
  • The ground under the cities of South Florida is largely porous limestone, which means water will eventually rise up through it.
  • The cities are taking flood-control measures like installing pumps, raising roads, and restoring wetlands.
  • Coastal cities around the world face similar problems.

When the flooding is really bad, water doesn’t just fill the streets outside Manolo Pedraza’s house. It bubbles up through a shower drain.

Pedraza lives in Shorecrest, a northern Miami neighborhood that faces flooding so regularly it happens even when it hasn’t rained. All it takes to fill the streets to knee-high depth on those days is a full moon. The flood comes up through storm drains, making it impossible to navigate without encountering the water, which is mixed with sewage and whatever else it picked up along the way.

During a visit to Pedraza’s neighborhood, I walk only where the water, likely filled with fecal bacteria, won’t rise above my waterproof boots. I’m lucky that day. Pools cover parts of the streets, but at least I can walk the area without soaking my feet.

“This is nothing,” Pedraza said in Spanish. “Sometimes it comes all the way up to the house.”

The “sunny day flooding,” as it’s known, is consistent enough that you can look at a calendar and a tide chart to plan a trip around it. High tides, caused by interactions between the sun, moon, Earth, and oceans, are behind the flooding. I visited during what are often the highest tides of the year, known as king tides.

Miami “is kind of the poster child for a major city in big trouble,” said Jeff Goodell, author of " The Water Will Come: Rising Seas, Sinking Cities, and the Remaking of the Civilized World."

Beyond the damage to homes, roads, or other infrastructure, the flooding also threatens drinking water and plant life. Ultimately, of course, it means large parts of the city could become permanently uninhabitable.

That means the rest of the US should be paying close attention to how Miami handles its struggle against sea-level rise in the coming years. It could provide a window into the future for other large coastal urban areas.

The Netherlands has been holding back the oceans for decades and is exporting its knowledge to cities such as New Orleans. But the Dutch have been building on land reclaimed from the sea. In Miami it's a different situation.

When low-lying neighborhoods in Miami and nearby Miami Beach were built up decades ago, they weren’t developed with the assumption that seas would rise over time. In some places, buildings and roads are being raised or moved; in others, natural features like mangroves, reefs, and wetlands are being restored.

Those are the kinds of changes that might be enough to keep much of Miami above water for at least a few decades. Planning longer term is trickier.

Water is coming for Miami from all sides

You can break the major water challenges that the region is facing into three parts, or “whammies,” Jayantha Obeysekera, a scientist with the South Florida Water Management District said.

The first is sea-level rise. Because of ocean currents and Miami's location, sea levels are rising in and around the city and Miami Beach faster than in most of the world.

The second problem facing South Florida is a vexing geological one. “Our underlying geology is like Swiss cheese,” said Obeysekera.

The solid ground under South Florida — Miami, Miami Beach, the Keys, and much of the rest of the peninsula — is mostly limestone made of compressed ancient reefs that are full of tiny holes. That means salty water is rising up through the ground itself, not just in the waters surrounding Florida.

The water could start intruding on drinking-water reservoirs (it already has in some areas) and killing off non-salt-tolerant vegetation, including shade-providing palm trees. It’s impossible to wall South Florida’s water out with levees or giant gates — as other cities have done — if the water rises up through the ground. When I asked one architect what the solution might be, she threw her hands up in the air.

Obeysekera said the third whammy, the effect of future storms, is still an unknown. The consequences of a warmer world on hurricane season are uncertain, but many scientists agree that we can expect storms to be more intense, which could mean higher storm surges and more rainfall.

The worst-case scenario drowns the peninsula

It’s only possible to plan so far ahead, said Jane Gilbert, the chief resilience officer for the City of Miami. Resilience officers in different cities face a variety of challenges, but for Gilbert in Miami, sea-level rise and the other challenges that come with it — like hurricane surges, housing affordability, and transportation through flooding neighborhoods — are top priorities.

Predictions for sea-level rise over the next 40 years show significant increases in sea level by 2060, likely between 13 and 34 inches. But beyond 40 years from now, the level of uncertainty is too high to know how much rise to expect, Gilbert said.

How sea-level rise could transform Miami

When geologists look back at the history of the Earth, they observe that sea-level rise often comes in “pulses” associated with the melting of ice sheets, which bring dramatic amounts of water in a very short time frame. If one of those pulses were to kick in, geologist Harold Wanless thinks it’s possibleFlorida could see between 10 and 30 feet of sea-level rise by the end of this century.

“Miami as we know it today — there’s virtually no scenario under which you can imagine it existing at the end of the century,” Goodell said. “It may be some smaller version of Miami that incorporates platform houses and floating structures.”

Miami is engineering to keep the water out

On one of Bruce Mowry’s first visits to Miami Beach, he saw an elderly couple holding hands and making their way through the floods, wearing black stovepipe boots with the water creeping up. He was shocked by the seriousness of the situation.

“They’re spending the end of their lives standing in water,” he said.

Mowry, now the city engineer for Miami Beach, agreed in 2013 to help Mayor Philip Levine — who paddled the floods in a kayak in campaign ads and is now running for governor in Florida — deal with tidal flooding.

Mowry and his team immediately started installing pumps that force water back into Biscayne Bay in parts of the city known to flood, shoring up at least some of the seawalls and putting valves in pipes to prevent water from flowing back up.

There are about 30 pumps installed so far, with up to 90 planned in total.

Along with pumps, Miami Beach added water-treatment stations so that the water being pumped into the bay is cleaner than the stuff that pools in the streets when storm drains get backed up.

"The solution in the near term in Miami is to build their way out of things. … But at a certain point, it becomes economically not feasible."

The pumps work (most of the time, at least). Levine was able to stand in Sunset Harbor, a neighborhood known for flooding, the next year during king tides and celebrate dry land.

“I told the mayor later, you’re damn lucky. If it had rained that day you would have been standing in water,” Mowry said.

Going from serious flooding one year to dry streets the next is impressive and shows it’s possible to do something about flooding, according to Mowry. But there are limits to technology in such a low-lying and vulnerable area.

Pumps may work for Miami Beach, a city that covers only 8 square miles. It would be impossible to use them throughout the whole peninsula. At a certain point, expending all the energy required to keep pumps running and to engineer water out from all sides might do more global harm than good in terms of fossil-fuel emissions, which trigger further climate change.

“I do think that the solution in the near term in Miami is to build their way out of things. … But at a certain point, it becomes economically not feasible,” said Goodell.

For now, Miami Beach has raised roads, with some several feet higher than the buildings they run past — meaning cars can get around safely even if sidewalks flood.

Revamping building codes to allow developers to build higher is another way to deal with the effects of sea-level rise. In a place like Miami Beach, there’s resistance to elevating structures and blocking views since everyone wants to see the beach, but that resistance is incompatible with making the adaptations needed.

As Susanne Torriente, the chief resilience officer for Miami Beach, explained, the city prioritizes certain actions with the knowledge that more changes will be needed in the future. It’s possible to raise roads and structures up to a point that might get the city to 2050 or 2060. By then, she said, “The data will hopefully be better and hopefully technology is better and solutions are better.”

When I drove into Sunset Harbor, pulling into a street parking spot behind a white Rolls Royce, flood-control measures seemed to still be working. I was a few hours away from high tide, but I found the first pump stations that had been installed in the city, and the ground was mostly dry.

Still, I was visiting during a remarkably “low” king tide — “nada,” as Pedraza had said about the same king tide in Shorecrest.

Miami Beach is working hard to confront its problem with sea-level rise head-on. But as many of the people working in South Florida acknowledge, it’s one thing to try to keep water off a small, well-funded island like Miami Beach; it’s quite another to keep it off an entire peninsula populated by millions.