Miami was built next to the ocean on purpose, and much of its development over the years has been aimed at keeping the city close to the water. But now the seas are rising, and city planners are thinking about how to hold the water out.

Miami Beach FL after a 1-meter sea level rise. Courtesy of Architecture 2030

Greg Hanscom puts the situation into perspective in a recent issue of the online journal Grist (see: "Miami vise: Rising seas put the squeeze on a sun-drenched beach town," by Greg Hanscom). Writes Hanscom: "It's a balmy, mid-November morning in Miami Beach, Fla., and I'm sitting at one of the cafe tables in front of the local Whole Foods, sipping a cup of coffee, and watching the tide come up. Oh, you can't see the ocean from here. The tide is gurgling up through the storm drains along the street … Pedestrians abandon the submerged sidewalks for high ground in the middle of the Alton Road, dodging rooster tails kicked up by passing vehicles. To get back across town, I'll have to wade through murk that comes almost to my knees."

Hanscom interviewed Miami architect Thorn Grafton, who descends from some of the earliest settlers to clear and develop the area. Writes Hanscom: "'My concern, short term, is that a storm surge is going to hit all the historic hotels on Ocean Drive,' Grafton says, 'and some of the building owners are going to use that as an opportunity to [tear down the old structures and] rebuild.' Longer term, he worries that rising seas will cut off the two low-lying causeways that currently provide access to the island."

Miami-Dade commissioners are thinking hard about the problem, reports the Miami Herald's "Naked Politics" blog (see: "Miami-Dade commissioners: We want county plans to consider sea-level rise," by Patricia Mazzei). "A broad discussion on the county's dilapidated water and sewer pipes began Tuesday with Commission Chairwoman Rebeca Sosa exhorting staff to consider rising sea levels 'in every detail' of the future development of infrastructure," the Herald reports. "We have seen what is happening in Miami-Dade County. We see that the state of Florida is placed on the map as one state that is in incredible danger because of the changes in climate and in weather," said Sosa. If planners don't consider the threat, said Sosa, "We will be misspending that money, because we will have to come back and we will have to fix the infrastructure."

But the details are going to be tricky. Local leaders have traveled to the Netherlands in search of ideas for protecting their low-lying region against ocean flooding, Hanscom notes. But Florida's porous limestone underpinnings make dikes a poor solution, he points out: "Geologists compare it to Swiss cheese. Build all the dikes and seawalls you like, they say: As the seas rise, the water will just seep in through the ground. Blocking the storm drains may slow it down some, but it's going to come regardless."

Where's the dry land going to be? Well, in November, volunteers from the High Water Line Project drew lines on the sidewalk to illustrate what the future could hold. The Weather Channel had the story (see: "How Far Will Sea Levels Rise? In Miami, They Drew Lines On The Pavement To Find Out," by Terrell Johnson).

"The lines, drawn with a chalk line marker you'd find at a baseball field, show how far the Atlantic Ocean and Biscayne Bay would encroach if sea levels rose by 3 feet and by 6 feet, reflecting optimistic (and pessimistic) forecasts for sea level rise in Miami by 2100," the Weather Channel reports. "Following maps based on sea level rise analysis by Climate Central, the volunteers laid down chalk through historic neighborhoods like Little Havana and right up to the doors of both American Airlines Arena, where the NBA's Miami Heat play, and Marlins Park, the home of baseball's Miami Marlins."