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In the ‘Magic City,’ Sea Level Rise Puts Assets

Most of our planet’s 7 billion people now live in cities. Historically these have been built near lakes, rivers and oceans — sources for food, water and transportation.

According to recent estimates from the United Nations, more people are moving into cities and by 2050, two out of three will be living in these urban centers. For the hundreds of millions living in coastal cities, the end of this century and beyond looks to bring significant existential challenges. This includes those residing in the South Florida megalopolis that extends from Miami to Palm Beach.

From my office window in Miami, I can see a fraction of the trillions of dollars invested in a super-infrastructure designed to make our city life more comfortable. But I can also see a menacing Atlantic Ocean, which already frequently inundates our streets with salt water, even on sunny days.

That’s one big reason why climate change is such a big concern. We can’t “move” entire cities like New York or Shanghai because sea level rise will soon be inundating them. Miami, specifically, is the top ranked city in the world in terms of assets at risk. It’s a city that’s indefensible against higher sea level because it sits on top of porous limestone.

No dike can be built to stop seawater from penetrating far inland, contaminating drinking water supplies and lifting the water table to the point of inundation along a very flat and low landscape. A higher water table also means any strong rainstorm yields urban and flash flooding with greater ease. Waves from distant storms in the Atlantic can send swells towards our coast that quickly erode beaches and take a bite out of coastal roadways. And the next time a hurricane strikes from the east, the storm surge will be higher and penetrate further inland.

There are no complete or immediate solutions to the surging seas’ effects upon South Florida. The City of Miami Beach is investing hundreds of millions of dollars for a series of pumps that have already been put to work during the annual King Tide to keep the streets dry. Important arteries in the city have been lifted two feet, at a significant cost. Building and zoning rules are being changed to insure new infrastructure may be more resilient.

Beyond Miami Beach, a four-county regional climate compact has settled on an expectation of 2 feet of sea level rise by the year 2060. Even though the rate of sea level rise is expected to accelerate in the second half of this century, local governments are not accounting for what might happen beyond 2060.

As I write this in 2015, there are dozens of new buildings in various phases of development along Miami’s coast. No one seems to be concerned about the long-term viability of these edifications nor the infrastructure that supports living in them. Insurance rates are still low relative to the risk (greatly subsidized by the government).

This won’t go on forever, probably not even into the late 21st century. Eventually, hundreds of thousands of people who thought their families could remain comfortably anchored in their Magic City homes will have to consider a Plan B, especially for their children and grandchildren, due to sea level rise caused by global warming.