New York's Sea-Level Plan: Will It Play in Miami?

National Geographic Daily News - June 12, 2013 - Tim Folger

Mayor Michael Bloomberg's announcement yesterday of a $19.5 billion, multidecade plan to defend New York City against rising seas and severe storms illustrated two truths that resonate far beyond his home city.

First, as the time when we could prevent dangerous climate change slips away, the time for costly investments to protect ourselves has arrived. Second, for some cities, less well situated or less wealthy than New York, protection is going to be extremely challenging—and in some cases perhaps impossible ....

New York has taken the threat much more seriously than most American jurisdictions. At least one state, North Carolina, is actively ignoring the problem: The state legislature has refused to include realistic sea-level rise projections in its coastal planning policies.

Even with enlightened leadership, however, the sorts of engineering solutions proposed by Bloomberg won't work everywhere. Miami, for example, which tops the OECD report's list for cities with the most assets at risk, rests on a foundation of highly porous limestone. Seawater would flow unimpeded beneath any levee or storm surge barrier.

It's already contaminating Florida's underground water supply, and it regularly erupts from Miami's sewers during "king tides," when the sun and moon exert their most powerful tidal pull on Earth. The problem is only going to get worse: By the century's end large parts of Florida may be underwater.

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