Barring a rapid change in our nation's relationship to fossil fuels, every American within shouting distance of an ocean -- including all of us in the nation's capital -- will become de facto New Orleanians. Imagine a giant floodgate spanning the Potomac River just north of Mount Vernon, there to hold back the tsunami- like surge tide of the next great storm. Imagine the Mall, Reagan National Airport and much of Alexandria well below sea level, at the mercy of "trust-us-they'll-hold" levees maintained by the Army Corps of Engineers. Imagine the rest of Washington vulnerable to the winds of major hurricanes that churn across a hot and swollen Chesapeake Bay, its surface free of the once vast and buffering wetland grasses and "speed bump" islands that slow down storms.
Higher sea levels create other conditions that will only enhance hurricanes. In 1985, Hurricane Gloria made landfall north of New York Harbor. As a Category 2 storm, it could have had a serious surge tide. But it was a relative dud, causing only minor flooding. New York got lucky because the storm struck at maximum low tide, when the ocean had conveniently lowered itself a full five feet in relation to the land. Had Gloria arrived just six hours earlier or later, experts say, it would have been a monster, at least as destructive as the Great Hurricane of 1938 that killed 50 Long Islanders and caused billions in damage.
Adapting, of course, means committing fully to the New Orleans model. It means potentially thousands of miles of levees and floodwalls across much of the region. And that's just to handle the rising sea. For hurricane surge tides, [J. Court Stevenson] thinks the only solution might be to build a floodgate across the Potomac near Mount Vernon. It could be closed during periods of maximum danger, then reopened as the surge ebbs. He envisions another on the Patapsco River to protect Baltimore. The New York Academy of Sciences, meanwhile, has examined the idea of three such floodgates for New York City.
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