How to protect New York from disaster

September 11, 2012
Mireya Navarro's article about the risk of natural disaster -- flooding -- in New York.

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Today, September 11, is a day that all New Yorkers become hyper-aware of tail risk — of some monstrous and tragic disaster appearing out of nowhere to devastate our city. And so it’s interesting that the NYT has decided to splash across its front page today Mireya Navarro’s article about the risk of natural disaster — flooding — in New York.

Beyond the article’s publication date, Navarro doesn’t belabor the point. But in terms of the amount of death and destruction caused, a nasty storm hitting New York City could actually be significantly worse than 9/11. Ask anybody in the insurance industry: a hurricane hitting New York straight-on is the kind of thing which reinsurance nightmares are made of. And as sea levels rise in coming decades, the risks will become much worse: remember, it’s flooding from storm surges which causes the real devastation, rather than simply things blowing over in high winds.

So, what can or should be done? One option is to basically attempt to wall New York City off from the Atlantic Ocean:

A 2004 study by Mr. Hill and the Storm Surge Research Group at Stony Brook recommended installing movable barriers at the upper end of the East River, near the Throgs Neck Bridge; under the Verrazano-Narrows Bridge; and at the mouth of the Arthur Kill, between Staten Island and New Jersey. During hurricanes and northeasters, closing the barriers would block a huge tide from flooding Manhattan and parts of the Bronx, Brooklyn, Queens, Staten Island and New Jersey, they said.

Needless to say, this solution is insanely expensive: the stated price tag right now is $10 billion — well over $1,000 per New Yorker — and I’m sure that if such a project ever happened, the final cost would be much higher. And such barriers don’t last particularly long, either. London built the Thames Barrier in 1984, and there’s already talk about when and how it should be replaced. And building a single barrier across the Thames is conceptually and practically a great deal simpler than trying to hold back the many different ways in which the island of Manhattan is exposed to the water.

What’s more, there’s an environmental cost associated with barriers, as well as a financial cost. Which cuts against the kind of things which New York has been doing. They’re smaller, and much less robust. But they improve the environment, rather than making it worse. And they’re relatively cheap. For instance: installing more green roofs to absorb rainwater. Expanding wetlands, which can dampen a surging tide, even in highly-urban places like Brooklyn Bridge Park. Even “sidewalk bioswales”. (I’m a little bit unclear myself on exactly what those are, but they sound very green.)

Adam Freed, the outgoing deputy director of New York’s Office of Long-Term Planning and Sustainability, talks about making “a million small changes”, while always bearing in mind that “you can’t make a climate-proof city”. That’s a timely idea: we can’t make New York risk-free, and it’s not clear that it would make sense to do so even if we could. After all, as we all learned 11 years ago today, it’s impossible to protect against each and every source of possible devastation.

Other cities have similar ideas:

In Chicago, new bike lanes and parking spaces are made of permeable pavement that allows rainwater to filter through it. Charlotte, N.C., and Cedar Falls, Iowa, are restricting development in flood plains. Maryland is pressing shoreline property owners to plant marshland instead of building retaining walls.

Still, all of this green development does feel decidedly insufficient in comparison to the enormous risks that New York is facing. I like the idea of a “resilience strategy”, but there are still a lot of binary outcomes here, especially when it comes to tunnels. Either tunnels flood or they don’t — and if they do, the consequences can be really, really nasty. Imagine a big flood which took out all of the subway and road tunnels into Manhattan, or even just the subway tunnels across New York Bay as well as the Holland Tunnel. As such a flood becomes more likely, the cost of protecting against it with some big engineering work — insofar as such a thing is possible — becomes increasingly justifiable.

And this is just depressing:

Consolidated Edison, the utility that supplies electricity to most of the city, estimates that adaptations like installing submersible switches and moving high-voltage transformers above ground level would cost at least $250 million. Lacking the means, it is making gradual adjustments, with about $24 million spent in flood zones since 2007.

Lacking the means? What is that supposed to mean? New York City has a credit rating of Aa1 from Moody’s; ConEd has a crediting rating of A3. Interest rates are at all-time lows. There has never been a better time to invest a modest $250 million in helping to ensure that New York can continue to have power in the event of a storm. Doing lots of small things is all well and good, and I’m not convinced that the huge things are necessarily worthwhile — or even, in the case of moving people to higher ground, even possible. But the medium-sized things? Those should be a no-brainer right now.


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