Wake of the Flood

Shortly after I moved to New York last August the city was hit by an earthquake, a hurricane, and an October snowstorm. These kinds of things aren’t supposed to happen in the Big Apple (if I wanted to live in a disaster movie I could have moved to California).

But happen they did, causing many New Yorkers to joke about the End of Days—and some to prepare for them. That may be premature. There is no reason to think that earthquakes will become a frequent occurrence on the East Coast. Preparing for more floods, however, is a really good idea. (Snowstorms are likely to become less frequent, but heavy snowfalls may increase as our atmosphere warms, increasing its water-holding capacity. See Theo Spencer’s post on trying to ski without snow.)

Hurricane Irene caused extensive flooding, power outages, and property damage throughout the Eastern Seaboard and into Vermont, killing at least 44 people in 13 states. Many commentators called it a 100-year storm. New research shows that flooding like what we saw from Irene could become a much more regular occurrence as our climate changes and sea levels rise.

The study conducted by Ning Lin and Kerry Emauel of MIT with Michael Oppenheimer and Erik Vanmarcke of Princeton focused on the risk of flooding in New York City. The researchers simulated 5000 storms under historic climatic conditions to develop a flood risk baseline. They then simulated another 5000 storms under conditions expected if carbon pollution continues to accumulate in our atmosphere unchecked, changing our climate and raising sea levels. Their conclusion is well summarized by the headline in the MIT News story about the study: ‘Storm of the Century?’ Try ‘Storm of the Decade.’

Specifically, the study found that a storm surge of 5.7 feet or higher, which currently occurs an average of once every 100 years, would occur once every 3 to 20 years due to the effects of heat-trapping pollution. Given that the sea walls protecting lower Manhattan are only about 5 feet tall, this means the city has a lot of work to do if it is to minimize the damage.

Fortunately for New York, it has a leg up on most cities. Cynthia Rosenzweig of NASA and Columbia University has for many years been studying the risks that our changing climate poses to New York and developing recommendations on steps the city should take to prepare. And the City is listening. Mayor Bloomberg wrote the forward to a 2010 report she edited, which was published in the Annals of the New York Academy of Sciences.  New York’s subway system, the lifeblood of the city, is already taking steps to reduce the risk that its huge network of tunnels will flood during storms by, for example, raising some subway vents by six inches. The full preparedness plan could cost the cash-strapped transit system $15 billion according to Klaus Jacobs of Columbia.

New York has benefited from a unique partnership between its world-class research centers, home-grown philanthropies, and forward-looking City Hall, and it still has a long way to go. How well prepared is your city for the storm of the century to become the storm of the decade?