Friday, August 26, 2011

New York City, Hurricanes, and Global Warming

Heidi Cullen has written an interesting book titled The Weather of the Future: Heat Waves, Extreme Storms, and Other Scenes from a Climate-Changed Planet. She devotes the first part of the book to a discussion of climate modeling in order to convince any doubters that change is truly on its way. The majority of the book covers several locations around the globe in an assessment of the local effects of climate change. This is actually the more interesting part of the book. It seems an appropriate time to recall that one of the locations Cullen investigated was the city of New York.

The future anticipated for New York consists of hotter weather and more severe storms. The increase in temperature will mainly affect the power grid with the anticipated overloads causing more frequent brown-outs. This seems like a likely location for some infrastructure investment.

New York is hampered by an archaic drainage system. Flooding is already a common occurrence during heavy rains. New York City has a single sewer system for sanitary waste and for storm drainage. A heavy rain can overload the system and cause waste water to be expelled into the rivers. A very heavy rain can cause the water to back up and cause flooding in the city.

The nightmare scenario that Cullen considers is a category 3 hurricane that takes direct aim at the city, an occurrence that she views as inevitable. New York is extremely vulnerable in such an event. She provides a list of locations susceptible to flooding because of the elevation: Canal Street Subway station +8.7 feet, Christopher Street Station -15 feet, Holland Tunnel entrance (NY) +9.5 feet, and La Guardia Airport +6.8 feet.

“According to a 1995 study by the U. S. Corps of Engineers, a category 3 hurricane in New York would create a surge up to 16 feet at La Guardia airport, 21 feet at the Lincoln Tunnel entrance, 24 feet at the Battery Tunnel, and 25 feet at John F. Kennedy International Airport. And that is with sea level measurements of 1995. The impact could be even greater if the storm hit at high tide....The Army Corps of Engineers estimates that as many as 3 million people would need to be evacuated from New York City.”

Cullen tells us that there have only been two direct hits on the city in recent history:

“....the Great September Gale of 1815, and a storm that came on September 3, 1821, and made landfall at Jamaica Bay. Both were category 3 storms and both did extensive damage. With wide-spread flooding in lower Manhattan as far north as Canal Street, the 1821 hurricane set the record for the highest storm surge in Manhattan—nearly 13 feet.”

One can understand why New York has responded so quickly and so forcefully to the approaching Irene. It is a massive storm that may not approach as a category 3, but if the surge doesn’t cause flooding, the heavy rains certainly will.

The lesson that emerges from reading Cullen’s various scenarios is that climate change is going to require massive investments in infrastructure. New York City’s issues are perhaps the easiest to visualize. Consider this little nugget that Cullen provided.

“New York City has regulators. So when the tide goes out, the pipes—the storm sewers— are exposed and the water flows out of them and into the river. But when the tide comes in and there’s flooding, the regulators shut, or else you would have all the river water flooding New York City. Now if there’s a sea level rise to where those regulators are always shut, there is no place for any storm water to go, and it will all spill onto the street...”

That would seem to be a very short-sighted manner in which to set up the drainage for a city. Much of New York’s infrastructure is a century old. Do people think it can last forever?

If anyone wonders where the jobs are going to come from, think about how many workers it would take to make New York storm-safe. And then consider how many other locations will have their unique issues to deal with. There is plenty of work—we just need to figure out how to make it happen.

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