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New York Sea Level

Page history last edited by PBworks 13 years, 9 months ago

NASA Looks at Sea Level Rise, Hurricane Risks to New York City 10.24.06



New York City has been an area of concern during hurricane season for

many years because of the large population and logistics. More than 8

million people live in the city, and it has hundreds of miles of

coastline that are vulnerable to hurricane threats. Using computer

climate models, scientists at NASA have looked at rising sea levels

and hurricane storm surge and will report on them at a science

meeting this week.


Cynthia Rosenzweig and Vivien Gornitz are scientists on a team at

NASA's Goddard Institute for Space Studies (GISS) and Columbia

University, New York City, investigating future climate change

impacts in the metropolitan area. Gornitz and other NASA scientists

have been working with the New York City Department of Environmental

Protection (DEP) since 2004, by using computer models to simulate

future climates and sea level rise. Recently, computer modeling

studies have provided a more detailed picture of sea level rise

around New York by the 2050's.


During most of the twentieth century, sea levels around the world

have been steadily rising by 1.7 to 1.8 mm (~0.07 in) per year,

increasing to nearly 3 mm (0.12 in) per year within just the last

decade. Most of this rise in sea level comes from warming of the

world⤁s oceans and melting of mountain glaciers, which have receded

dramatically in many places since the early twentieth century. The

2001 report of the Intergovernmental Panel on Climate Change found

that a global warming of 1.4° to 5.8° C (2.5° -10.4° F) could

lead to a sea level rise of 0.09-0.88 meters (4 inches to 2.9 feet)

by 2100.


A study conducted by Columbia University scientists for the U.S.

Global Change Research Program in 2001 looked at several impacts of

climate change on the New York metropolitan area, including sea level

rise. The researchers projected a rise in sea level of 11.8 to 37.5

inches in New York City and 9.5 to 42.5 inches in the metropolitan

region by the 2080s.


"With sea level at these higher levels, flooding by major storms

would inundate many low-lying neighborhoods and shut down the entire

metropolitan transportation system with much greater frequency," said



With sea level rise, New York City faces an increased risk of

hurricane storm surge. Storm surge is an above normal rise in sea

level accompanying a hurricane. Hurricanes are categorized on the

Saffir-Simpson scale, from 1 to 5, with 5 being the strongest and

most destructive. The scale is used to give an estimate of the

potential property damage and flooding expected along the coast from

a hurricane landfall. Wind speed is the determining factor in the

scale, as storm surge values are highly dependent on the slope of the

continental shelf and the shape of the coastline, in the landfall



A recent study by Rosenzweig and Gornitz in 2005 and 2006 using the

GISS Atmosphere-Ocean Model global climate model for the

Intergovernmental Panel on Climate Change projects a sea level rise

of 15 to 19 inches by the 2050s in New York City. Adding as little as

1.5 feet of sea level rise by the 2050s to the surge for a category 3

hurricane on a worst-case track would cause extensive flooding in

many parts of the city. Areas potentially under water include the

Rockaways, Coney Island, much of southern Brooklyn and Queens,

portions of Long Island City, Astoria, Flushing Meadows-Corona Park,

Queens, lower Manhattan, and eastern Staten Island from Great Kills

Harbor north to the Verrazano Bridge. Gornitz will present these

findings at the annual meeting of the Geological Society of America

in Philadelphia during the week of Oct. 23.


To understand what hurricane storm surges would do to the city, surge

levels for hurricanes of categories 1 through 4 were calculated by

the U.S. Army Corps of Engineers for the 1995 Metro New York

Hurricane Transportation Study using NOAA⤁s SLOSH computer model.

SLOSH (Sea, Lake and Overland Surges from Hurricanes) is a

computerized model run by the National Hurricane Center to estimate

storm surge heights resulting from historical, hypothetical, or

predicted hurricanes by taking into account pressure; size, forward

speed, track and hurricane winds.


According to the 1995 study, a category three hurricane on a

worst-case track could create a surge of up to 25 feet at JFK

Airport, 21 feet at the Lincoln Tunnel entrance, 24 feet at the

Battery, and 16 feet at La Guardia Airport. These figures do not

include the effects of tides nor the additional heights of waves on

top of the surge. Some studies suggest that hurricane strengths may

intensify in most parts of the world as oceans become warmer.

However, how much more frequently they will occur is still highly



Hurricanes have hit New York City in the past. The strongest

hurricane was a category four storm at its peak in the Caribbean,

which made landfall at Jamaica Bay on Sept. 3, 1821 with a 13-foot

storm surge. It caused widespread flooding in lower Manhattan. The

"Long Island Express" or "Great Hurricane of 1938," a category three,

tracked across central Long Island and ripped into southern New

England on Sept. 21, 1938, killing nearly 700 people. The storm

pushed a 25-35 foot high wall of water ahead of it, sweeping away

protective barrier dunes and buildings.


The 1995 Transportation study was done to assess the vulnerability of

the city's transportation system to hurricane surges. The 2001

Columbia study was one of the regional studies for the U.S. National

Assessment of Climate Variability and Change; the recent study for

the NYC DEP was to evaluate potential climate change impacts,

including sea level rise, on the agency's mandated activities and



"This entire work is solutions oriented," said Rosenzweig. "It's

about helping NYC DEP and other New York City agencies make better

preparations for climate extremes of today, and changing extremes of

the future. The report will help us determine how can we do better

job now, as well as in the future."


Rob Gutro

Goddard Space Flight Center

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