NASA Looks at Sea Level Rise, Hurricane Risks to New York City 10.24.06
<http://www.nasa.gov/mission_pages/hurricanes/archives/2006/sealevel_nyc.html>
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
worldâ¤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
Gornitz.
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
region.
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 NOAAâ¤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
uncertain.
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
infrastructure.
"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
Find this article at:
http://www.nasa.gov/mission_pages/hurricanes/archives/2006/sealevel_nyc.html
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Working at the Crossroads of Environmental and Human Rights since 1990
PO Box 7941
Missoula Montana 59807
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