October
25, 2006
NASA LOOKS AT SEA LEVEL RISE,
HURRICANE RISKS TO NEW YORK CITY
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 (DEP) of Environmental Protection 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 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
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
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."
For
more information
and images, visit:
http://www.nasa.gov/mission_pages/hurricanes/archives/2006/sealevel_nyc.html
For
more
information on the NOAA SLOSH hurricane model, visit:
http://hurricanes.noaa.gov/prepare/slosh.htm
For
more
information about the Saffir-Simpson scale, visit:
http://www.nhc.noaa.gov/aboutsshs.shtml
For
more
information about the Geological Society of America, visit:
http://www.geosociety.org/
##
Contact:
Rob
Gutro
NASA Goddard
Space Flight Center
301-286-4044
robert.j.gutro@nasa.gov
This
text is derived from:
http://www.nasa.gov/mission_pages/hurricanes/archives/2006/sealevel_nyc.html