New Orleans won't be the only U.S. city grappling with flooding
over the next century. Rising sea levels and sinking coastal lands
mean cities all along U.S. coastlines face a predicted rise in
ocean water levels. The increase could be from a manageable few
inches to a catastrophic several feet.
Nowhere to Run
Among the U.S. cities facing a threat from rising sea levels, Palm
Beach, the Riviera of the U.S., won't be forsaken. Property values
between Palm Beach and Miami are estimated at a trillion dollars.
No one is about to abandon the area. Rather, say planners and
scientists, Florida will seek massive public works to hold back the
sea. Projects that, while spread out over a longer period than the
reconstruction of the New Orleans levees, will likely dwarf that
$10 billion cost.
"We're humans. We want everything to be kept the same," says Dan
Trescott, principal planner for the Ft. Myers-based Southwest
Florida Regional Planning Council.
With a grant from the Environmental Protection Agency (EPA), that
council late last year completed Florida's first attempt to tackle
sea-level rise from an urban planning slant. The study found that
nearly 97% of developed Palm Beach County within 1,000 feet of the
ocean sits 0 to 10 feet above sea level. Because South Florida's
tides can add 5 feet to normal sea level, nearly all of the
county's 56,000-plus coastal acres would flood regularly if seas
rise 5 feet. A less severe rise would leave higher ground dry but
inundate lower areas and open them to more frequent storm flooding.
The most vulnerable places include not only many of Palm Beach's
mansions but also West Palm Beach, Boca Raton, Jupiter, and 20
So, the planners concluded, Florida is likely to pull out all the
stops to hold back the sea in Palm Beach County. But even that may
not be enough. "I just don't think there's enough money or fill to
hold it all back, myself," Trescott warns.
Other recent EPA-funded sea-level-rise studies have led to similar
conclusions. A 2004 study of the Boston area, for example, found
that "the total property and contents damages and emergency
services … over the next 100 years could range from $20
billion to $94 billion if there are no adaptive responses except
rebuilding after floods."
There's not enough money or fill to hold
back the sea
For residents and policy makers alike, the importance of these
studies depends enormously on two related processes: how much sea
levels may rise globally, and how much coastal land sinks
regionally, a process known as subsidence. The combination leads to
relative sea-level rise, which is the figure that counts for local
There is little debate about why seas are rising. The main culprits
are the expansion of water as it warms and the melt-off of polar
ice, phenomena both tied to global warming. How far and how fast
seas will rise is much murkier. The U.N.-backed Intergovernmental
Panel on Climate Change says that most studies predict a global
sea-level rise of 4 to 35 inches by 2100. Research released this
spring concludes that ice loss in Greenland and Antarctica has
accelerated. And while people tend to think of climatic change as
slow and predictable, the Earth's geological history suggests
sea-level fluctuations are "never a smooth story" and have a
potential for rapid change, according to University of Miami
geologist Hal Wanless.
Meanwhile, much of the East and Gulf coasts are sinking. This is
caused by the diversion or drying up of rivers that once moved soil
from inland to coast, wave-driven erosion, and withdrawal of
groundwater or oil, spurring underground collapses. The rate of
subsidence varies, with Galveston, New Orleans, and parts of North
Carolina among the coast's fastest-sinking areas. Seas are rising
about 3 feet per century along the Louisiana coast, according to
the EPA. Seas have risen more than 2 feet in Galveston since 1900,
Wanless says. In South Florida, the rise has equaled about 9 inches
since 1930. For Palm Beach, The Treasure Coast planners estimated a
90% chance of seas rising 10.4 inches and a 50% chance of seas
rising 19.8 inches during the next century.
One underlying result of sea-level rise is that 80% to 90% of U.S.
beaches are eroding, notes Florida International University
professor Stephen Leatherman, otherwise known as "Dr. Beach," in
his 2001 book Sea Level Rise: History and Consequences. But beach
erosion, which has many causes, is rarely tied to sea-level rise in
public debates. And the issue has to date mostly eluded public
interest. That's just now starting to change, say planners and
scientists. "The political system is not designed to look long
term, so you can hardly get anyone at the local level to even
consider it," Trescott says. "But I think this is the beginning of
Today, a narrow dune separates low-lying homes from the
encroaching sea near Galveston, Texas, which is among the coast's
fastest-sinking land areas. In relation to the land, the sea level
near Galveston has risen more than 2 feet since 1900.
The Treasure Coast sea-level rise report is the first of several
that will soon document Florida's vulnerability to sea-level rise
along its entire coast. This spring, Miami-Dade County created a
Climate Change Advisory Task Force aimed in part at advising the
county commission on "adaptation measures to be taken in response
to the challenge of global warming." Other coastal cities starting
to incorporate sea-level rise into their plans range from Medford,
Mass., to Olympia and Seattle in Washington, says Susan Ode,
outreach officer for the ICLEI USA office of Local Governments for
Sustainability. "Especially on the coasts, they are starting to
understand that there are just things we must do," Ode says. "There
isn't really the luxury of waiting."
Coastal cities have three main options as the waters rise. They can
uproot and retreat; raise their elevation; or build levees, dikes,
and other hardened engineering structures to keep the water out.
Retreat is probably the best option for sparsely populated regions.
But, with 13 of the world's 20 largest cities located on the coast
— and 53% of the U.S. population living in counties that
border the oceans or Great Lakes — that's more the exception
than the norm. Communities will likely turn to renourishing,
filling, elevating, and armoring instead.
Cities considering elevating will not only have to raise houses (or
raise currently elevated homes higher) but also elevate roads,
retail strips, sewer pipes, power substations, and water-treatment
facilities, Trescott notes. At the very least, that will involve
massive amounts of fill. Ironically, in southeast Florida, "We're
having a fill crisis now just trying to deal with the development
level," Trescott notes.
Dikes, breakwaters, revetments, bulkheads, floodwalls, and other
shore stabilization and protection measures are also expensive and
energy-consuming to build. A seminal 1991 study on sea-level rise,
"Greenhouse Effect and Sea Level Rise: The Cost of Holding Back the
Sea," estimated that it would cost $270 to $475 billion to armor
the entire U.S. coast against a sea-level rise of 1 meter, or about
3.2 feet. But that was with no future development, and today that
estimate seems exceptionally low. Yet, the study noted, without any
such protection, "a one-meter rise in sea level would inundate
14,000 square miles," half of it today's wetlands, half of it dry
With much of the East and Gulf coasts at or barely above sea
level, more and more communities will have to rely on seawalls to
help stem rising sea levels.
Without a firm grasp on the severity of the coming sea-level rise,
perhaps the best option is for communities and residents to tailor
future development. Scholars have imagined a range of scenarios in
which building and zoning laws could be tweaked. For example, for
barrier islands, which tend to migrate landward, "governments might
create a system of transferable development rights in which one
could fill and build on a bay-side lot, provided that an equally
large structure on the ocean side was removed," writes Jim Titus, a
Maryland lawyer and national expert on sea-level rise, in a 1991
paper that examined the impact of sea-level rise on a New Jersey
According to researchers, 80% to 90% of U.S. beaches are
eroding, requiring beach improvement efforts, such as this berm
restoration in Pensacola Beach, Fla.
As for private interests, Trescott says he is skeptical that
builders and developers will ever make sea-level rise a
consideration, because they are short-term investors in property.
But Titus isn't so sure. Hurricane safeguards have become a selling
point today for coastal homes. So might planning for sea-level rise
become a development's selling point, he says. He suggests, for
example, setting aside beachfront land that is particularly
vulnerable to erosion and orienting streets perpendicular to this
land. The goal: to prevent an entire street of homes from being
wiped out as the seas rise.
"The first step is get away from a situation in which real estate
agents and builders and developers feel like they have to deny the
situation to sell a house," he says. — Aaron
Green Building Gains Ground in Gulf
Concern for hazards released by flooding, plus rising energy
costs, stirs green building interest
When New Orleans architect and green building advocate Dan
Weiner happened into a church a few months after Hurricane Katrina,
members proudly showed him all their rebuilding achievements.
He admired their work — until the fumes in the daycare nearly
knocked him down. "They used toxic, off-gassing adhesive and paint
to get the school open quickly, and they were sticking children in
there," he says.
The experience illustrates the challenge that Weiner and others in
the green or "sustainable" building community face in New Orleans.
The city's massive rebuilding needs offer a one-of-a-kind
opportunity to put into place the ideas of green building on a
scale out of the reach of other built environments. But residents
trying to get back into their homes and businesses as quickly as
possible may lack the knowledge, money, or access to expertise to
pursue green techniques. "There's such an urgency to get back into
buildings that you may make decisions to your own detriment," says
Weiner, a board member of the Green Project, a New Orleans-based
group working to recycle construction materials from damaged
FEMA workers inspect lead paint peeling off a flooded wall.
Such perils have come into the spotlight after Katrina, prompting
green building advocates to push for rebuilding with fewer
Green building uses techniques and materials that raise energy
efficiency, pose no threat to human health, and are recycled or
come from environmentally friendly sources. After years of steady
growth, it has entered the mainstream, helped by a rise in energy
costs. A 2005 survey by McGraw-Hill Construction and the National
Association of Home Builders predicted the $7.4 billion industry
will go from its current 2% market share to at least $19 billion
and a 5% market share by 2010.
The potential for New Orleans to serve as a kind of test city for
green concepts has drawn the attention of both local and national
organizations. Santa Monica-based Global Green USA is one of
several with active programs in the city. As Monica Gilchrist, a
staffer with Global Green USA, puts it, when rebuilding New Orleans
"why not do it better? Why not do it more energy efficiently and
Katrina paved the way for green techniques not only physically but
also psychologically, advocates say. Already socked with increased
natural gas costs, residents are facing electricity rate hikes of
as much as 140% as local utility Entergy seeks to pay for restoring
power lines and production, says Forest Bradley-Wright, with the
New Orleans-based Alliance for Affordable Energy. "People are
seeing astounding utility bills, and that makes them receptive to
these types of opportunities," he explains.
There are some big hurdles, however. For starters, the city's "very
old building stock," as Bradley-Wright puts it, makes incorporating
green techniques and materials in rebuilding a unique challenge
— at least at the sophisticated level possible with new
construction. That said, the age of the city's homes make them
ideal for realizing another green priority: building products
recycling. The Green Project has already dismantled six homes and
"skimmed" dozens more for reusable scrap, much of it otherwise
unobtainable century-old wide-plank cypress or heart pine,
according to Weiner.
But the bigger challenges may be education and money. People may
not know, for example, that they can buy low-VOC (volatile organic
compound) paint, now a standard product offered by big paint makers
such as Sherwin-Williams, Weiner says. And though green products
are worth it in the long term, they are often more expensive up
Still, advocates are cautiously optimistic. "What I hear time and
time again from residents is that New Orleans has been behind the
curve," Gilchrist says. "This is an opportunity to catapult it to
the head of the pack." — A.H.