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Global
warming = rising sea levels, more storms
Future
extreme weather could cause billions in damage to region
By Brian Fitzgerald
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Flooding in October 1996 caused the Emerald Necklace’s Leverett Pond in Brookline to overflow its banks. Photo courtesy of the Massachusetts Emergency Management Agency |
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On October 21, 1996, 10.8 inches of rain — over a month’s
worth — fell on Boston in one day. The precipitation, “more
than what Noah saw,” commented an official from the Federal Emergency
Management Agency (FEMA), caused the city’s Muddy River to overflow
and run down the MBTA D Line into the subway at the Longwood station tunnel.
Overnight, the water level in the underground Green Line stations rose
higher and higher — at the Kenmore station, all the way up to the
ticket booth. Service was seriously interrupted for weeks and the damage
was estimated at $60 million for the MBTA alone.
So, six and a half years later, when two BU geographers sought to demonstrate
the consequences of climate variability on the city of Boston, they looked
into the past to paint a picture of the future. At a conference in Denver
last month, they presented slides of the flooded Longwood and Kenmore
stations.
February’s annual meeting of the American Association for the Advancement
of Science provided the perfect opportunity for a team of civil engineering
and geography professors and graduate students from BU, Tufts, and the
University of Maryland to discuss the impact of climate change on the
Boston area. Global warming is expected to result in the rise of sea levels,
and cause more extreme weather events, including floods and heat waves.
The team’s research was funded by a $900,000 grant from the Environmental
Protection Agency to study how climate change will affect the critical
services and systems that make up the infrastructure in Boston and 100
surrounding communities. The researchers examined local flood data, the
impact of rising sea levels, and the continuing construction of buildings
along Boston’s North Shore and South Shore.
Their research shows that over the next century, damage to residential,
commercial, and industrial buildings and their contents in Boston and
nearby communities (an area stretching from Ipswich to Duxbury) could
exceed $20 billion, depending on how municipalities respond to the consequent
strains on their infrastructure. Costs could run as high as $94 billion,
if weather conditions are more severe than expected.
“And when we consider the damage to infrastructure, we tend to think
about it in terms of how much money it takes to rebuild it,” says
William Anderson, a CAS geography professor. “But what’s also
important to remember are the related costs to the public. The commuters
who had to take shuttle buses after the 1996 storm were inconvenienced
for a long time.” He says that it’s also necessary to take
into account the work hours lost to traffic jams caused by buses bringing
T customers to Green Line stops. This practice continued at intervals
for over a year, until the “drowned” signal system was replaced
by temporary signals. There were even further delays when a permanent
system was installed.
In addition, the storm canceled the Head of the Charles rowing competition
for the first time, flooded the Museum of Fine Arts, cut power in some
areas, and forced cancellations of classes, workdays, and sporting events.
Recurring floods
When the BU researchers wanted to use another example of an extreme storm
that paralyzed the area, they didn’t have to look very far. A deluge
in June 1998 wasn’t of biblical proportions, but was serious enough
to cause sewer overflows in Arlington, Cambridge, Canton, Medford, Newton,
Norwood, Roslindale, Weymouth, and Winchester. They showed a slide of
a flooded Willow Street in Roslindale, an area that is still recovering
from the 1996 storm. Then it happened again: four months later about 300
homes and businesses in the South End were inundated with several feet
of water and sewage. “We expect to see much more of these storms
because of global warming,” says Pablo Suarez (GRS’05), a
doctoral candidate in the department of geography and a research assistant
at the GRS Center for Energy and Environmental Studies.
Most scientists say that burning oil and coal has led to the buildup of
carbon dioxide in the atmosphere, which acts like a greenhouse roof, trapping
heat on the earth’s surface. They also assert that global warming
will result in more frequent and more intense storms, along with sea levels
higher by about a foot in the next century because of melting glaciers
and polar ice caps and thermal expansion of the ocean.
As part of efforts to protect life and property from flooding, FEMA has
mapped out a “100-year floodplain” throughout the country,
estimating the amount of coastal area that would be flooded by a storm
likely to be so substantial that it occurs only an average of once every
100 years. It also mapped out a 500-year floodplain. “Because of
rising sea levels, the same size wave that normally would swamp the 100-year
floodplain in Boston will soon become high enough to overtake the 500-year
floodplain,” says Paul Kirshen, a civil and environmental engineering
research professor at Tufts. “Sea level rise will have a drastic
impact on metropolitan Boston and other similar coastal cities if steps
aren’t taken to address this issue.”
The researchers presented three possible scenarios of how Boston could
respond to the change in sea level, and estimated both the cost of the
response and the cost of repairing storm damage: the “Ride-It-Out”
scenario, the “Build-Your-Way-Out” approach, and the “Green”
option. The first would mean that over the next century, area cities and
towns would continue developing in flood plains as it does now. “Riding
it out, not doing anything extraordinary until we are faced with a crisis,
would make additional infrastructure vulnerable,” says Anderson.
Municipalities would repair storm damage as it occurs to return buildings
to their original condition, which would cost $20 billion. The size of
the areas flooded will more than triple over the next 100 years in this
scenario. If Boston properties are damaged by more storms than the team
estimates, the total property and emergency costs could reach $94 billion.
The Build-Your-Way-Out option would also allow the current development
to continue without flood-proofing buildings, but would mean, says Anderson,
that after a second storm at the level of a 100-year storm, “Boston
would construct hurricane barriers and seawalls to protect coastal development.”
Damages from this scenario would be “only” $5.9 billion over
the next 100 years. However, construction of the necessary structures,
with the additional costs of building dams and drainage systems, could
cost up to $3.5 billion, and maintenance costs will be high.
A sensible scenario
The Green approach, Anderson says, “is a planned adaptation strategy
that would be much better for the environment.” All new development
in the 100-year and 500-year floodplains would be required to be totally
flood-proof, along with currently existing homes and commercial and industrial
buildings before being sold. Retrofitting homes would cost between $3,500
and $17,000 each. The Green alternative calls for spending $1.8 billion
for flood-proofing, but damages would decrease to $4.7 billion.
“The Green scenario would require more political awareness, and
that will be difficult to attain,” says Suarez. Anderson agrees.
“The idea of restricting the activities of developers will be met
with resistance,” he says. “Some policy-makers are generally
only concerned with the short-term horizon.”
Kirshen says that it is imperative that governments in the metropolitan
Boston area deal with the issue of the rising sea level and its impact
on coastal development as soon as possible. “It would be in the
region’s best interest to take this threat very seriously,”
he says. “As Ben Franklin once said, ‘An ounce of prevention
is worth a pound of cure.’ ”
21
March 2003
Boston University
Office of University Relations