New interactive map shows effects of sea level rise on Charleston 

Here Comes the Ocean

Need a little doom and gloom to balance out the bliss of summer on the coast? Check out the new interactive map of coastal flooding projections from Climate Central, a non-profit group focusing on global climate change and sea level rise.

If the worldwide average high tide rises two feet above current levels, Colonial Lake could spill over into the surrounding neighborhood streets every day at high tide. At four feet above current high tide levels, beachgoers face standing water while driving on Folly Road. At five feet, the northern end of Park Circle becomes waterfront property.

The map incorporates data from three South Carolina tide stations, along with prediction models for climate change and laser-based elevation data to give down-to-the-block visualizations of how rising tides could affect coastal communities. Using a slider on the left side of the screen, you can see the effects of high tide in scenarios ranging from a 1-foot to a 10-foot rise.

Playing with the sea level slider while zoomed in on your home or place of business can be either a meditative practice in detachment from material possessions or a spark to inspire preparation and activism, depending on your temperament. Ben Strauss, lead researcher on the Climate Central map project, hopes for the latter.

"More than 800 square miles of land lie less than four feet above the high tide line in South Carolina," Strauss and other researchers write in a report accompanying the map. "Some $24 billion in property value and 54,000 homes — mostly in Charleston and Beaufort counties — sit on this area." The report also notes that, assuming a 4-foot rise in water level, about one in six homes are threatened in the city of Charleston.

The report, released in July, is largely built on a scenario in which global sea levels rise an average of 4 feet in the next 100 years, roughly in line with a projection made by the National Oceanic and Atmospheric Administration (NOAA).

NOAA has made broad-ranging predictions on how much the global average sea level will rise in the next 100 years, from 1 foot (if the level only continues to change at its current rate) to 7 feet (if, as feared, melting ice caps and expanding hot water cause the level to go up exponentially). The change will likely be noticeable even within 50 years, with the most dire prediction by NOAA putting high tide 2.28 feet above 2012 levels in 2062.

click to enlarge Workers operate a tunnel boring machine below the Market Street project - PHOTOS BY CAMERON POLLARD/CITY OF CHARLESTON MEDIA RELATIONS & PUBLIC INFORMATION
  • Photos by Cameron Pollard/City of Charleston Media Relations & Public Information
  • Workers operate a tunnel boring machine below the Market Street project

So, what to do in a low-lying city by the ocean? Activist groups including the Southern Alliance for Clean Energy and the S.C. Small Business Chamber of Commerce have been pressing the governments of coastal towns to start planning for a rising ocean. Laura Cabiness, director of Charleston's Department of Public Service, has a few ideas.

For starters, she says, the city is looking to form a citizen task force on sea level rise by the end of the year. Cabiness mentioned the idea during a City Paper interview in April, and she says her office has heard from a few people so far but is looking for a broader cross section. "We're looking for a wide group of people: businesspeople, representatives from residential neighborhoods, somebody hopefully from the academic community here, engineers, developers, and the utility companies. The goal is just to create a dialogue and try to capture the most pressing issues of climate change with sea-level rise issues," Cabiness says.

Cabiness and the Public Service Department will present another, more concrete idea for dealing with a watery future at the next City Council meeting on Aug. 19. Currently, all new construction in designated flood hazard areas must have the first floor elevated to the height of the 100-year flood mark — that is, a flood height that has a 1 percent chance of occurring in any given year. In Charleston's flood zones, that mark can range from 9 to 12 feet in height. Under the proposed ordinance, all new buildings in the flood hazard areas would have to have their first floors built an entire foot above the 100-year mark.

"I think it's important that cities and coastal communities are aware that the science is pretty definitive that seas are rising about one foot every 100 years," Cabiness says. "The sea level is going to rise, and there are certain things that are not real costly, like adding a foot of freeboard to new structures, that might add a little safety."

Barre Street flooded near its intersection with Wentworth Street during the King Tide Sunday night. - COURTESY OF CHRIS CARNEVALE
  • Courtesy of Chris Carnevale
  • Barre Street flooded near its intersection with Wentworth Street during the King Tide Sunday night.

The city's biggest anti-flooding effort to date has been its series of drainage improvement projects, which have been going on since roughly when Mayor Joseph P. Riley Jr. took office in 1975. According to Cabiness, the city has spent about $75 million on drainage improvements in the last 25 years. Massive drainage tunnels and pump stations are currently being installed under the City Market and the intersection of Spring and Fishburne streets, with the latter project expected to be complete by 2020. At the Market, Cabiness says residents can expect crews to finish up underground in the next nine months and begin working on surface-level drainage improvements.

South Carolina is the 14th coastal state that Climate Central has mapped, and while some cities like Charleston are planning for a rise in the ocean level, state government has resisted some efforts to slow the rising tide. The state recently joined a lawsuit against the EPA to stop the enforcement of new limits on carbon dioxide emissions at power plants. Opponents of the new rule have said that it will drive up the costs of utilities.

One activist who has been trying to stem the rising tide is Chris Carnevale, coastal climate and energy coordinator for the Southern Alliance for Clean Energy. Last Sunday, Carnevale walked around with a camera in Harleston Village to document a phenomenon known as the King Tide, an exceptionally high tide that can reach about 2 feet above the normal high-tide mark. In what could be a glimpse of the future as ocean levels continue to rise, water can sometimes be seen gurgling up through manholes and storm drains.

click to enlarge Lowering down into the drainage pipe project downtown - PHOTOS BY CAMERON POLLARD/CITY OF CHARLESTON MEDIA RELATIONS & PUBLIC INFORMATION
  • Photos by Cameron Pollard/City of Charleston Media Relations & Public Information
  • Lowering down into the drainage pipe project downtown

At a recent EPA hearing on new carbon pollution limits for power plants, Carnevale testified about the damage that rising tides could have on the Charleston area.

"Charleston is a place of significant cultural and historical heritage, but the impacts of climate change — such as sea level rise and ocean acidification — threaten our way of life and our connection to past generations," Carnevale said.

Strauss, the lead researcher on Climate Central's South Carolina study, says he doesn't have the answers for local governments trying to prepare for rising tides. He just wants to provide the data.

"We do think it's important for people to look at this closely," Strauss says. "Otherwise they're in store for a big surprise and a lot of pain."

To see how your home or business will fare during various sea-rise scenarios, visit the interactive map at sealevel.climatecentral.org.


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