11 Oct Rising Tides and The Future

Just want to share what remains on my mind as we look to the future and particularly infrastructure needs. -Mayor Billy

Area leaders fail to take serious action in face of rising threats from above and below

CHARLESTON POST AND COURIER / DOUG PARDUE AND TONY BARTELME / OCTOBER 11, 2021

The storm flew in from the ocean like an invading force, picking up fuel in the warmth of the Gulf Stream, then zeroing in on the South Carolina coast. The skies over Charleston darkened; the tides swelled. And then the clouds, laden with moisture, released their loads, one rain bomb after another, turning streets into rivers, turning swaths of South Carolina into disaster areas.

Welcome to the present, welcome to the future.

Last week’s storm unleashed a massive amount of water and disruption. Twenty-three inches fell on peninsular Charleston alone, roughly equivalent to 3.2 billion gallons of water — more than what pours over Niagara Falls in an hour. While public officials dubbed the storm a 1,000-year event, scientists warn that global warming will only send more rain bombs our way.

And these downpours come amid relentlessly rising seas. The sea level around Charleston already has risen a foot since the late 1800s, and global warming may add another 3 to 6 feet by the end of this century. With threats from above and below, Charleston is one of the most vulnerable metropolitan areas in the country to changes in a warming planet

But unlike leaders in New York and other low-lying municipalities, officials here have often faced threats from climate change with thundering silence. The city of Charleston and many neighboring municipalities lack comprehensive plans to address rising seas. While Charleston is on the front lines of climate change, the city’s Century V plan for the future doesn’t mention “sea rise” once.

But last week’s storm was a rain-soaked reminder: If you want a glimpse of Charleston’s future, you need only look up at the sky’s invading clouds and down at the rising floodwaters around your feet.

From below

Geologists have a saying: “The present is the key to the past, and the past is the key to the future.” On a decidedly drier morning earlier this year, Doug Marcy walked to the south end of Charleston’s cruise ship terminal to a contraption that told a story of Charleston’s past.

Marcy, a sea rise specialist with the National Oceanic and Atmospheric Administration’s Coastal Services Center in North Charleston, pointed to a metal pipe sunk vertically into the harbor. The pipe is one of the older tidal gauges in the country, in continuing use since 1921. With this marker, Marcy and other scientists know that the harbor’s sea level has risen more than one foot — 3 inches alone since Hurricane Hugo in 1989.

Part of that increase is from subsidence — land along the East Coast is sinking slowly because of the downward movements of tectonic plates. But the rest is from a rising ocean.

One foot doesn’t sound like much, but to scientists such as Marcy, the change is exciting and worrisome — exciting because geologists typically study changes that happen over the eons. “So when you can see it in a lifetime, it’s pretty amazing.”

It’s worrisome because of what it says about Charleston’s future. “Because we’re so low, it doesn’t take much of a vertical rise in the sea level to cover a large horizontal area.”

He said it’s helpful to think of the area around Charleston as a bathtub. A roughly 7-foot high tide fills this bathtub to the rim. Any additional water — whether from rain and wind, seasonal high tides or storm surges — causes the tub to overflow into the city.

Even before last week’s storm, king tides — seasonal tides caused by the moon’s gravitational pull — pushed water over that 7-foot lip: Though skies were blue, water recently lapped up by the gas pumps in the City Marina; it poured into the streets by the Market; it filled parking lots by Shem Creek. You could even taste the evidence: At the corner of America and Lee streets, tidal waters last month flooded the street and then left behind a white film of salt.

In 1957, the city had an average of 4.6 days of “nuisance flooding.” The city now has about 30 days. These routine floods, Marcy said, “are the canary in the coal mine.”

From above

Since 1921, when scientists began continuous measurements at the Charleston gauge, global temperatures have risen more than 1 degree. It’s another small increase with huge ramifications: Warmer air holds more moisture. When water vapor condenses and falls as rain, it releases energy in the form of heat. This adds even more fuel to storms, creating the kinds of torrents we saw last week.

The Southeast already has experienced a 27 percent increase in the number of downpours since 1958, a recent study revealed.

“Right now in Charleston you already get torrential rains,” said Kenneth Kunkel, a NOAA scientist in Asheville and author of that downpour study. “The key point is as we warm, you’ll have fuel to make these storms all that much greater.”

Andra Reed, a Penn State meteorologist, added that one severe event doesn’t prove anything about climate change but “we do know that Joaquin was able to intensify rapidly over extremely warm sea surface temperatures in the Atlantic.” As Joaquin strengthened, the atmosphere above filled with ever-greater amounts of moisture and then unleashed it over the Carolinas, she said.

Rising seas and temperatures are forcing meteorologists to rethink their assumptions of what’s normal. Reed co-authored a study that looked at New York’s history of torrential rains and floods. By examining microorganisms left behind in sediment, they were able to identify significant flooding events. Plugging this data into increasingly sophisticated climate models yielded a stunning result: New York will likely see “500-year flood heights” every 24 years. Reed said: “This is going from something you probably won’t see in your lifetime to something you may see several times.”

The defense

In 2007, Charleston formed a Green Committee to develop “a local action plan on climate change.” Community leaders met more than 140 times. More than 170 people participated. The Committee produced a 187-page report. Among its recommendations: the city should form a blue ribbon commission to create a comprehensive “sea rise adaptation plan.”

The committee said this adaptation plan should analyze how rising seas and more frequent downpours will affect the city’s infrastructure and economy. This plan should study the potential impact of saltwater intrusion into freshwater rivers and marshes, increases in pollen and mold, losses of homes and wildlife, and increases in disease-carrying insects. The committee urged that such a plan be implemented “with reasonable speed” — in two or three years.

None of this happened. City Council merely “received” the report. Eight years later, the city still has no comprehensive sea rise plan. The city had another chance in 2011 when it adopted its Century V Plan. It’s one of the city’s most important documents — a “statement of community values and goals,” according to the plan’s own description. City spokeswoman Barbara Vaughn said this plan “weaves within it many sustainability principles” from the Green Committee, “many of which the city of Charleston has embraced for decades.”

But a close reading shows that it lacks even a passing reference to rising sea levels. It has extensive analyses about population growth, density and appropriate designs for sidewalks and streets, but it has no discussion about how these streets and sidewalks will fare as higher sea levels breach that 7-foot tipping point. The plan mentions the city’s inadequate drainage system and its extensive and ongoing projects to reduce flooding. But those projects are grounded in plans in the early 1980s, before sea rise became an international conversation.

It wasn’t until late last year that Charleston Mayor Joe Riley finally convened a small staff committee to look at potential effects — hardly the blue ribbon commission the Green Committee envisioned. The report is expected to be completed by the end of the year, which some say is many years overdue. “We’re clearly lacking any type of comprehensive approach,” said Hamilton Davis, energy and climate director for the Coastal Conservation League.

Other communities in the area and the state as a whole share this scattershot response.

Charleston County has a 712-page“hazard mitigation plan” to identify the county’s most significant risks. It has sections on avian flu but no discussion of rising seas. A plan for Dorchester and Berkeley counties has only a brief mention. The state’s disaster plan also is lacking. A survey in late 2013 by the Columbia Center for Climate Change Law rated South Carolina’s hazard plan as giving “minimal mention of climate change related issues.”

The lack of urgency was apparent earlier this year during an international conference in North Charleston. More than 300 scientists and public officials from across the world gathered to discuss the impacts of sea rise and how cities might respond to them. There, officials from coastal cities spoke about work to protect their communities. Researchers revealed that rising seas could displace nearly 12 million on the coast during the next 85 years if seas rise 6 feet. As many as 350,000 South Carolinians could be affected. According to the conference’s organizers, not a single official from any Charleston-area local government attended.

Until the next one

City officials defend their responses to the threats posed by a warming planet. Laura Cabiness, the city’s director of public service, said that the city has raised several sections of roadway, such as Lockwood Boulevard and the intersection of Elizabeth and Calhoun streets. The city’s building code requires buildings to add 1 foot to the height from the ground for new construction in flood zones. “It’s difficult to plan ahead for 100 years,” she said. “It’s not something we’re used to doing.”

In an interview, Riley noted that the city has already built a multi-million dollar drainage and underground tunnel system in some parts of downtown to reduce flooding. A $50 million stormwater project for the Crosstown and surrounding areas is underway.

In the future, the city likely will fortify its edges, Riley continued. He pointed out that engineers are preparing plans to reconstruct the Lower Battery seawall at higher heights. He also anticipates “some form of abutment” along Lockwood Boulevard. A breakwater or sea wall likely will go in at some point along Morrison Drive on the Cooper River side of the peninsula. But, he acknowledged, last weekend’s record rainfall “certainly is a reminder” that more needs to be done.

After Hurricane Sandy in 2012 struck the New York area, leaders there quickly unveiled a $20 billion plan to defend the city against rising seas and storm surges. Some East Coast cities already have installed surge barriers or are planning to build them. In Washington, D.C., a sea wall protects Washington Harbour. Across the Potomac River in Alexandria officials are considering plans for a seawall to protect its downtown. In Portland, Maine, where tidal flooding threatens its old port area, the city is considering the installation of levees and surge barriers. Meantime, Miami, Baltimore and Norfolk, are seen by many as models of preparation for their sea level rise adaptation plans.

Closer to home, a few towns and developers are preparing for higher water and stronger storms. Developers of WestEdge, a large development project on the Ashley River, plan to build new roads 5 to 6 feet higher than existing levels, said Michael Maher, chief executive officer of the foundation guiding the project. As the project generates tax revenue, the city may be able to raise existing roads nearby, Maher said. “This kind of investment comes with significant dollar signs, but you can’t just keep kicking the problem down the road.”

In the absence of a pressing emergency, that’s easy to do, officials say. Ron Mitchum, executive director of the Berkeley-Charleston-Dorchester Council of Governments, says little regional planning for sea level rise has been of done by local governments.

They seem to be “just worried about their little areas,” Mitchum said. But last weekend’s flooding might “inspire some folks to a discussion of sea level rise,” he said.

Then again, with the floodwaters receding, so will the sense of urgency — until the next rain bomb or tidal surge makes our bathtub overflow again.