Powered by Google

Search form

Increasing Sea Levels

May 19, 2014

When Jennifer Priest bought her house in Norfolk, Va., 15 years ago, she never thought she’d become a poster child for coastal flooding.

But her modest rambler, in an attractive neighborhood not far from the southern end of Chesapeake Bay, has been inundated three times in the past nine years due to storms, land subsidence and a rising sea. Fortunately, she has federal flood insurance which has covered at least part of her losses.

“I had no inkling when we purchased this house in 1999,” said Priest, the mother of three and college fundraiser by profession. “It was built in 1951 and received two inches of water during Hurricane Hazel (in 1954). That was it, but things have gotten wetter since then.”

Priest isn’t alone. All up and down the East Coast — as well as along the Gulf of Mexico — rising sea levels and sinking land are causing major troubles for homeowners, cities, businesses, military bases and even wildlife refuges.

Most climate scientists say the situation is only going to get worse, with predictions of ocean levels rising up to a meter over this century.

A Great Threat

Ben Horton, a professor at the Rutgers University Institute of Marine and Coastal Sciences, called the problem “a great threat because the United States has so much property and infrastructure and population along the Atlantic coast. There are many examples of the effects of climate change, but the biggest financial impact is from rising sea levels, which have been increasing since we came out of the industrial revolution.”

While 2012’s Hurricane Sandy caused a huge amount of destruction to New York and New Jersey with its 13-foot tidal surge, Horton said increases in the base level of the ocean exacerbated the problems.

“You can never say one hurricane is caused by climate change, but you have to ask, how often will storms like Sandy occur in the future?” he asked. “Was it a once in a century event or will it be once in a decade? 

“The impacts will be profound. If you look at what happened in 2012 and compare it to a hurricane with a similar surge in 1821, it flooded about 100,000 square kilometers (37,000 square miles) more because the sea had risen 50 centimeters (19 inches.)”

Even without epic storms, Horton said climate-related sea level increases can cause massive problems for coastal areas because it increases frequent flooding, which causes erosion, contaminates drinking water supplies and aquifers, damages farmland and decreases habitat for fisheries, wildlife and plants.

“No one likes to hear it, but in the 21st Century, it’s clear some people will have to abandon their homes,” he said. “Low-lying coastal islands will be lost forever. We have committed to sea level increases due to the burning of fossil fuels. So what we are faced with now is how high do we want those levels to go and are we willing to mitigate and slow the high rates of sea level rise so we can adapt.”

Horton, a native of England who came to the United States a decade ago and “fell in love with the Carolinas,” said each coastal area has its own problems.

“The cutting edge of science now seeks to understand the regional impacts of sea level increases. If we take the U.S. coast line as a whole, the area that is most susceptible to sea level rise is the Mississippi Delta in part because of land subsidence. If you look at the instrumental records of tide gauges, you’ll see rates of around 10 mm (.4 of an inch) a year.”

He said Florida is also very susceptible because it is coastal plane on a limestone bedrock base “that acts a bit like a sponge.

“So not only do we get troubles along the coastline, but we have problems on the interior. The sea level rise will have a big influence on its aquifer, and you’ll also have the potential of huge ecological changes to the Everglades.

“Worse, most of Florida’s population lives on the coast,” he said. “Something like 80 percent of the state’s economy is in these coastal counties. In 2010, the value of that built environment and infrastructure was some $2 trillion. The rates of sea level rise in Florida are not as rapid as elsewhere, around 2 millimeters (less than .1 of an inch) a year, but it’s happening.”

Further up the Atlantic coast, Horton said Virginia is the “hotspot” because of land subsidence related to geological processing cause by a long-disappeared ice shield. That phenomenon, he noted, has nothing to do with global warming. But it will continue for thousands of years.

In the short term, he said cities are raising roads, fortifying sewer and water systems, building sea walls and reinforcing dikes. Some shoreline communities are putting in dunes to protect homes.

But to slow sea level increases — which are caused primarily by melting glaciers and the expansion of warming oceans — he said the rate of global temperature increase must be slowed. The only way to do that is to reduce the output of so-called greenhouse gasses, caused primarily by carbon dioxide emissions from industry, automobiles and other human activities, Horton said.

“You can adapt to regional threats with both hard and soft engineering approaches, he said. And while things like sea walls and tidal barrages are very effective, he said they are also “very, very expensive.”

“And you can re-nourish the beaches,” he said. But when sea levels rise, the coast retreats. “To balance that, you put sediment on beach. But that is only temporary. You keep on having to replenish it.”

“Or you just retreat. Only the most valuable areas will have the economic wherewithal to be protected this way with hard engineering solutions. What New York City is doing is a classic example.”

But Horton said not all shorelines will be saved. Some will be left to the forces of nature.

Fortifying Assets

In Delaware, the state is mulling options to fortify seven threatened beach communities from east of Dover to north of Lewes. Some taxpayers are questioning these plans, which could cost hundreds of millions over the next 30 years.

Nearly $70 million would be needed to pump enough sand onto shorelines to protect the eroding beaches through the next decade, according to the Delaware Department of Natural Resources and Environmental Control. Over the next two decades, an attempt to stage an orderly retreat while still saving some houses and beachfront would cost another $62 million or more, according to state estimates. If Delaware were to buy out the 451 most vulnerable owners along the seven shores, it would cost upwards of $154 million over the next three decades.

And in New Castle, just south of Wilmington, Del., the community spent millions of dollars recently to fortify dikes built more than two centuries ago by Dutch and Swedish settlers to keep the ocean at bay.

“If you remove emotion from it, it’s a simple cost-benefit analysis,” Horton said. “That’s where science needs to inform. You need to have best quality information telling you what the regional scenario will be. Then you can estimate what infrastructure will be affected and what areas will be flooded. You can then make decisions, because there are very different risks associated with the effects of sea level rise on a home and an international airport or a nuclear power plant.”

Though communities are making plans to protect their assets, Horton said many politicians are reluctant to deal with the long-term problem.

Politicians and Climate Change

“While 98 percent of scientists believe climate change is real, politicians continue to question if global warming is real,” he said. “Until they aren’t influenced so much by special interest groups, and we have appropriate education so that the general public understands, change on a broad level won’t happen. But younger people seem to be accepting that this is real, so there is great hope that the next generation will deal with this, perhaps through grass roots efforts.

“That’s my hope. But the United States can’t do it alone. While the United States and the developed world are responsible for most of the carbon emissions and sea level rise through the 20th century, the 21st Century will be controlled by other emitters like China and India. They are now producing more carbon than the United States, so there will have to be international cooperation.”

In Norfolk, emergency response director Jim Redick said that while his city dodged the brunt of Sandy — which would have been “catastrophic” — coastal flooding is considered its biggest threat.

“The ocean is rising,” said Redick, whose community got a Rockefeller Foundation grant to help with its planning. “I can see it on our streets with simple nuisance flooding on lunar high tides. We are looking at infrastructure projects to get funds to raise roads and considering flood walls and other gray and green
strategies.

“At the same time, my shop is trying to get FEMA grants to elevate properties with the understanding that even though the home may be elevated, it could be an island if the streets are underwater.”

Redick, who is a member of Virginia’s Secure Commonwealth Commission, said the city is considering building a sea wall, but the price tag is more than $1 billion. “And that is certainly more than one locality can afford. So we are trying to come up with a state strategy so every community isn’t fighting on its own for federal dollars.”

Redick said the commission has not argued about the cause of sea level rise. “It’s not become a controversial political issue. We know it’s occurring. For me, it’s kind of like putting out a fire first. Then we can find out what’s the cause. Which is why I think it’s a good thing the governor is re-establishing his commission on climate change. Someone needs to focus on the ‘why,’ too.”

Redick said rising insurance rates for homes near the water may force some people to move. He also said he believes if the city has to retreat from some areas, homeowners and businesses should be compensated for their losses.

William Lucks, who served on Delaware’s Sea Level Rise Advisory Committee, agreed and said “as a member of the Delaware Association of REALTORS®, working to protect private property rights, yes I do agree with the compensation.”

Meanwhile, Jennifer Priest is content to hunker down and enjoy her Norfolk home for as long as she can. 

“I don’t know how easy it would be to sell this place as prone as it is to flooding now,” she said with a wry laugh. “Besides, I like where I live. So I’ll just make sure my insurance agent’s email and cell number are up-to-date. I’ve dealt with him the last two times. Fortunately, he’s a lovely man.”