Georgia coastal wetlands need room to move, report says

A new study draws attention to the need to conserve undeveloped land in coastal areas to accommodate wetlands as sea levels rise.

On Tybee Island near Savannah, higher tides and sunny day flooding have become regular occurrences.

The city has built up sand dunes and beaches, and now requires new construction to be raised above flood level. Tybee officials have also secured funding to raise at least 22 homes and the city is planning for more.

“It doesn’t take an ideological, political stance to look at data and see we’re getting more frequent high tide events on Tybee,” City Manager Shawn Gillen said.

Georgia’s coastal wetlands are under threat from rising seas, and how the state and local communities respond could spell the difference between a net gain or a net loss of these vital ecosystems, a new study says.

U.S. coastal wetlands could either increase by 25% or decrease by 97% over the next century, depending on a number of factors, including how quickly humans can reduce carbon emissions and how much coastal land is set aside for conservation, researchers found. The report calculated that these changes could result in an annual gain of $222 billion to the U.S. economy or an annual loss of as much as $732 billion.

The study, conducted by Climate Central, a research nonprofit, and published in Environmental Research Communications, projects best- and worst-case scenarios for coastal wetlands across the contiguous United States, including Georgia.

“The first worst-case scenario is much worse than the best best-case scenario,” said Siddharth Narayan, an assistant professor of integrated coastal programs at East Carolina University, who reviewed but was not involved in the study.

“If we want to increase wetland coverage, that’s going to be harder to do” than taking no action and losing most of the country’s coastal wetlands, he added.

Credit: Stephen B. Morton

Credit: Stephen B. Morton

Georgia’s coast is among the least developed in the nation. The state’s barrier islands and inland waterways include a vast network of marshes home to a diverse ecosystem of plants and wildlife. Those island buffers also protect inland areas from hurricanes and flooding.

But climate change is a threat.

“Sea level rise is a fact,” said Jennifer Kline, who oversees coastal hazards and disaster resiliency for the state Department of Natural Resources. “We have scientific evidence here on Georgia’s coast that it has been occurring and is steadily increasing.”

Although Georgia fared slightly better in the Climate Central report’s model than some other Southern coastal states — notably Florida, Louisiana and North Carolina — it remains vulnerable to significant loss of wetlands.

Moving wetlands

As sea levels rise, coastal wetlands migrate inland. But wetlands need undeveloped land to move to, and such property is at a premium along much of the U.S. coastline. Where development limits migration, wetlands can disappear.

The importance of wetlands as habitats and buffers for human settlement against extreme weather and flooding is only growing as temperatures rise and storms become more destructive.

“One thing that we can do to offset some of the impacts [of sea level rise] is to keep nature natural,” Kline said. “That way, it allows for further migration of that salt marsh.”

But keeping nature natural often runs up against competing interests along the coast, where private property abuts public lands. Development in these areas is controlled by multiple layers of government whose priorities are not always aligned.

For example, federal agencies like FEMA and the Army Corps of Engineers that approve wetland infrastructure are bound by cost-benefit formulas critics say are out of date and do not take into account the broader economics of, say, tourism in coastal areas. These formulas tend to be unfavorable to green infrastructure — things like adding sand to beaches or creating open green spaces that are designed to flood.

At a state level, Georgia places a high premium on private property rights, which in turn limits what local counties and cities can require of developers, businesses and homeowners on the coast.

“The fundamental issue is the right of the individual property owner versus the obligation of a municipality to protect its citizenry,” said Alan Robertson, a principal at AWR Strategic Consulting who has been hired as a resiliency project manager for Tybee Island.

Tybee describes its approach as “defend, adapt and retreat.” But there are limits.

“We need to take a serious look at not just grants to lift homes but grants to acquire the homes and tear them down and create green space,” Gillen, the city manager, said. “... But that takes time, especially here in Tybee because every square inch is built on and the land is extraordinarily valuable.”

Some other states have passed laws enshrining protections into state law. In Texas, for example, the Open Beaches Act established as public property all land between the low tide line and the vegetation line, and outlawed any hard infrastructure that can inhibit natural erosion.

Other localities, like Norfolk, Virginia, have developed incentive programs for developers and property owners to place vulnerable parcels in conservation.

Credit: Curtis Compton

Credit: Curtis Compton

In Georgia, the Coastal Marshlands Protection Act places all salt marshes under state control for conservation. The boundaries of salt marshes are determined by the presence of 14 native marsh plants named in the law, as well as tidal elevations — both of which move with the changing coast.

Still, Kline said overdevelopment along Georgia’s coast is a concern.

“I don’t know that there’s any way to stop that with private property rights,” she said. “That’s why we really have encouraged our local governments to be forthcoming with developers and homeowners on mitigation and adaptation so that we are offsetting some of the impacts.”


A note of disclosure

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