Built in a low lying area and mostly surrounded by marsh, St. Marys is in a precarious position as the sea grows.
“Sea level rise is perhaps the greatest climate challenge to the Georgia coast,” said Chuck Hopkinson, professor and program director of the Georgia Sea Grant College through the University of Georgia (UGA).
Hopkinson and other UGA employees were in St. Marys last week to talk with residents and city leaders about sea level rise at a symposium organized by the St. Marys EarthKeepers and held at Theatre by the Trax.
In the 20th century, oceans rose by about 1.7 millimeters annually or a foot total in 100 years, Hopkinson said. Studies show little change in global sea levels from 0 A.D. to 1900, according to the National Oceanic and Atmospheric Administration.
“Today’s flood will become tomorrow’s high tide as sea level rise will cause flooding to occur more frequently and last for longer durations of time,” NOAA states on an interactive tool that allows users to see the impacts of sea level rise and coastal flooding. The viewer is available at www.csc.noaa.gov/digitalcoast/tools/slrviewer.
As the world’s oceans warm causing the water to expand and land-based ice melts, sea level rises, according to NOAA. The seas may increase by 2 to 6 feet by 2100 depending on climate conditions, Hopkinson said.
In a Category 2 hurricane at the ocean’s current level, St. Marys is estimated to sustain $965 million worth of damage to 6,095 buildings, Jimmy Nolan explained at the symposium. Nolan is the local government project manager and works with geographic information systems through the Carl Vinson Institute of Government at UGA.
With 6 inches of sea level rise and a Category 2 hurricane, more of St. Marys floods, affecting 6,587 buildings at a cost of about $1 billion.
A rising sea also means less marsh along the coast.
“That marsh acts like a sponge when a wave hits it,” Nolan said. “It slows that wave down. If it’s gone, then the wave is going to come further inland.”
There are ways of adapting the natural coastline to protect communities, explained Jason Evans, an environmental sustainability analyst for the Carl Vinson Institute.
— Stand and defend using sea walls, levees, storm surge gates.
— Accommodate or buy time by replenishing sand on beaches and elevating buildings and roads in flood zones.
— Avoid or stay out of the way of rising water through setbacks and zoning designed to keep structures out of the extreme hazard areas by prohibiting building on land below a certain elevation.
— Retreat or get out of the way by using rolling easements, buyouts and not rebuilding in areas heavily affected by a weather event, such as a hurricane.
“City council and county commissions really need to debate and talk about what is really the appropriate thing for each community,” Evans said, noting finding the best remedy requires input.
NOAA offers a grant to help communities facilitate these conversations, Evans noted.
Kelly Spratt of the Georgia Sea Grant Program spoke briefly about the community rating system through the National Flood Insurance Program that offers discounted insurance rates to properties within a community that has exceeded federal standards for floodplain management and have met other criteria.