Coastal counties face population loss from sea level rise; Atlanta to gain residents
Coastal residents won’t be the only ones affected by rising seas this century, a new study out of the University of Georgia suggests.
“Sea level rise is currently framed as a coastal hazard, but the migratory effects could ripple far inland,” UGA demographer Matt Hauer wrote in a study published recently in Nature Climate Change.
“My results show the importance of accounting for future migrations associated with climate change in long-range planning processes for disaster management, transportation infrastructure, land-use decisions and so on.”
The study looked at likely migration to and from every U.S. county and metropolitan area in the face of a sea level rise scenario of 1.8 meters, or nearly six feet, by the year 2100. That’s higher than the current rate of about a foot a century, but less than the latest worst-case scenario of 2.5 meters (just over eight feet) predicted in a January technical report from the National Oceanic and Atmospheric Administration.
Hauer examined two scenarios. First, he looked at what would happen with no adaptation to rising seas such as sea walls and other fortifications. Then he looked at how such adaptations would mitigate migration.
To model where the previously estimated 13.1 million sea level rise refugees nationwide were likely to go by the turn of the next century, Hauer looked at current migration patterns seen in Internal Revenue Service data, which tracks county-to-county migration of taxpayers when they file a return from a different county than in the previous year.
“The projected net gains or losses are due to just the migration,” Hauer wrote in an email. “So if five people move into a state and two people move out, the net change is plus three.”
The Atlanta metro area stands to gain a quarter-million residents or more in both scenarios, giving it the third-highest net gain in the country behind the Austin and Orlando areas.
The Savannah metro area, by contrast, stands to see a net loss of nearly 60,000 residents, putting it in 20th place nationwide for largest net loss among statistical areas. Some of those residents would be moving within the statistical area, a look at the county numbers shows.
Chatham County is expected to lose nearly 75,000 people without any adaptation (or 61,000 with adaptation), but Effingham gains more than 12,000 in either scenario.
The Hilton Head-Bluffton-Beaufort statistical area faces similar losses to the Savannah area with a net out-migration projected at a high of nearly 65,000.
Five of Georgia’s six coastal counties are likely to lose population from sea level rise by 2100. Liberty is the only coastal county projected to see a net gain. Interior counties will pick up some of those transplants as the state reshapes itself in response to climate change.
Savannah-based planning consultant Todd Holloway has also been considering the impacts of sea level rise on the cultural landscape of the Georgia and South Carolina coasts — but in terms of culture rather than population numbers. At a recent conference on urban planning at Savannah State University, Holloway zeroed in on its effects on one group in particular, the Gullah-Geechee community, whose way of life is closely linked to the marshes and salt water.
“They live in these areas now that are going to become constantly flooded by storm surge and where are they going to move to?” said Holloway, founding principal, HollowayEPI/sc and EVOKE Savannah in a post-conference interview.
“They’re not going to move immediately a half a mile out of harm’s way because the richest people live a half a mile out of harm’s way. So the places where they’re going to be displaced to are going to be quite a distance from where they traditionally used to live.”
Hauer doesn’t predict who will move but does note that questions of shifting populations are important for both coastal and inland communities.
“Local officials in landlocked communities can use these results to plan for potential infrastructure required to accommodate an influx of coastal migrants and could shift the conceptualization of sea level rise from a coastal issue to a more ubiquitous issue,” he wrote.