Image: Congratulations to Davis Huber, who received an Honorable Mention for his talk on Georgia’s barrier islands and climate change at the annual AAAS meeting in Boston this year! 25 Years of Climate Change Threaten to Shrink Georgia’s Barrier Islands and Marshes AAAS Annual Meeting 2025 Background: Barrier islands in the southeastern United States are diverse habitats, efficient carbon sinks, sources of industry and economy, and are the primary line of defense against winds and waves from storms. These important islands are threatened by sea level rise (SLR) and slow, powerful hurricanes created by warming climates. While many studies detail the effect of SLR and hurricane damage at localized scales, rarely are island-scale changes, or interactions with nearby islands, addressed. Several of Georgia’s barrier islands are in proximity to each other, and in those cases, they behave as a single unified system, rather than as individual, unrelated islands. The objective of this study is to document the historical interactions within the Sapelo Island system (containing Sapelo, Blackbeard, and Cabretta Island) in response to SLR and hurricanes by measuring changes in beach position, salt marsh area, and island size. Methods: Satellite imagery (Google Earth Pro, GEP) was used to measure beach position, marsh area, and island size for the three islands from 1988 to 2023. GEP’s measure and polygon tools were used to extract distance and area measurements. Changes in beach position were recorded at the northernmost and southernmost beaches of the islands, where the most deposition and erosion occur. Measurements for island size were based on the vegetated area (maritime forest, dunes) of each island to avoid tidal bias. Results: Over 25 years, Sapelo and Blackbeard’s beaches had net southward growth at an average rate of 2.5 m and 3.9 m per year respectively. Cabretta’s beach shrunk at an average rate of 26.1 m per year—mostly in response to the southward migration of the tidal inlet between Cabretta and Blackbeard—resulting in the loss of ~250,000 m² of salt marsh. The rates of deposition and erosion on all three islands accelerated each year, culminating in 308,551 m² of combined area loss by 2023. Conclusions: Accelerating erosion and deposition rates indicate that longer, more powerful storms and SLR cause sediment to move faster, which can result in island shrinkage. Under present conditions, Cabretta island will be completely eroded in ~83 years, resulting in the loss of an additional ~1,300,000 m² of ecologically and economically valuable salt marsh. While Blackbeard and Sapelo currently have net annual growth, the absence of Cabretta from the Sapelo Island system may make these islands more vulnerable to erosion from storms. For this reason, assessing barrier islands as a unit is essential to understand their responses to climate change. Type of News/Audience: Department News Tags: Climate Change Georgia Barrier Islands and Marshes
