Climate Change and Hurricanes

Map showing the boundaries of Fort Pulaski National Monument including Cockspur Island and McQueens Island.

NPS/Seifert

As a barrier island situated along the mouth of the Savannah River, Cockspur Island is constantly in flux and has changed significantly over time due to natural and man-made factors. Human intervention has caused the greatest changes. Starting in 1829, a ditch and dike system was created to drain the island and place a barrier between the river and dry ground. This was necessary to prepare the ground before the fort could be built. Throughout the 1830s, a breakwater was built along the north shore to prevent erosion and preserve the island’s shoreline. The breakwater consisted of large rocks that ran parallel to the shore and occasionally jutted out in straight lines perpendicular to the shoreline. Despite this infrastructure, the island’s shorelines are ever-changing as storms and tides carve away and redeposit soil.

Cockspur Island is only a small part of the larger Fort Pulaski National Monument. Most of the National Monument consists of McQueens Island, which is to the south and west of Cockspur. While people have heavily adapted Cockspur Island over the centuries, McQueens Island is an eligible wilderness area, meaning it is primarily free from modern human manipulation and meets the characteristics of wilderness. In the next 30 years, both islands are expected to be more than 50% inundated due to sea level rise.

 

The above map shows Cockspur Island’s shoreline over time. The island grew substantially between 1874 and 1920 due to dredge spoil from the Savannah River being dumped on the marshy areas surrounding it. The south shore of the island faces less erosion than the north shore because the North Channel of the Savannah River is the main shipping channel. Therefore, the north shore of Cockspur Island sees much stronger waves.

NPS/Seifert

 

Hurricanes on Cockspur

Hurricanes have severely affected Cockspur Island throughout the centuries. The 1804 hurricane completely destroyed Fort Greene, an earthen and timber fort with a guardhouse for a 50-man garrison. Twenty-one people were in the fort when the storm hit. As the storm grew worse, they moved to the second floor, then onto the roof. At 1pm, the guardhouse collapsed. Survivors clung to sections of the roof and about half were swept out to sea. Seven people washed up on nearby Wilmington Island still clinging to the blockhouse wreckage, and one person survived in an island treetop. Seven enlisted men survived, and others were injured. One enlisted soldier died attempting to save an infant, who also perished. This storm would become the benchmark when building Fort Pulaski. Gen. Bernard, the fort’s architect, determined the parade ground should be 14 feet above low tide and six feet above the common tide, based on the 1804 hurricane storm surge levels.

In September 1854, another devastating hurricane hit the Lowcountry coast. The storm was massive, powerful, and slow-moving, which is a deadly combination in a hurricane. The storm, likely a Category 3, followed a similar track to the 1804 hurricane, even arriving on the anniversary, September 8. The hurricane did extensive damage to the fort and its support structures, including lifting the Carpenter’s Shop off its pilings and sweeping away the building and its contents. The hurricane also destroyed the South Wharf and caused extensive damage to the dikes and North Wharf.

On August 27, 1881, another severe hurricane dealt the final blow to the aging Workers’ Village and destroyed the lightkeeper’s house and the ordnance sergeant’s house, flooding the entire island. Inside the fort, there was five feet of water over the parade ground. The ditch and dike system, critical for draining and maintaining the island, was heavily damaged. Cockspur Island residents (lighthouse keepers, the ordnance sergeant, the quarantine officer, and their families) survived by hiding in the fort. An estimated 300 to 335 people died in the Savannah area, although these numbers are not very accurate and are likely higher.

 

Map showing projections of sea level rise for 2050 and 2100.

NPS/Seifert

 

Bone and iron utensil handle rusted onto a brick fragment. Picture was taken before any conservation work.

NPS/Seifert

Sea Level Rise: Cockspur’s Continuing Threat

For Fort Pulaski, sea level rise is a serious threat. The Fort Pulaski tide gauge has been collecting data continuously since 1935. This data shows an average increase of 0.12 inches per year from 1935 to 2013. The mean sea level has risen 1.04 feet in the past 100 years. Sea level rise results in the loss of land, including critical terrestrial and freshwater habitats and archeological sites. Sea level rise is causing a rising groundwater table, which means more “sunny day flooding” as the land becomes saturated. Saltwater intrusion into freshwater sources will contaminate drinking water. More flooding, especially saltwater flooding, will have unknown effects on artifacts buried in archeology sites. Archeologists think contact with saltwater will cause the artifacts to degrade faster and need more conservation treatment once excavated, much like artifacts from shipwrecks. These climate change effects not only harm the park’s natural and cultural resources but also lead to infrastructure damage and destruction. Without basics like our bridge, roads, and bathrooms, citizens can’t visit Fort Pulaski.

Park archeologists have already started to see the effects of increased saltwater flooding. Iron artifacts that are excavated show signs of severe corrosion and are often unable to be identified. They look like artifacts recovered from underwater archeology.

 

The Workers' Village site when it was flooded by Hurricane Irma.

NPS

Human-Caused Climate Change

The current climate crisis is caused by greenhouse gas emissions from vehicles, power plants, deforestation, and other human activities and will affect all aspects of the park including natural and cultural resources and the visitors’ experience. The potential for more frequent and more intense hurricanes is only one outcome of climate change. At Fort Pulaski, this means by mid-century, we will experience about 20 more summer days exceeding 95 degrees F and 10 to 15 fewer winter days with frost. It also means more extreme weather events such as droughts.

Other man-made factors affect the island as well. Large cargo ships motor up the Savannah River to the port causing waves to pound the island’s shores. To accommodate these ships, the river is intermittently dredged to maintain or deepen the depth. Dredging changes the average tides and the mean sea level of the river and encourages faster water flow, all of which contributes to erosion.

The photo to the right shows flooding on Cockspur Island due to Tropical Storm Irma in 2017. The wooden bridges that normally cross the moat were washed away due to the high water. Even more substantial flooding happened the previous year with Hurricane Matthew, which hit Cockspur Island as a Category 2. A Category 2 hurricane is not considered a major hurricane, but it still flooded all of Cockspur Island and forced Fort Pulaski National Monument to close for a month while repairs were made. As the planet continues to warm, hurricanes will likely grow more powerful.

 

It is hard to find artifacts when they are all smeared with mud. Here an archeologist found a very muddy bone button.

NPS/Seifert

Archeologists got really muddy hands while screening dirt along the north shore, near Battery Hambright. When archeologists encounter the water table, the soil becomes too watery to dig, forcing them to leave behind artifacts. Although it varies depending on the time of year and recent rainfall, the current water table on Cockspur Island is typically between two and three feet below the surface and rising with climate change, exacerbating the problem. In January of 2023, frequent (but not extraordinary) rain caused the water table to rise dramatically, turning the on-going archeology dig into a swimming pool. Archeologists were forced to wait for the water to drain until excavations could continue. Flooding continued to be a problem through the whole excavation season. Archeologists were forced to abandon units in the Laborers’ Quarters before reaching natural subsoil due to the damage done by constant unit flooding. The effects of climate change may seem small or distant, but they are very real, and soon they will not be hidden under the surface.

 

Groundwater flooded archeological units at the Workers' Village site, leaving archeologists with few options but to wait for the water to recede.

 

What are the Solutions?

Given the threats that Cockspur Island faces, the archeological excavations on the Workers’ Village serve not only to add to our current understanding of the island’s history and its people but also help to recover and preserve artifacts and history before it is too late. The effects of climate change could already be seen in the excavation units near Battery Hambright. Digging in these units stopped not because the number of artifacts in the soil decreased, but because the soil became too watery to dig and continued flooding destroyed wall profiles and threatened artifacts. To continue excavating here and the areas around it, archeologists would need a water pump to constantly remove water as they dig, which increases the time and cost of excavating thereby reducing the number of excavations they can do. The short-term solution? More archeology! By conducting as much archeology as is reasonable in the short term, we recover the data in the archeological sites before they are lost forever. Another solution is “beneficial dredge.” Just as dredging, or removing soil from the river’s bottom, can cause damage, it can also be a solution. The soil removed is pumped onto shorelines, creating wider beaches and a buffer between the river and marsh. Then when erosion occurs, it is this “sacrificial sand” that is carried away.

Our historic preservation colleagues also struggle with climate change. Recent work on the Cockspur Island Lighthouse hopes to both preserve the lighthouse itself and the fragile ground on which it sits. In 2012, the base of the lighthouse’s “island” was stabilized with rip rap (granite and concrete blocks). The lighthouse was originally built with its base eight feet above high tides. Today, the lighthouse has continually wet feet because of the rising tides. The 2012 stabilization was partially successful but needs on-going work. Infrastructure changes and “hardening” solutions like rip rap are tricky options because they are expensive, complicated, and can have other repercussions for the environment such as causing erosion elsewhere. The Cockspur Lighthouse, one of five remaining in Georgia, is in pretty good shape for what it’s been through. Relocating the lighthouse would be “technically infeasible” according to a recent study. For now, preservationists are being proactive, using routine monitoring and repairing as necessary with new materials that match the original ones. While researching and recreating historic recipes and materials to make the buildings more resilient, preservationists were pleasantly surprised to discover that the original materials are well suited to the salt and sand environment.

 

The Cockspur Island Lighthouse as seen during high tide. The lighthouse’s designers did not build its base in the water. Sea levels have simply risen over the past 100 years, and they will only continue to do so, putting this historic structure under further assault.

NPS

 

 

Next Section: Little Luxuries: Workers' Personal Items