Miami residents dodging sea-water spewing manhole covers take note: You’re not the first Floridians to deal with climate change.
That honor belongs to the state’s earliest residents, some of whom faced the problem 2,000 years ago and quickly learned how to adapt, a new University of Florida study shows.
The remains of Florida’s first climate-change resettlements offer important lessons from the past, just as rising seas again threaten the peninsula’s coastal populations, says a University of Florida scientist.
Targeting areas affected by rising seas after the last ice age, geoarchaeologist Paulette McFadden reconstructed how the changing coastline affected the history of several ancient settlements along the state’s Gulf Coast.
The coastal-dwelling ancestors of the Timucua and Apalachee drew from centuries of historical knowledge to develop specific strategies for resettlement after rising seas swallowed their original settlements, said McFadden, lead author of a study appearing online today in the journal Geoarchaeology and postdoctoral researcher of Florida archaeology at the Florida Museum of Natural History.
This early chapter of Florida’s history could improve our understanding of how different coastal environments will be affected by sea level rise. By utilizing information gleaned from archaeological research that sheds light on the historical knowledge of ancient Floridians, we could create customized sea level rise reaction plans for diverse coastal environments, and mitigate social and economic impacts of sea level rise in the future, McFadden said.
“As the shoreline moved inward, these early people were forced to make decisions about how to live in this new world that was being created,” she said. “They had ideas for surviving in coastal environments integrated into their very culture. Certainly when you put meaning on a place, it’s hard to lose it, but they had adaptive strategies and knew what needed to be done. It wasn’t as traumatic as you might think. It was more likely a strategically planned movement when the time came.”
McFadden said she “read the dirt” by radiocarbon dating sediment cores and soil collected offshore and associated with environmental change, as well as charcoal recovered from former villages, to reconstruct centuries of changing sea level and movement of villages.
At Horseshoe Cove near Cedar Key, McFadden and colleagues uncovered an ancient resettlement dubbed “Garden Patch,” which was created around A.D. 25 after rising seas flooded an older settlement. The inhabitants built the Garden Patch village in an area that bordered marsh, back away from the shoreline, along a tidal creek that gave them easy access to marine resources, but still far enough away that they were protected from rising seas and storms, McFadden said.
While utilizing the marshes as protection works great on the Gulf, that’s not the case on Florida’s Atlantic Coast where there are fewer marshes to buffer the energy of waves, McFadden said.
“The east coast will erode away much faster, so we should plan for that,” she said. “The take-away from this study is that we need different strategies for different coastal environments around the world. A homogenous reaction isn’t the right answer. Studies like this one can help us understand which types of coasts we need to focus on as far as sustainability and what sorts of things we can do to prevent coastline degradation.”
Some archaeologists have suggested that some of the oyster bars along the Gulf Coast are old settlements that became inundated, McFadden said. Archaeologists have also discovered an archaic site more than 8,000 years old submerged beneath 20 feet of water off the Gulf Coast. McFadden found evidence that, like the inhabitants of modern cities like Miami and New Orleans, early Native Americans made efforts to stay in places for as long as possible and even returned to settlements after they had become islands.
Tactics for adapting settlements to rising seas included building up piles of seashells to elevate residences and abandoning large villages for more easily sustainable small ones. Even Garden Patch was abandoned for a century after a pulse in sea level rise occurred around A.D. 660, which may have resulted in oyster reef extinction and less food for the villagers.
“There were times when sea level was rising fairly fast after the last ice age, and within one’s lifetime they may have seen the creation and movement of villages,” McFadden said. “These pulses in sea level are comparable to the accelerated sea level rise that we’re seeing today.”
At Garden Patch, the former inhabitants returned after sea level rise moderated and resources returned, said Neill Wallis, assistant curator of Florida archaeology at the Florida Museum.
“It appears they only went back to areas previously occupied,” Wallis said. “So they were not targeting the environment. These places had meaning drawing people back to them. Some of the settlements are even very vulnerable to storms and erosion. But they utilized these places, even though they’re not necessarily the wisest or easiest places to live.”
• Learn more about the Florida Archaeology at the Florida Museum.