Coastal erosion is accelerating—fueled by rising sea levels, intensifying storms, and disappearing natural buffers. Though these sites are primarily found along the Southeast and Gulf coasts, their lessons extend far beyond the shoreline. Massive shell mounds known as middens—large, layered deposits of shell, bone, and broken tools left by ancient Indigenous communities—are proving to be quiet climate heroes. Once dismissed as mere archaeological debris, these sites are now being reexamined for their ecological value. Built over generations, middens have endured for hundreds to thousands of years. And they’re still doing work.
Middens absorb wave energy, reduce erosion, and help anchor vegetation. They function as natural levees—buffering fragile islands from storm surge and tidal shifts without the ecological costs of modern seawalls. In doing so, they demonstrate that not all human impact is destructive. In some cases, our ancestors left behind tools we didn’t know we’d need.
What makes them effective is their material: calcium-rich shell fragments that compact over time and resist being washed away. Many middens are elevated, giving them a defensive height advantage. And because they’re porous, they don’t block water entirely—they slow it, soften it, and let ecosystems adjust rather than collapse.
These ancient structures also create habitat. Small mammals nest in them. Birds feed around their edges. Native plants take root in the mineral-rich soil. In Florida, the Carolina and Georgia coasts, and parts of the Gulf South, researchers have documented how middens support both biodiversity and soil stability—two pillars of climate resilience.
But as modern development pushes further into coastal zones, many of these mounds are under threat. Some are leveled for construction. Others erode simply because they’re not recognized as anything other than “old piles of shell.”
Preservation efforts are growing. In several southeastern states, archaeologists and ecologists have begun mapping remaining middens and lobbying for protective designations—not just as cultural heritage sites, but as functioning parts of the natural defense system. Projects like Louisiana’s Coastal Protection and Restoration Authority have begun incorporating similar natural strategies into their shoreline planning. In New York, the Billion Oyster Project is repurposing oyster shells to build reef systems that mirror some of the ecological benefits of ancient middens, demonstrating that traditional ecological knowledge can inform modern practices.
What’s emerging is a layered understanding of sustainability. These weren’t just dumping grounds—they were part of life systems. Food waste didn’t go to landfills; it became terrain. Discards were left in a way that served both function and culture. And they lasted.
The conversation around climate solutions often centers on innovation—new tech, new systems. But sometimes, the answer is older than we think. What if resilience is something we’ve already practiced—and forgotten? What if waste, handled intentionally, becomes legacy instead of liability?
In an era defined by rising tides and vanishing shorelines, the durability of these ancient structures offers more than nostalgia. It offers perspective. Human presence on the land doesn’t have to be extractive. And in some cases, the traces of who we were can still help protect who we are becoming.
Preserving middens isn’t just about honoring the past. It’s about learning from it—and building forward. As cities rethink how to survive sea-level rise, middens remind us that not all solutions are futuristic. Some are fossilized—and still working.