In the muddy lowlands of Georgia's coastal swamps, the remains of ancient bald cypress trees hold vital clues to centuries of past climate shifts etched into their rings.

A study led by Florida Atlantic University reveals how the lives — and deaths — of these trees chronicle sweeping environmental changes dating back more than 2,500 years. The findings offer a stark reminder of how climate shifts, even from centuries ago, can leave long-lasting marks on the natural world.

"These ancient giants not only inspire awe but also serve as natural archives, helping scientists understand how trees have weathered past climate events — and how they might fare in the face of modern climate change," said Katharine G. Napora, Ph.D., senior author of the study and assistant professor in the Department of Anthropology in the Dorothy F. Schmidt College of Arts and Letters.

Working alongside researchers from Lynn University, the University of Georgia, and the Georgia Museum of Natural History, Napora and her team analyzed 95 preserved bald cypress trees unearthed from the Altamaha River area. Using radiocarbon dating and tree-ring analysis, they reconstructed nearly three millennia of growth patterns.

Before the year 500 A.D., these trees routinely lived for nearly 500 years. But then, something changed. Around the time of a global climate downturn known as the Vandal Minimum — linked to volcanic eruptions and possibly even a comet impact — the trees' lifespans began to shrink. Post-500 A.D., the average bald cypress lived just 186 years, growing more quickly but dying sooner.

"This shift wasn't a brief disruption. Even centuries later, the trees never regained their former longevity. In fact, their lifespans continued to decline over time," Napora said.

"The last of the long-lived trees found in the deposit died during another major climatic event, the Little Ice Age. Our findings underscore how long-lasting the localized effects of major climate shifts can be, especially for coastal forests that are already vulnerable to wind damage, saltwater intrusion and rising seas."

The study found no evidence of fire, logging or other human activity causing the decline — just nature, changing course. Drier conditions may have triggered insect outbreaks. More unstable flooding and rising salinity likely made the swampy environment even harder to survive. And yet, hope endures. Today, bald cypress trees more than 1,000 years old still stand in isolated groves. Their resilience offers lessons for the present.

"The rings of the bald cypress are like nature's journal entries, written year by year and season by season, showing how even slow changes can shape the course of life," Napora said. "In their quiet persistence, these trees offer both a warning and a lesson: that the world is more interconnected than we often realize, and that the story of the Earth isn't only told through written history — it's etched into wood, embedded in landscapes and carried forward by living organisms."