New geological evidence uncovers the climatic chain reaction behind an empire’s long decline.

In a fascinating turn of historical and scientific discovery, researchers have uncovered compelling geological evidence pointing to a little-known climatic phenomenon—the Late Antique Little Ice Age (LALIA)—as a major force that contributed to the gradual collapse of the Byzantine Empire.

Though often overshadowed by military defeats and political turmoil, this prolonged cold period, which began around 540 AD, may have had a much more significant impact on the empire’s fate than previously believed.

A Cold Snap with Catastrophic Consequences

According to Professor Thomas Gernon of the University of Southampton, LALIA was triggered by a series of three massive volcanic eruptions. These eruptions launched vast quantities of ash into the atmosphere, blocking sunlight and sending temperatures plunging across Europe. This cold spell lasted for 200 to 300 years and coincided with major geopolitical upheavals, including widespread population migrations.

During LALIA, average temperatures in Europe dropped by 1 to 2 degrees Celsius. While that might sound minor, the consequences were anything but—crop failures, livestock die-offs, skyrocketing food prices, and ultimately, famine and rampant disease.

The Justinian Plague and Political Instability

LALIA also overlapped with one of history’s deadliest pandemics—the Plague of Justinian, which struck in 541 AD and killed an estimated 30 to 50 million people worldwide, roughly half the global population at the time.

This health crisis came during a period when the Byzantine Empire was already strained by constant warfare from Emperor Justinian’s expansionist campaigns and deep internal religious conflicts.

“These events coincided with a volatile period in the Eastern Empire,” explains Professor Gernon. “The empire was engaged in near-constant wars, territorial expansion under Justinian, and religious strife.”

Gernon adds that LALIA severely weakened the empire’s ability to recover from these overlapping crises, compounding the challenges it faced and accelerating its long-term decline.

“It seems likely that LALIA tipped the balance at a time when the Byzantine Empire was already stretched to its limits,” he notes.

The Geological Evidence Behind the Theory

The research team identified unusual rock formations on an elevated marine terrace in northwestern Iceland. To trace their origins, scientists pulverized the rocks and extracted hundreds of tiny zircon crystals, which were then analyzed for their chemical composition and age.

“Zircons act like time capsules, preserving chemical information and recording the moment they crystallized,” explains Dr. Christopher Spencer, lead author of the study and Associate Professor of Tectonochemistry at Queen’s University.

Their analysis revealed that the rocks originated in Greenland and were transported to Iceland by icebergs during the LALIA period.

These findings, according to Gernon, highlight two key insights:

The Greenland ice sheet experienced significant fluctuations during that time.
The climate was so cold that glaciers extended far enough south to alter Iceland’s geology.

A Slow-Burning Collapse

While the final fall of Constantinople didn’t occur until centuries later in 1453, the new data strengthens the case that LALIA played a pivotal role in weakening the empire over the long haul.

“To be clear,” Gernon emphasizes, “the Byzantine Empire was already in decline when LALIA began. But our findings suggest that climate change was more severe than we thought and likely acted as a key driver of societal transformation—not just one factor among many.”

This research not only reshapes our understanding of Byzantium’s downfall but also serves as a powerful reminder: climate events, often overlooked in historical narratives, can steer the fate of civilizations just as much as wars, politics, or pandemics.