New Study Reveals Iceberg-Driven Climate Crisis that May Have Triggered the Fall of Rome

Coastal Greenland, where the rocks analysed in the study were pinpointed to. Credit: Professor Ross Mitchell, The Institute of Geology and Geophysics, Chinese Academy of Sciences

(IN BRIEF) A team of scientists from the University of Southampton, in partnership with researchers from Queen’s University in Canada and the Chinese Academy of Sciences in Beijing, has discovered new evidence detailing the intensity of a 6th century climate crisis known as the Late Antique Little Ice Age. The study analyzed unusual rock formations found in a raised beach terrace on Iceland’s west coast, concluding that these rocks were deposited by icebergs during a brief ice age that began around 540 AD and lasted between 200 and 300 years. This climatic downturn, potentially initiated by massive volcanic eruptions, may have exacerbated the decline of the Roman Empire, triggering mass migrations that reshaped Europe. By extracting and analyzing tiny zircon crystals from the rock samples—serving as time capsules of geological history—the team was able to trace their origins to multiple regions in Greenland, thereby confirming their glacial provenance. The deposition of these rocks is linked to the Bond 1 event in the 7th century, when significant ice-rafting occurred amid the post-glacial rebound. The research underscores the profound interconnectivity of the climate system and its potential role in historical societal collapses.

(PRESS RELEASE) SOUTHAMPTON, 9-Apr-2025 — /EuropaWire/ — Scientists at the University of Southampton have uncovered compelling new data that illuminates the scale and severity of the Late Antique Little Ice Age—a climate crisis during the 6th century that coincided with the collapse of the Roman Empire. In a collaborative investigation with experts from Queen’s University in Canada and the Chinese Academy of Sciences in Beijing, the research team examined atypical rock samples from a raised beach terrace along Iceland’s west coast. These rocks, it was revealed, had been transported by icebergs during a brief ice age that is believed to have begun around 540 AD and lasted between 200 and 300 years.

Collection of ancient rocks analysed in the study, which have been traced to geological provinces of Greenland. Credit: Dr Christopher Spencer, Queen’s University, Canada

For years, historians have speculated about the role that abrupt climatic cooling might have played in hastening the decline of the Roman Empire. The latest evidence strengthens this hypothesis, suggesting that a transient but intense cooling event could have been the final trigger in an already faltering empire, spurring large-scale migrations that reshaped Europe during that period.

Professor Tom Gernon, an Earth Science specialist at the University of Southampton and a co-author of the study, remarked, “When we consider the decline of the Roman Empire, this climate shift may have very well been the straw that broke the camel’s back.” The researchers propose that this brief ice age was instigated by volcanic ash from three massive eruptions, which significantly reduced sunlight and subsequently lowered global temperatures.

Tiny zircon crystals separated out from ancient rocks from Greenland. The lines (called zoning) record the growth of the crystal in magmas over time, much like tree rings. Credit: Dr Christopher Spencer, Queen’s University, Canada

The study, published in the journal Geology, delves into these dynamics by analyzing rock samples using a range of sophisticated techniques. Dr. Christopher Spencer, Associate Professor at Queen’s University and the study’s lead author, explained that the anomalous nature of the rocks—uncharacteristic of today’s Icelandic geology—prompted the investigation. By crushing the rocks to extract minute zircon crystals—tiny time capsules that record their formation age and chemical signature—the team was able to match these crystals to specific regions in Greenland, spanning nearly three billion years of Earth’s history.

Professor Ross Mitchell from the Institute of Geology and Geophysics at IGGCAS added that the presence of non-basaltic rocks in Iceland initially hinted at their arrival via iceberg. The discovery of cobbles—fist-sized, rounded rocks—further corroborated the glacial transport hypothesis, as these rocks originated from diverse geological provinces across Greenland. According to Professor Gernon, the diverse nature of the rock assemblage is clear evidence of glacier activity, where erosion produces a chaotic mix of debris that icebergs subsequently transport.

The team concluded that the deposition of these ice-rafted rocks likely occurred during the 7th century, coinciding with the Bond 1 event—a known period of significant ice-rafting that occurred as the land rebounded following the melting of the last ice sheets. Dr. Spencer summarized the broader implications, stating, “This is a striking demonstration of how interconnected our climate system is; as glaciers advance and icebergs calve, the shifting ocean currents and altered landscapes are a testament to the far-reaching impacts of rapid cooling.”

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SOURCE: University of Southampton