Mini Ice Age may have fuelled collapse of Roman Empire

Telegraph

08-04-2025

A 'Little Ice Age' in the sixth century was so intense it may have been the 'primary driver' in the fall of the Roman Empire, scientists believe.
Between 536AD and 547AD, three massive volcanic eruptions blocked out the Sun and ushered in a rapid period of cooling which saw average temperatures fall by several degrees.
Researchers at the University of Southampton have found that the mini Ice Age was so intense that it moved rocks from Greenland to Iceland.
The scientists found smooth rounded rocks known as 'cobbles' on the beaches of Iceland's west coast which must have been carried on icebergs from Greenland.
It suggests that the cooling event sparked changes even more widespread and severe than previously thought, causing major climate upheavals in the northern hemisphere that probably played a pivotal role in the collapse of the Roman Empire.
'When it comes to the fall of the Roman Empire, this climate shift may have been the straw that broke the camel's back,' said Prof Tom Gernon, co-author of the new research and an earth science professor at the University of Southampton.
'The climate was particularly cold at the time – cold enough for icebergs to reach and noticeably impact the geology in Iceland,' Prof Gernon added.
'The Roman Empire was likely already in decline when the Little Ice Age began. However, our findings support the idea that climate change in the northern hemisphere was more severe than previously thought.
'Indeed, it may have been a primary driver of major societal change, rather than just one of several contributing factors.'
The period of cooling, dubbed the Late Antique Little Ice Age, lasted around 200 to 300 years.
It is known to have coincided with a period of widespread social unrest across Europe and Asia, which saw the Roman empire giving way to the Byzantine era.
By that time, the Roman empire had shrunk to the Mediterranean and continued to decline because crop failures induced by the cold, famine and plague.
As well as the Romans, the huge climate shift also saw Chinese dynasties falling as well as the Eastern Turkic empire.
The new findings, published in the journal Geology, show that the climate disruption reached far into the North Atlantic Ocean.
Experts had known that the beach rocks on Iceland's west coast did not belong there but were unsure where they had come from until they studied their age and composition.
The team found that the rocks came from Greenland by analysing the age and composition of tiny zircon crystals. Zircon is one of the primary minerals used to determine the age of rocks.
'We knew these rocks seemed somewhat out of place because the rock types are unlike anything found in Iceland today, but we didn't know where they came from,' said Dr Christopher Spencer, associate professor at Queen's University in Kingston, Ontario, and lead author of the research.
'Zircons are essentially time capsules that preserve vital information including when they crystallised as well as their compositional characteristics.
'The combination of age and chemical composition allows us to fingerprint currently exposed regions of the Earth's surface, much like is done in forensics.'
The team discovered that the age of the fragments spanned nearly 3 billion years, and were able to trace the rocks back to specific regions of Greenland.
'This is the first direct evidence of icebergs carrying large Greenlandic cobbles to Iceland,' added Dr Spencer.
The rocks were once carved out of the landscape by glaciers on Greenland and would have become embedded in ice which was eventually set adrift as icebergs.
The ice-rafted rocks were likely deposited during the seventh century, coinciding with a major climate shift when temperatures warmed and the ground slowly rebounded after the heavy ice sheets melted.
Prof Gernon added: 'This timing coincides with a known major episode of ice-rafting, where vast chunks of ice break away from glaciers, drift across the ocean, and eventually melt, scattering debris along distant shores.'