The document was published in the Proceedings of the National Academy of Sciences on Monday.
An international team of scientists and historians used an analysis of volcanic ash (tephras) found in ice cores from the Arctic to link the period of unexplained extreme climates in the Mediterranean, with the crater erupting forming Alaska Okmok volcano in 43 BCE.
“To find evidence of a volcano on the other side of the Earth erupted and contributed effectively to the disappearance of the Romans and the Egyptians, and the rise of the Roman Empire is fascinating,” said l lead author Joe McConnell of the Desert Research Institute (DRI) in central Reno, Nevada.
The advent of the Roman Empire also ended the Ptolemaic dynasty, the last of the pharaohs.
“It certainly shows how interconnected the world was even 2,000 years ago,” added McConnell.
He and Swiss researcher Michael Sigl began investigating the case when they found an exceptionally well-preserved layer of ash in an ice core from last year’s sample ice.
Further measurements were then made on ice cores from Greenland and Russia, some of which were drilled in the 1990s and stored in the archives.
They were able to make two separate eruptions: a powerful but localized and short-lived event in the early 45 BCE, followed by a much larger, increasingly prevalent event in 43 BCE, with fallout lasting more than two years.
A geochemical analysis was performed on the ash of samples found in the ice from the second eruption, and perfectly suited to the Okmok event – one of the largest eruptions in the past 2,500 years.
“The tephra match can’t get any better,” said volcanologist Gill Plunkett of Queen’s University in Belfast.
The team has gathered more evidence to support everyone, from the climate database tree-ring in Scandinavia, to the cave formations in northeast China.
These data were introduced into a climate model, suggesting that the two years after the eruption were some of the coldest in the Northern Hemisphere for 2,500 years.
Seasonal variations in average temperatures in May were, as much as seven degrees Celsius (13 degrees Fahrenheit) below normal for summer and fall, following the eruption, with fall precipitation up to 400% of normal in southern Europe.
“In the Mediterranean region, these humid and extremely cold conditions during the important agricultural season from spring to autumn probably reduced crop yields and worsened supply problems during the political upheavals of back then, “says classic archaeologist Andrew Wilson of the University of Oxford.
They also coincided with the failure of the Nile to flood the plains and the ensuing illness and famine, added Yale University historian Joe Manning.
The rash may also explain unusual atmospheric phenomena noted in the registers, such as solar halos, the sun sinking into the sky, or three suns appearing in the sky – a phenomenon known as a dog sun.
But the authors added that most of these sightings took place before the Alaska eruption and could be linked to the smallest eruption of Etna in 44 BCE.
McConnell said that, although many factors contributed to the fall of the Roman Republic and the Ptolemaic era, the eruption of Okmok played an important role, and helped fill a knowledge gap that had puzzled historians.
© Agence France-Presse