Late Antiquity Little Ice Age Triggered Plague, Decline of Empires, and Migration
When people think of climate change, most think of rising temperatures, drought, and an increase in storms—the type of climate change Earth is undergoing now. A lot has also been written about how drought and its ills caused empires and kingdoms to fail.
Now, a group of researchers looked at another type of climate change—a mini ice age—that they say caused some empires in Eurasia, including the Roman, to decline or fall and may have brought plague-carrying rats to Eastern Europe.
The authors, led by Ulf Büntgen of the Swiss Federal Research Institute, wrote an article for the journal Nature Geoscience ( abstract) saying the climatic changes caused “societal reorganizations” in Asia and Europe.
“In particular, the sixth century coincides with rising and falling civilizations, pandemics, human migration and political turmoil,” the 16 co-authors’ abstract states.
In a 1490s painting, St. Sebastian pleads with God for the life of a gravedigger stricken by plague during the 7th century Plague of Justinian, which the authors say may have been caused by climate change. ( Public Domain )
The researchers who worked on the study include climatologists, geographers, historians, physicists, and a linguist. They looked at tree-ring growth from the Russian Altai Mountains and European Alps to estimate summer temperatures over 2,000 years.
They say the Little Ice Age of 1450 to the late 1800s AD was not as severe as the one that struck Eurasia in the 6th and 7th centuries.
Their abstract states:
“We find an unprecedented, long-lasting and spatially synchronized cooling following a cluster of large volcanic eruptions in 536, 540 and 547 AD, which was probably sustained by ocean and sea-ice feedbacks, as well as a solar minimum. We thus identify the interval from 536 to about 660 AD as the Late Antique Little Ice Age. Spanning most of the Northern Hemisphere, we suggest that this cold phase be considered as an additional environmental factor contributing to the establishment of the Justinian plague, transformation of the eastern Roman Empire and collapse of the Sasanian Empire, movements out of the Asian steppe and Arabian Peninsula, spread of Slavic-speaking peoples and political upheavals in China.”
Byzantine Emperor Heraclius submitting the last important king of the Sasanian Empire, king Khosrau (Khosrow) II (reigned 590-628 AD). ( Public Domain )
“Based on this study, we would say this episode was the coolest over the last 2000 years,” Dr. Büntgen told New Scientist .
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Summers as much as 4 degrees Celsius (7.2 degrees Fahrenheit) cooler resulted from volcanic particles obscuring the sunlight reaching the Earth. The average temperature difference probably was about 2 degrees Celsius (4 degrees F) below temperatures from the standard reference point—1961 to 1990.
The dramatic eruption of Mt Vesuvius came earlier than the Late Antique Little Ice Age, in 79 AD. ( Public Domain )
One effect of the change in temperatures and weather patterns was that the remaining Roman Empire, then restricted to Mediterranean areas, lost even more land and power. A shorter growing season may have reduced crops and caused famine. Famished people also are more susceptible to disease. Another effect was the possible introduction of disease-bearing rodents into the empire.
Some people apparently benefited from the little ice age. The Arabian Peninsula may have become less dry, increasing vegetation and helping nomads who needed to feed camels and, perhaps, prompting Arabs to migrate to Europe and take Roman lands. New Scientist also reports that the Germanic Lombards invaded Italy and took control from 568 to 774. And the early Slavic languages, whose homeland is not known, spread across much of continental Europe during this time.
This period of history is known as Late Antiquity. Büntgen et. al. named the period the Late Antique Little Ice Age .
Featured image: It’s possible Mount Tavurvur, a part of the Rabaul caldera volcano in Papua, New Guinea, played a role in the climate change beginning 536 AD. Others have theorized that dust thrown in the air by crashing meteorites played a role in the climate change. ( Taro Taylor/CC BY 2.0 )
By Mark Miller