Experts have time and again linked climate change to frightening large-scale effects on human civilizations. But how does a shifting climate make or break an empire, as demonstrated by history?
A new study published in the journal Nature Geoscience proposed the association between the Little Ice Age – ushered in by three major volcanic eruptions in 536, 540, and 547 A.D. – and historical events such as the fall of the Eastern Roman Empire and the rise of the Arab Empire.
The dramatic social change that swept through Europe and Asia at that same time included food shortages, a pandemic plague outbreak in Eastern Europe, the changing of Chinese dynasties, and the migration of Slavs and other groups across Europe. The collapse of the Eastern Roman Empire even paved the way for the reign of the Byzantine Empire.
Scientists cannot exactly pin all these upheavals down to the climatic shift of their era, but a connection is likely – albeit controversial.
“Ultimately, there can be very little doubt that these sorts of abrupt climatic events place great stress on societies, and can sometimes tip them over the edge,” said geographer Francis Ludlow of Ireland’s Trinity College Dublin.
The demise of what remained of the Roman Empire, for instance, which was then limited to the Mediterranean, was sped up by the loss of land and agricultural output during the mini ice age. Shorter growing seasons affected crops and led to famine as well as greater human vulnerability to disease.
The widespread food shortages are believed to contribute to the mobility of disease-bearing rodents into the empire – eventually reaching pandemic status as it conquered much of Europe, killing millions, and weakening the empire.
And it wasn’t just the Romans who bore the brunt, but also the Eastern Turk Empire around modern-era Mongolia and China’s Northern Wei and Sui dynasties.
Historians pointed to great political turmoil in central Asia during the same period, with a conflict brewing in the regimes of Northern China. Meanwhile, in Europe, Slavic groups were spreading across the continent probably due to social instability from crop shortages, famine, and outbreaks of illness.
But there were “winning” impacts, too. The study authors suggested that the climatic shift also paved the way for the rise of the Islamic Empire, where cooling-induced changes in precipitation trends possibly enabled scrub vegetation growth on the Arabian Peninsula.
As they noted in the paper, the area became less dry, and the increased vegetation could have assisted nomadic people and camel feeding. Larger camel herds may have helped transport Arab armies and their supplies during “substantial conquests” during the seventh century, allowing Arabs to move into Europe and take over the land of the Romans.
Other clear winners are the Lombards, who invaded Italy, as well as early Slavic tongues that apparently spread across from of the continent from their rather humble beginnings.
These interdisciplinary studies are deemed useful in understanding how humans might react or adapt to climate changes in the future.
