late antique little ice age
February 8, 2016

Late Antique Little Ice Age associated with fall of eastern Roman Empire, rise of Arab Empire

The last three decades may have the warmest summers seen in Europe of the course of two millennia, but now researchers have identified the coldest temperatures in the same time frame—and discovered they coincide with an extremely riotous time in history.

In fact, these cold temperatures were so cold and lasted so long that the researchers believe that have identified a previously unrecognized mini ice age. Lasting from 536-660 CE, they have dubbed this cold snap the Late Antique Little Ice Age—as the time period in which it fell correlates to the end of the Age of Antiquity.

According to the study, which is published in Nature Geoscience, the researchers investigated tree ring data from 150 living and 500 dead trees from the Russian Altai-Sayan Mountains, whose tissue chronicled temperatures from between 358 BCE to 2011 CE. They discovered that the average temperature fell by around 5.4 degrees Fahrenheit (3 degrees Celsius) colder than today’s average in this Little Ice Age—which may seem small, but of the 20 coldest summers in that region within a 2,300-year span, 13 occurred consecutively in this 120-year time period.

Or, as lead author Ulf Büntgen from the Swiss Federal Research Institute put it, "This was the most dramatic cooling in the Northern Hemisphere in the past 2000 years."

This Ice Age seems to have begun thanks to three volcanic eruptions that occurred in quick succession: one in 536, another in 540, and the last in 547 CE. These eruptions spewed large amounts of sulfate aerosols, which entered the atmosphere and blocked out sunlight by reflecting it back into space, thereby dropping temperatures globally. The researchers think that these events coincided with the solar minimum, which paired with the reactions of sea ice drew out this temperature plunge across the sixth and seventh centuries.

The other shoe drops

But the researchers have uncovered something even more fascinating than a new mini-Ice Age, because they believe that this temperature drop directly changed the course of human history.

In fact, they believe that the temperature change led to the decline of the eastern Roman Empire and the rise of the Arab Empire.

After the team—which consisted of naturalists, historians, and linguists—mapped the new climate information against the turbulent events of the mid-fifth century in and around the eastern Roman Empire, they were able to draw links between the climate change and historical events.

"With so many variables, we must remain cautious about environmental cause and political effect, but it is striking how closely this climate change aligns with major upheavals across several regions," said Büntgen.

For example: Following the eruptions, first went the food. As temperatures plunged, food supplies did too—or so they guessed, as a major famine struck the region in the time immediately after the eruptions. And then, directly following (and perhaps exacerbated by) the famine, plague struck—as in the Justinian Plague, which killed millions of people across the Mediterranean.

Meanwhile...

At the same time in central Asia, multiple tribes began to migrate eastwards towards China, likely because their pasturelands were in decline thanks to cooler temperatures. These nomadic tribes clashed with local ruling powers in the steppes of northern China. Then, these populations allied themselves with the Eastern Romans to bring down the Sasanian Empire in Persia—clearing the way for the Arab Empire to rise up in its wake.

Meanwhile, to the south of the Eastern Empire, the Arabian Peninsula began receiving more rain than usual, allowing more vegetation to grow than before. The researchers believe this boom in plant life allowed the Arab armies to grow in size, as the increase in food sources meant they could use more camels on their campaigns. Naturally, this led to more successes for the Arab Empire, which could now being fill the void left by the Sasanian Empire.

Or in short, the researchers believe the Late Antique Little Ice Age played an enormous role in shaping the events of the time period.

“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,” they wrote.

All of which raises the question: In our current dramatic climate shift, who will rise?

And who will fall?

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Feature Image: Thinkstock