Rome and More

In the Mediterranean, the time period between 1200 and 700 BCE is known as the Greek Dark Ages. Basically civilization there fell apart. Then around 750 BCE, civilization along the Mediterranean began to recover. Notice on the climate graph that the global temperature was rising.

First Mesopotamia evolved into the Persian Empire (612-330 BCE), then Greece recovered (750-146 BCE) and final the Roman Empire took over the entire Mediterranean (264 BCE-235 AD). By 450AD however, the glory of Rome was over. What happened?

Today, most historians would concede that no single factor can be blamed for the decline of this great civilization. As with all “extinctions” many things contributed to its fall. But perhaps one of the most interesting things about this period is that Rome was not the only empire to decline during this time.

Rome was not alone in its plight. In the years between 200 and 600 AD, empires were under siege all across the broad civilized belt that stretched from Rome in the west to China in the east.

Empires Besieged by the Editors of Time-Life Books

The world has grown old and lost its former vigor ... the mountains are gutted and give less marble, the mines are exhausted and give less silver and gold ... the fields lack farmers, the sea sailors, the encampments soldiers ... there is no longer any justice in judgments, competence in trades, discipline in daily life ... the Day of Judgment is at hand.

Cyprian, Bishop of Carthage, c. 250 AD

In China, the Han Dynasty, which had taken control of China sometime after the Warring States period and who had ruled successfully for nearly 400 years, fell apart and Chinese society was again plunged into a series of vicious civil wars. The political instability and conflict lasted from 189-589 AD. Nomads from the north (the Mongols and the Huns) took advantage of this turmoil, moved in, and took over.

By 500 AD the Gupta Empire in India (which included Indus) and New Persian Empire (which included Mesopotamia) were also toppled by the pressure of barbarian invasions. Like the time between 1200-1000 BC, there seemed to be a “general crisis of the civilized world”. This time the crisis also included China and again the “uncivilized” people from the Eurasian Steppes and the deserts of Arabia and North Africa were on the move. The previous crisis of 1200 BC was correlated with a changing global climate. Was there a climate change this time as well?

If you look back at our climate graph, you will see that indeed there was a climate change from 200-600 AD. For the first 200 years of Imperial Rome the climate was stable, then around 200 AD, the temperature began to drop. You will notice that the magnitude of the drop is not nearly as dramatic as that when the Near East Civilizations declined. Yet the average global temperature around 400 AD is about the same as it was around 2200 BC, the beginning of the 300 year drought in Mesopotamia. This probably means that the northern jet stream had moved enough to cause the same general effects that it had before.

The first people that would have felt the effects of these climate changes would have been the “uncivilized” nomads of the North and the South, Rome’s, India’s, Persia’s, and China’s “barbarians”. These people lived in very fragile ecosystems with minimal carrying capacity. In addition, there were a lot more people in both the civilized and uncivilized worlds in 200 AD than there were in 2000 BC. In 2000 BC the world population was only about 25 million people. In 200 AD there were over 200 million people. In both the civilized and uncivilized worlds, the populations were at or were approaching the carrying capacity of their respective environments. Even a relatively small decrease in the global climate would have lowered that carrying capacity enough to send the nomads in search of greener pastures, literally. The nomads that took over China, for example, turned farmland into pastures for their livestock. For the “civilized” farmers, the decreasing temperature would have meant decreasing yields and for the farmers of the Roman Empire, it must have meant rust epidemics.

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