Climate Change, Illness Real Causes of Fall of Rome
Kyle Harper has produced a diligently researched and highly readable picture of the climate in the Roman Epoch and how it contributed to the collapse of the empire. Harper describes how, despite myriad other causes of the decline and fall of the empire, climate accompanied by its accomplices, pandemics and volcanism, laid low the mighty empire in a process that the Romans could not understand. The process is divided into the Roman Climate Optimum or RCO (200 B.C. to 150 A.D.) followed by the Late Roman Transition Period (150 to 450 A.D.) and the Late Antique Little Ice Age (450 A.D. to 700 A.D.). (p. 15)
Despite the appearance of champion emperors, Aurelian, Diocletian, Constantine the Great, Theodosius the Great and Justinian the Great, the empire succumbed to internal political chaos, demographic pressures and nature's inexorable changes. Further, the pathways that Roman road systems and the Roman network of sea transportation allowed unknown and virulent diseases to enter and spread throughout the empire. And, a period of “unparalleled volcanic violence” in the period 530-540, intensified the effects of the Late Antique Little Ice Age. By 476 A.D. the Western Empire had disintegrated. All that was left of the Western Empire were portions of Gaul and Italy. The boy emperor, Romulus Augustulus, was deposed and the Gothic Kingdom of Italy was proclaimed. The Eastern Empire survived and reconquered about one third of the former provinces of the west. But in the 6th century, the empire was hit by plague and natural disaster. And weakened, it was turned into a rump by the Arab onslaught of the 7th century, and by the 640s it had lost not only its levantine provinces but Egypt. It survived, waxing and waning (mostly waning), until 1453. It vanished in a blaze when Constantinople was captured by the Ottoman Turks, the last Emperor of the Romans dying in defense of his city.
The climate of Rome's transcontinental empire was greatly influenced by the wobbling of the earth’s axis (orbital forcing) and the increase or decrease in the level of radiation produced by the sun (insolation). Either could change the amount of the sun’s rays on the empire’s territory. These forces also affected the North Atlantic Oscillation that caused humid or arid conditions across the empire and well into Asia. Humid conditions caused too much rain damaging crops and causing floods. The Tiber River was notorious for flooding until the modern era. Aridity was also harmful to crops. An arid cycle could weaken the summer monsoon in the Indian Ocean and reduce the volume of the Nile River flood, further reducing food supplies. For about 350 years this weather system was highly favorable to the agriculturally based empire, the RCO. Circa 150 A.D. the system began to be less favorable, progressively cooler and dryer.
Harper relates that the Romans were not particularly healthy. Infant mortality was high (Marcus Aurelius and his wife, Faustina, had 14 children but only two survived into adulthood). Life expectancy may have been 20-30 years (p. 73). Despite an abundance of clean water, both crowded urban living around the empire and ignorance of germs vitiated Roman life. Fatal diarrhea may have been the greatest killer of Romans (p. 17). Malaria was rampant also. Cupped between the Seven Hills of Rome, the Forum Romanum was previously a swampy, lowland and the flooding of the Tiber left areas that bred mosquitos. But outbreaks were local or epidemic.
But Roman connectivity on land by road and on a sea cleared of pirates permitted diseases from outside the empire to enter and travel within it. Roman traders were everywhere, inside and outside the empire. And they brought back more than the riches of Africa and the East. The Romans maintained outposts in Mogadore (now Essaouira on the Atlantic coast of Morocco), and the Farasan Islands off the southwest coast of modern Saudi Arabia. The Eastern Empire maintained an outpost in what is now Abu Dahbi. Further, using the monsoons, Romans voyaged to India, Ceylon (known as Serendib to them), and to China trading for ivory, jewels, spices, and above all silk. In these travels, they were exposed to and carried various rodents homeward that were carriers of diseases unheard of in the empire. About 165 A.D. the outbreak of the Antonine Plague (probably smallpox) is documented by none other than Galen, a famous ancient medic. Saint Cyprian, a churchman of Carthage, left a narrative of the plague (a hemorrhagic fever) named after him that broke out around 249. The most devastating of all was Justinian’s Plague (bubonic plague) that appeared circa 541. All of these diseases took years to burn out and devastated the Roman population. The author references seven million dead from the Antonine Plague. Justinian’s Plague recurred until 749 (p. 236). Arriving by sea, the plagues were born inland on the road system and spread everywhere the empire controlled.
In the midst of this terrible plague, nature caused temperatures to drop precipitously and the sun to be dimmed. The year 536 A.D. is known as the “Year without a Summer” (p. 218). The North Atlantic Oscillation had flipped. Winter storms moved to the south. Temperature fell 2.5 degrees. Then in the same year a volcano erupted in the Northern Hemisphere followed by a second in the tropics in 539-540, and temperatures plunged another 2.7 degrees. “The decade 536-545 was the coldest decade of the last 2,000 years” (p. 253). The spume from these eruptions dimmed the sun. John of Ephesus wrote “The sun darkened and stayed darkened a year and a half…” (p. 251). Crop failure followed, and aridity caused the abandonment of cities in Roman Africa. Cisterns dried up in the Levant. The grain dole in Constantinople ceased. There was little left to tax in the agriculturally based empire and it became impossible to pay the army or raise the troops necessary to defend the empire because of demographic collapse. However, the empire was able to have one more victory.
In 621 Rome’s old enemy, Persia swept into the Levant and captured Egypt. The two powers had been fighting on and off since 53 B.C. The Persians were on the Bosphorus opposite Consantinople. The Emperor Heraclius bought them off and began a crash program to reform the army and raise money, some from melted down church treasure, and cut all non-military expenses. He launched an offensive that resulted in the decisive defeat of the Persians at Nineveh in 627, but the empire was prostrated and unable to withstand the onslaught of the Arabs.
Although the Eastern Empire carried on, its losses marked the end of the Roman order and way of life in the Mediterranean. The former provinces were replaced by the Latin west, the Greek east, and the various Islamic caliphates. However, our fascination with the Romans is seemingly limitless not only because of their achievements and their longevity but because of their legacy. Not the least of their legacy are the number of Roman monuments surrounding the Mediterranean basin. Perhaps history is really a study that provides us with vicarious experience based on the travails of those that came before.
Harper was able to clearly explain the various natural phenomena that contributed to the demise of the Roman Empire. Extensive notes and a large bibliography enable the reader to further explore the various scientific endeavors that led to the revelation that there was another dimension to the fall of Rome and a very long time line for its demise. Harper also credits the Romans with an adaptability that staved off disaster for hundreds of years. A reader may think that Harper anthropomorphised the germs and their vectors in their effects on the empire. Your reviewer does. Germs are not “evil” or “murderers” and they prepared no “ambushes.” They were and are merely organisms relying on instinct to survive and multiply.
Anyone interested in learning of the Roman Empire would do well to use maps. An excellent start is Michael Ditter’s "Map of the Roman Empire and Surrounding Territories" in 211 C.E. (Sardis Verlag: 2014). His map was prepared as he studied the Roman transportation network and the spread of the Antonine Plague. Atlases of the Empire are also helpful in understanding the changing size, political evolution, and vast expanse of the empire.
I try to avoid the term Byzantine, invented in the 16th century by a German scholar. I much prefer the Eastern or Later Roman Empire. The citizens of Constantinople always referred to themselves as Romans, Rhomaioi in Greek. To this day the small Orthodox population is referred to by their Turkish neighbors as Rumlar, Romans, in Turkish
