Remains of the Aqua Claudia aqueduct, near Rome (park of the aqueducts). • ISTOCKPHOTO Barbarians or bacilli? Invasions or viruses? Or both ? In other words, would climate change and pandemics have precipitated the fall of Rome? Drought, flood, smallpox and bubonic plague would be the names of its "four horsemen of the Apocalypse"? The past would then resonate strangely with the present. Not one, but crises It is a well-known fact:historians often look at the past inspired by the concerns of the time; the climate and viruses appear every day in the media and even guide public policies. Certainly, long before the current Covid pandemic, researchers have thought about diseases and their impact on history. Analyzing the climate as one of the factors in the fall of an empire is, on the other hand, a more innovative approach. In 2017, Kyle Harper, professor of history at the University of Oklahoma (United States), decided to look into these two phenomena to analyze their participation in the disintegration of the Roman Empire. His book, published and translated into French in 2019, and which will be released in paperback this year, opens up new perspectives. To fully understand the fall of the Roman Empire, one must imagine the causes of the crisis as the nine circles of Hell of Dante. The year 235 marks a symbolic break. The assassination of the Afro-Syrian emperor Severus Alexander inaugurates the waltz of the usurpers. Imperial power is unstable. The political crisis is the first circle of the general crisis. It engenders a military crisis. Poorly paid and occupied by civil wars, the soldiers defend the borders less well, which inevitably leads to a migration crisis. Barbarians – meaning all people living outside the borders of the Empire, the limes , and whose administrative language is neither Latin nor Greek – are raiding the provinces. Insecurity and looting generate a migration crisis, the third circle of hell. The decline in productivity, the result of the previous troubles, gave rise to a financial crisis. The increase in the tax burden fuels the social crisis. The superposition of all the causes mentioned above leads to a demographic crisis. The atmosphere is one of fear and superstition, the perfect breeding ground for a cultural crisis against a backdrop of religious change:Christianity with an eschatological vocation replaces paganism anchored in the philosophy of hic et nunc (" here and now "). But there are still two circles missing to imitate Hell of Dante:those of the climate crisis and the health crisis? The end of a mild climate The climate is by definition constantly changing. Its trends fluctuate depending on many elements such as solar activity. To know precisely the ancient climatic evolutions, Kyle Harper was interested in the cores taken from the glaciers and the seabed. The pile of sediments acts like a time machine. The Mediterranean era would have known an ideally hot and humid climate between the end of the Republic and the middle of the Early Empire. The Roman climatic optimum (or OCR) would have favored abundant harvests for several decades. The Empire was a veritable garden, not of Eden, but of the Hesperides, where nature generously offered its fruits. In fact, periods of famine were rare and short. The grain storage policy was sufficient to deal with classic climatic hazards. The state then intervened to rationalize distributions and freeze prices. Emperor Augustus (27 BC-14 AD) thus solved a shortage problem by temporarily chasing all foreigners from Rome to ensure bread for Roman citizens. Egypt was then the granary of the western Mediterranean. The abundant monsoon rains above the Blue Nile produce enough fertile silt to feed nearly half the Empire. But between 150 and 450, there would have been a kind of transitional period, during which the climate was gradually disorganized. Rainfall has been scarce. Droughts were more and more frequent and led to recurring and localized shortages, as in Cappadocia (a region of present-day Turkey) between 368 and 369. However, this drought had heavier repercussions on the southern part of the Empire. Regions north of the Sahara began to run out of water. The harvests were less good, and some cities were deserted. Egypt, the breadbasket of Rome, suffered greatly from climate change from the 380s. The flooding of the Nile floods the areas around the river less. Arable land is shrinking, and the whole Empire is starving. As a result, infant mortality increases. The Egypt we know today is beginning to take shape with its four colors, the blue of the sky, the azure of the Nile, the ocher of the desert and the green of the palm groves, now a minority. Also read The possibilities of the Nile Paradoxically, the increase in temperature and drought in North Africa is the corollary of a new Little Ice Age. This appeared between 450 and 700. The Western Roman Empire fell in 476, and the former imperial territory split into kingdoms ravaged by continual wars. The disintegration of the VI e century would have been precipitated by extreme weather events. The torrential rains in the northern part of the Mediterranean caused floods with catastrophic consequences in the cities:degradation of roads, sewer problems, increase in infectious diseases... In the east, the Byzantine Empire, thanks to its political structures strong, resists terrible plagues better. In addition, in 536, an abnormally high volcanic activity released enough gases and dust into the sky to cloud the air. For almost two years, Byzantine chroniclers such as John of Ephesus marveled at only seeing the sun for a few hours a day. The harvests suffer, and the vines only give a harsh wine. But the eastern part of the Empire is surprisingly resilient – a term dear to historian Kyle Harper, who uses it all over the garum sauces. – and is recovering quickly from these two years of bad harvests. At the mercy of the ravages of the plague While the climate contributed to aggravating the economic and financial crises, the demographic crisis at the end of Antiquity was more of a health origin. Ancient populations are used to living with disease. Parasites and minor gastric problems caused by worms and other tapeworms are the daily lot of everyone. In addition, Rome experiences a peak in mortality due to malaria every summer. The dozen aqueducts, hundreds of fountains and thermal baths make it a city of waters. Anopheles swarm and spread malaria. The second peak of mortality occurs in winter due to lung diseases. In addition, the Empire is periodically crossed by waves of epidemics whose incessant undertow takes its macabre lot. These pandemics are called pestis . The pestilence would be linked to the fetidity of the air which would carry miasmas. Emperor Titus faced, in 79 AD. BC, the eruption of Vesuvius and a wave of pestis . In both cases, he favored religious ceremonies and sacrifices to appease the decidedly angry gods. But this epidemic is nothing compared to the terrible “Antonine plague”, whose starting point would be the province of Seleucia of the Tigris in 165. Here again, everything begins with divine anger. The troops of Lucius Verus are said to have sacked the temple of Apollo with long hair. A strange pestilential cloud would then have escaped from the sacred building. Its miasma would have contaminated the soldiers, who, in turn, would have spread the disease along the paths taken to return to Rome. They would then have contributed to spreading the disease from east to west. Also read The plague and its remedies The Antonine plague which began in 165 was neither induced by the plague bacillus nor the first pandemic in history. It is however the most violent documented so far, since it generates a crisis lasting almost 30 years, not counting the aftershocks. According to specialists in ancient medicine, the evil sent by Apollo is smallpox, a very contagious disease, which the Romans knew well. Its mortality rate is estimated at 20%. Survivors are immune, but often disfigured by hideous pustule scars. The aftershocks of the disease, less and less deadly thanks to the growing share of the immunized population, extend over two centuries. The plague of Cyprian, between 249 and 262, is a violent accelerator of the crisis which begins in III e century. It begins in Alexandria and spreads along the shores of the Mediterranean following the trade routes. Symptoms of the disease are sudden fever and severe gastrointestinal disturbances with hemorrhage. The culprit virus is still not identified with certainty. We are thinking of a filovirus, or even the Ebola virus. In the affected provinces, it is the carnage. The city of Alexandria alone lost 60% of its population in a few years and went from 500,000 to 190,000 inhabitants. Athens registers 5,000 deaths a day. The disease seems to disappear in summer to better return in winter. Its lethality and virulence have greatly weakened the Empire. The Plague of Justinian is an even more violent drama. According to Kyle Harper's calculations, the bulk of the pandemic would have lasted from 527 to 565. But this disease would also have raged in waves until the VIII e century. This time – and for the first time in history – humanity faces the bubonic plague. Its fatality rate is estimated between 40 and 75%. Emperor Justinian himself contracted the disease in 542 and miraculously recovered, but the daily death toll in Constantinople is terrifying. According to Procopius of Caesarea, 5,000 to 10,000 corpses should have been evacuated from the capital of the Byzantine Empire per day... The figure is undoubtedly fanciful, but it attests to a very real slaughter. A technological regression The plague caused a significant population decline. The arms failed in the fields, and the famine came to mow down the most fragile. The Byzantine Empire has suffered, but Justinian's extraordinary willpower keeps it afloat. His desire to recompose the great Roman Empire through his conquests and his construction policy revitalized his territories, which were more resistant to climatic and health hazards. In the west, the repercussions of the generalized crisis lead to the entry into the Middle Ages. The cities had only a few thousand inhabitants left, whereas the Rome of the I st century had 1 million. Civil engineering loses its genius. Romanesque architecture is a technical regression alongside Roman marvels like the Pantheon in Rome or Hagia Sophia in Byzantium, whose cupolas defy the laws of gravity. Knowledge is reduced to scriptoria abbeys, when almost the entire population of the Early Empire deciphered at least the capital letters... From the technical point of view alone, the regression is obvious. The causes of the fall of the Empire are therefore multiple. This intertwining of factors formed a steamroller that no good political will could stop. Climatic disturbances and pandemics have aggravated the global crisis, but are not alone the gravediggers of Roman civilization. The hypertrophied and globalized Empire could not know an eternal rise. What goes up must come down. Find out more How the Roman Empire collapsed. Climate, disease and the fall of Rome, K. Harper, The Discovery (paperback), 2021. Timeline Around 150 AD. AD The Roman climatic optimum (a hot and humid period, which favored the development of the Empire) ends.165-190 The Antonine Plague, actually a smallpox epidemic, decimated the Roman Empire under the rulers of Marcus Aurelius and Commodus.235 The death of the last emperor of the Severan dynasty inaugurated a long period of political instability.Around 450 Beginning of the Little Ice Age which will end at the beginning of the VIII e century. Temperatures drop an average of 2.7°C.476 Fall of the Western Roman Empire. Only the eastern part survives, with Constantinople as its capital.530-540 A period of intense volcanic activity heavily affects the climate, crops and drinking water supplies.541 Beginning of the Justinian plague, the first plague pandemic in history, the aftershocks of which would span three centuries. The Golden Age of Climate Optimum Today, everyone knows that the climate is fickle. If recent human activity contributes to its variations, many other factors come into play. The Roman Empire experienced an extremely favorable climate for its development between 200 BC. AD and 150 AD. These three and a half centuries during which the weather was stable, hot and humid in the Mediterranean received the name of “Roman climatic optimum” (OCR). Traces of this can be found in the study of seabed sediments and core samples from Alpine glaciers. This explains, for example, why Hannibal was able to cross the Alps with elephants and why the harvests were lastingly abundant, especially in Egypt where the rains were heavy enough to generate high floods rich in fertile silt. OCR gradually disappeared during II e and III e centuries.Also read Climate:heat stroke in the Middle Ages A dense network of cities and roads Ancient Mediterranean civilizations were urban. During the Roman Empire, the countryside with its agricultural lands was largely populated by slaves attached to large estates and by retired legionnaires. The majority of the population lived in cities. These lined the sprawling road network built across Imperial territory. Goods and soldiers transited on these routes, of which there are still many archaeological remains. Apart from the winter months when the sea was “closed”, the Mediterranean ports formed another network of incredible density. The routes continued beyond the borders of the Empire to the Far East. The Urbs , the capital, was at the heart of many interconnections, hence the expression:all roads lead to Rome. Smaller and smaller Romans From the beginning of the Empire until its fall, Italians measured an average of 1.64 m and Italian women, 1.52 m. The researchers found that they had lost a few centimeters compared to the period between the Bronze Age and the Republic. A lower quality diet could explain this decline, but the study of bones from necropolises shows that even modest Romans had a diversified and meaty diet. Other factors such as disease can stunt growth by putting a strain on the body during childhood. When historian Kyle Harper explains that the size of the Bretons shrank after the Roman conquest, because the Romans would have impoverished them and would have given them diseases, one wonders if he is not placing on the Romans the behavior of the American settlers with the Indians… All sick from public baths? According to historian Kyle Harper, the Roman baths were a veritable melting pot of culture. However, if these establishments had been as dangerous as the American suggests, they would not have been one of the symbols of Roman civilization. Admittedly, chlorine was not yet used. But remember that the water was constantly flowing in the basins, bathtubs and swimming pools. Some thermal baths, such as those in Bath in England, operated with water from naturally hot springs rich in minerals. In addition, our distant ancestors had a stronger immune system than ours, because we are raised today in very sanitized environments. The greatest danger of the thermal baths was above all the repeated rubbing of the strigil on the skin, which it irritated by scraping its hydrolipidic film. The use of strigil thus favored dermatological diseases.
