If you want to understand the collapse of Rome I suggest reading “The Fate of Rome: Climate, Disease, and the End of an Empire” (2017). If you think you see parallels between the politics of the Late Empire and today, you will really be surprised by the parallels of climate change and pandemic. One of the key points of the book is that the fate of Rome was tied inextricably to fluctuations of the climate and to outbreaks of disease.
For example, the battle of Adrianople in 378 AD is regarded as on of Rome’s worst defeats ever. At Adrianople the Romans lost an estimated 20,000 men in a single day and the Goths pushed their way into the Empire. It was a disaster for Rome that it never recovered from, but it didn’t happen in a vacuum. It came at the end of two centuries of plague, deteriorating climate, and economic contraction.
The Antonine Plague:
The Antonine Plague was the first pandemic in history and it happened because the Romans created a world in which pandemic became possible. Cities with dense populations connected by highly trafficked trade links bringing in goods and people from all over the world made the Mediterranean a vast petri dish waiting for something deadly to fall into (sound familiar?). In 165 AD something did.
Starting in 165 AD the Antonine plague is estimated to have killed 7,000,000 in the first years that it hit the empire (165–180 AD). It could have been measles but it was probably smallpox. It showed up in the cities of the Middle East and was probably carried by the Roman Army and by merchants throughout the Empire.
According to the Roman historian Dio Cassius (155–235), when the disease returned to Rome in 177 AD it caused up to 2,000 deaths a day in Rome and had a mortality rate of about 25% The total number of deaths in this first wave have been estimated at 15 million. With the disease killing as much as one-third of the population in some areas and devastating the Roman army.
What’s worse, is that there wasn’t just one hit and then it was over. The plague would burn through one location. Then radiate out from there to other cities and the countryside as people tried to flee from it. Because of the slower travel times this dispersal and radiation of the disease took decades to play out.
After 165 there was always plague going on in the Empire.
Including an outbreak that was especially severe known as the Plague of Cyprian that ran from 251–ca. 270. The severe devastation to the European population from the two plagues may indicate that people had no previous exposure to this disease, so they were in essence “virgin field” epidemics.
Finally in 541 AD, the first great pandemic of Yersina pestis, or bubonic plague struck the Mediterranean. It too was devastating and it would linger for more than two centuries. Three major waves of plagues that over a 600 year period caused a decline in population of about 50%.
The Empire’s most prosperous period, it is generally agreed, was between 96 and 180 AD. That period, when the Roman project was at its most healthy — also coincided with the Roman Climate Optimum, which ran from 200 BC to 150 AD. This was a period when the weather warmed up.
Pliny the Elder, writing in the first century AD, described how beech trees, which used to grow only in the lowlands, started climbing up mountains as the temperature rose. Olives and vines were grown further and further north. The Empire became a giant greenhouse.
The weather started deteriorating in 150 AD. Known as the ‘Roman Transitional Period’ the weather got worse year after year for 250 years. Until it hit temperature lows in the ‘Late Antique Little Ice Age’, from 450–700 AD, when the Empire fell apart.
The changing climate brought famines, some of them severe. In Egypt in 244 AD, the Nile failed to rise and irrigate neighboring fields, and was weak in the following two years. A population weakened by widespread malnutrition was vulnerable to disease and in 249 AD the Plague of Cyprian struck. Political instability fueled by hunger and depopulation led to a mini-collapse sometimes called the ‘first fall’ of the Empire.
Unfortunately for the Romans, things never got any better. Constant plagues were depopulating the empire and the climate change made it harder and harder to feed the people who were still left. Doesn’t that sound familiar to what we are on the verge of today?
By 650, the heady days of Roman glory were long gone: the population of the Mediterranean basin, which had been 75 million in the 2nd century AD, collapsed to half that. Rome, capitol of the world, once home to a million people was now inhabited by only 20,000 who lived among the ruins.
Armies need to be paid for, as do fortifications like Hadrian’s Wall and the Limes in Germany. Roads and other public works need to be maintained and navies need to be built up and maintained so that piracy is suppressed and trade flourishes. Climate change by itself would have been stressful on the economics of the Roman state. As lands became less productive tax revenues would also have fallen. As we are learning ourselves paying for everything becomes harder when the weather is working against you.
Add to that, the devastating depopulation of the plagues that burned through the Mediterranean for basically 400 years (150–550 AD) and the surprise isn’t that the economy contracted, the surprise is that it didn’t collapse completely. Imperial Rome had some serious leadership problems. Instability at the top undoubtedly contributed to Rome’s decline, but looming over everything was the continual decline of population in this period.
As population declined and revenues shrunk, the state simply wasn’t able to keep funding the troop levels and fortifications that were built during the period of expansion. Areas were depopulated and contraction led to some lands being abandoned. Once economic contraction starts a negative feedback kicks in and it becomes next to impossible for the state to maintain itself. It becomes permanently revenue starved and “hollows out” as it cuts and cuts trying to keep the essentials going. Collapse becomes possible if additional stress gets applied to the state before a period of recovery and regrowth has a chance to happen.
As we all know, for Rome, that stress would take the form of hungry “barbarian” peoples (made desperate by the effects of climate change on their homelands) trying to push into what they saw has the prosperity and safety of the Roman Empire.
Essentially the Roman state got worn away by climate change, plague, and the economic instability these caused. The victory of the Goths in Adrianople, and the later victories of the Franks, and the Vandals, the Lombards, and the Huns (all of whom were pushing on the Romans because climate change was pushing them as well) were possible because the Roman state was a shadow of what it had been at it’s peak.
Like I said, the parallels are eerie.