“There are two things everybody knows about Roman Empire: that it was an invincible superpower, and that when it fell, it fell hard. Usually the death of the empire gets blamed on barbarian hordes, imperial decadence, or on simple exhaustion. But one factor in Rome’s slow tumble into chaos has often been ignored: the role of the natural world. In The Fate of Rome: Climate, Disease, and the End of an Empire, published by Princeton University Press in October, classicist Kyle Harper lays out the ways that climate change and emergent epidemics conspired to hamstring the first globalized European empire.
The Holocene—the era between the last great Ice Ages and the present—has been a comparatively stable climatic stage for humanity. But that comparatively is crucial: natural processes like volcanic eruptions, orbital cycles, and changes in solar output have lead to rapid changes in climate for various parts of the world. The Romans, Harper argues, were lucky enough to start building their empire at a time of remarkable plenty. The period between 200 BC and AD 150, known as the Roman Climate Optimum, saw a warm and wet climate settle over the temperamental Mediterranean. The resulting environment would have looked fairly different from the modern world. In the Egyptian coastal city of Alexandria, it rained every month of the year but August—today, Alexandria gets a combined day of rain from May to September. Naturalist Pliny the Elder noted that Beech trees were advancing from the lowlands into the mountains, and off-handedly recorded the presence of elephants and lions in the Atlas Mountains of North Africa. Glaciers in the Alps retreated to levels seldom seen before the 21st century; vines and olives were cultivated further north than ever before…”