https://quillette.com/2020/04/11/the-fate-of-rome-climate-disease-and-the-end-of-an-empire-a-review/
A review of The Fate of Rome: Climate, Disease and the End of an Empire by Kyle Harper, Princeton University Press, 417 pages (October 2017)
Why did the Roman Empire fall? The classic answer is given by Edward Gibbon (1737 — 1794), in chapter 38 of the third volume of The History of the Fall and Decline of the Roman Empire (1776 — 1789):
The decline of Rome was the natural and inevitable effect of immoderate greatness. Prosperity ripened the principle of decay; the causes of destruction multiplied with the extent of conquest; and as soon as time or accident had removed the artificial supports, the stupendous fabric yielded to the pressure of its own weight.
Kyle Harper, Senior Vice President and Provost of the University of Oklahoma, seeks to complement Gibbon’s account by emphasising the role of nature, and specifically climate change and infectious disease, in the fall of Rome in his provocative, exceptionally well-written book The Fate of Rome: Climate, Disease and the End of an Empire. Is Harper correct? Were plagues and climate events fatal for Rome?
Harper accepts the conventional view that Rome’s civilizational collapse began in the later second century AD, accelerated amidst chaos and bloodshed during the third century, and culminated in the humiliations of the fifth century, when Rome was famously sacked by barbarians, and the last, weak, insignificant Roman Emperor was pushed off the throne in AD 476.
The Fate of Rome does not neglect literary and archival sources, or archaeological evidence related to the fall of Rome; but Harper thinks historians have neglected “natural archives,” which is how he describes genome evidence from DNA, biological data (as found in bones and teeth of excavated ancient skeletons), tree rings, glaciers, marine sediments, and all other materials studied by environmental historians, geochemists, and other scientific researchers: