Pandemics then and now
Kyle Harper makes an interesting point in the prologue of his book that the fall of the Roman Empire occurred in conjunction with a series of naturally-occurring changes in the climate, which likely exacerbated the conditions in which Rome fell. Notably, one of these conditions was the onset of a smallpox-induced pandemic, which ravaged the empire and carried serious consequences, ultimately allowing the Gothic tribes to claim victory in Rome. Harper explains that the consequences of human actions--especially the stirring up of various infectious diseases via overuse of the land--and climate change combined to ultimately overturn Rome's power within the known world.
This calls into the spotlight a comparison of the fall of Rome to the current situation seen worldwide today. The twenty-first century is facing climate changing at an unprecedented and increasing speed, and a pandemic has claimed millions of lives around the globe. While I am not convinced that these circumstances inherently mean that powerful nations will fall, it is worth noting that many of the causes of the Roman catastrophe and the current catastrophe have direct ties to how these powerful nations first interacted with their surrounding environments. These catastrophes are both due partly to chance and exacerbated by human actions. Once again, the more things change, the more they stay the same.