The fall of the Roman Empire is one of the most widely debated issues in ancient history and scholars from around the world have expressed almost every possible point of view. Although there were many underlying problems with the Roman Empire that led to its decline and eventual fall, the main problems, in my opinion, were Rome's economic situation, the weakening of Rome's military, and Rome's overall gradual decline. Furthermore, the Barbarians were one of the leading factors of Rome's demise.
One of the main causes of economic difficulty in the empire was the sheer lack of circulating currency in the Western Empire. In all likelihood, enough currency would have been available, however, wholesale hoarding of bullion by individual Roman citizens, and widespread looting by the Barbarians drained Rome's once wealthy treasury. Due to these two factors along with the enormous trade deficit with the Eastern Empire stunted the growth of wealth in the western regions. (Gibbon).
Surprisingly, the climate of the Mediterranean may have contributed to the economic collapse in Rome. As the climate became more volatile, it began to alternate annually between hot droughts and cold, rainy seasons. Obviously, this would diminish crop yields and forced the Romans to start irrigation projects on lands that were previously self-sufficient. In order to build irrigation ditches, huge amounts of water are needed and soon Rome's water supply began to stagnate. Once Rome's water became stagnant, the environment was primed for malaria-carrying mosquitoes to invade. Eventually, malaria reached epidemic levels and decimated Rome's population. However, even if the malaria, the agricultural problems, or the invasion of barbarians never took place, the drastic changes in the climate would still have led to Rome's economic problems. Surprisingly, due to the climate changes, the average Roman citizen's physical and mental abilities were becoming increasingly difficult to sustain at the level at which they needed to be to keep Rome thriving.