The impending destruction of Jerusalem is designed to be so severe that no one could mistake it for a natural disaster or a random stroke of bad luck. Instead, it will be a clear, deliberate decree orchestrated by God. To ensure the world recognizes His direct involvement, the punishment will be far worse than any ordinary catastrophe.
God will unleash devastating forces of famine that act like targeted weapons, representing deep suffering and natural blights such as crop disease, mildew, and locust swarms that wipe out the harvest [מצודת ציון, רד״ק]. Historically, these destructive forces were directed at the surrounding nations. Now, however, those exact plagues will be intentionally redirected to strike Israel [מלבי״ם, מצודת דוד, אברבנאל, ביאור שטיינזלץ].
The primary approach among commentators is that God will multiply the severity of this famine far beyond anything the other nations have ever experienced, forcing the world to acknowledge His hand in the events [מלבי״ם, מצודת דוד, אברבנאל]. This intensified suffering will take various forms. Some explain that it will manifest as a complete drought, where the earth produces absolutely no crops [רד״ק]. Others suggest that the crisis will not necessarily be a lack of physical food, but rather a severe economic collapse. In this scenario, people will simply have no money left to purchase whatever food is available, a situation considered even more painful than a high cost of living [רש״י, רד״ק, חומת אנך].
Ultimately, food serves as the basic support of human survival, much like a walking stick a person leans on for stability. God will completely shatter this essential support [רש״י, מצודת ציון, מצודת דוד]. Even if an individual somehow manages to secure the funds to buy grain from foreign lands, survival will still be impossible, as the tight enemy siege surrounding the city will block any supplies from entering [רד״ק].