The severity of the volcanic winter that would follow a supervolcano eruption is the subject of considerable debate in the scientific community. The most commonly held view is that a volcanic winter would lower the average global temperature by 5 – 9° F for a period of 6 to 10 years. Other scientists believe the temperature change would be much less drastic, on the order of 2° F. Yet another hypothesis, the controversial Toba Catastrophe Theory, holds that a such an eruption could trigger a volcanic winter so severe that it would lead to an ice age. As a novelist, I’ve chosen to depict the most severe—and dramatic—possibility.