That is probably true but you are thinking of a natural ice age what I am thinking of is a supernatural ice age, the temperature dropping 30-40 or more degrees in one hundred years. Nature don't have the time to adept itself in that time and a loot of plants and animals will die because of the cold, people will flee there ancestors land since it can no longer support them and there cloths can no longer protect them from the cold. They will move to warmer land were they will try to make living and if somebody is already living there they will try to take it from them