First of all, most of them are already overpopulated. They are overpopulated by the simple crite- rion that they are not able to produce enough food to feed their populations. It is true that they have the money to buy food, but when food is no longer available for sale they will find the money rather indigestible. And they are overpopulated because they have exceeded the capacity of their environments to dispose of their wastes. Remember, overpopulation does not normally mean too many people for the area of a country, but too many people in relation to the necessities and amenities of life.
Overpopulation occurs when numbers threaten values.
ODCs also share with the UDCs serious problems of population distribution. Their urban centers are getting more and more crowded relative to the countryside. Indeed, social and environmental problems not only increase with growing population and urbanization, they tend to increase at an even faster rate. Adding more people to an area increases the damage done by each individual. Doubling the population normally much more than doubles environmental deterioration.