The answer is desertification. Overgrazing, which refers to the excessive grazing of livestock on land, has contributed to the process of desertification in North Africa. Desertification is the gradual transformation of an area into a desert-like environment, typically caused by a combination of human activities and climate change. To arrive at this answer, we should consider the context of the given question and the impact of overgrazing on the environment in North Africa.
In North Africa, the environmental challenge that overgrazing has contributed to is desertification.
