Rainfall

Rainfall in tropical and sub-tropical areas throughout the world is sporadic and highly variant. Its absence causes droughts; its overabundance causes flooding, soil leaching and erosion.

Heat

Most of Africa experiences tropical or sub-tropical heat. A hot climate can be a great disincentive for working, and insects and diseases thrive. Humidity is too high near the coast and in areas with high rainfall, and too low near the desert.

Desert

Much of Africa is desert or semi-desert and is unsuitable for farming and livestock. Global warming is increasing the size of Africa's deserts. Overpopulation in fragile environments such as the Sahel causes desertification through overfarming and overgrazing, leading to erosion, soil depletion and evaporation.

Isolation

Most of Africa is far from the coast, so it is not accessible by sea. Deserts, jungles, and tropical diseases have made land access difficult and dangerous. Much of Africa was isolated from the rest of the world until this century, making development through communication and trade difficult. These conditions also kept groups of African people divided and prevented the formation of centralised nation states with a common identity.

Economics

Because tropical soil is relatively infertile and population was low, there was little historical need for improved agricultural or industrial technology, and large surpluses were not produced. Economies were based on trade and small markets rather than through mass production, so Africa was slow to develop technology to industrialise.