Continental overview

The African continent includes some of the driest and some of the wettest locations on earth. Some locations receive several meters of rainfall each year; Mt. Cameroon receives over 10 m. Vast desert regions receive less than 5 mm on average. The major African deserts (Fig. 16.1) include the Sahara, the Somali-Chalbi and the Namib. Much of the rest of the continent is semi-arid, including such regions as the Sahel of West Africa, the Kalahari of southern Africa, and much of eastern Africa (Fig. 16.2).

A rather remarkable aspect of Africa’s climate is the tendency for climatic fluctuations to impact nearly the entire continent. The most common pattern is one of aridity throughout most of Africa, on a yearly (e.g., Fig. 21.8) or decadal basis. During the 1980s, for example, average rainfall for the decade was below normal throughout all but a few isolated sectors, mainly in the highlands of East Africa. Quite often the equatorial sector is out of phase with the rest of the continent. The 1950s, one of the wettest periods in the Sahel in recent times, showed such a pattern. Collectively, these large-scale anomaly patterns, extending over nearly 80° of latitude, implicate very large-scale controls on African climate.