Central Africa is faced with similar challenges to other sub-regions in terms of climate variability: periodic extreme weather events, impacts of climate change on food production, sea level rise, and localized air quality problems in urban areas. These challenges are partly natural and require effective impact mitigation strategies but they are, in some cases, also exacerbated by human activities and thus require an integrated environmental management approach.
Rainfall and temperature patterns in Central Africa vary considerably, with unpredictable seasonal variations. Rainfall is relatively high and reliable over the central and coastal parts of the sub-region but tends to diminish and become more variable towards the north. For example, Douala, in coastal Cameroon, has an average rainfall of 3 850 mm/yr while Djamena, in Chad, receives only 500 mm/yr, and suffers periodic drought. Temperatures in the lowlying coastal forests vary little because persistent cloud keeps mean annual temperatures between 26°C and 28°C. In the high-relief mountainous areas, mean annual temperatures are low, between 19°C and 24°C. In the semi-arid zone of Cameroon and Chad, clear skies lead to strong insolation during the day and massive heat losses by emission of longer wavelength radiation at night.
Droughts in the Central African Sahelian zone have become more frequent since the late 1960s, and food security is declining, particularly among the poor who are forced to cultivate marginal lands and are unable to accumulate food reserves (IPCC 1998). Flooding is common in the more humid areas of Central Africa, especially where forests and natural vegetation have been cleared for cultivation or human settlements.
In the past 30 years, development policies and activities such as commercial logging, commercial or subsistence agriculture, and collection of firewood have led to extensive clearing of forests in Central Africa. These changes have disturbed the sub-region's microclimate, increasing vulnerability to rainfall fluctuations. Furthermore, the dense humid tropical forests of the sub-region are important sinks for atmospheric carbon dioxide (more so than forests of equal area in temperate zones). Reduction in their area therefore limits carbon sequestration and thus contributes to global climate change. Reduction of vegetation cover also exposes the soil and worsens the impacts of drought and flooding.
Central African countries have ratified the UNCCD, and Chad has also produced a National Action Plan. The Permanent Inter-State Committee for Drought Control in the Sahel (CILSS) has developed a sub-regional action plan to combat desertification (UNCCD 2001). CILSS and the Club du Sahel have also developed a new vision for food security in the Sahel, and have established a Food Crisis Prevention network to improve coordination between countries.