GAW Report No. 205 - IGAC Project

CHAPTER 2 - AFRICAFigure 3 displays black carbon anthropogenic emissions from a regional emission inventoryin different sectors (traffic, biofuel, power plant, industries) and different African regions.Anthropogenic Black carbon (BC) emissions in Africa are of the order of 0.68 TgC (about 13% ofglobal emissions), whereas African anthropogenic organic carbon (OC) emissions are above 40%.The same pattern occurs in West, Central and South Africa, with predominance of domestic fireemissions and a moderate traffic contribution. It is also important to note the contribution ofindustrial activities and power plant emissions in South Africa. In Northern Africa, traffic is thepredominant emission source with a smaller contribution of domestic fires and industrial activities.Total budgets for every region are of the same order, with enhanced emissions in West Africa ascompared to other areas. With such differences in mind between African areas, this chapter willcomprise three parts, respectively relating to megacities in (1) West Africa, (2) South Africa and (3)Northern Africa. In each part, specific features of some cities will be presented, followed bydescriptions of on emission sources, atmospheric pollution and the impacts on health.Figure 3 - Black carbon emission (in tons of carbon) in different sectors (traffic (C), biofuel (D), power plant (PPLT),industries (I)) and different African regions [Liousse et al., 2012; Assamoi, PhD 2011]2.2 WEST AFRICA2.2.1 Specific features of some West African citiesIn West Africa, climatic domains range from wet Tropics with heavy rainfall to arid deserts.Climate is wetter and humid in the South, getting drier and arid when moving north. So, there aretwo categories of cities: “wetter” ones along the Gulf of Guinea and others, in drier sahelian areas.After the independencies in the 1960’s, large cities have been very attractive forneighbouring and rural population, leading to a net demographic densification, especially in coastalcities. Such unplanned, spontaneous city sprawl has led to socio-economical difficulties (lack ofjobs, violence, etc.) with accompanying extreme poverty and the formation of shantytowns at theperiphery of many cities. Consequently, there is a lack of basic amenities such as drinkable water,sewage systems, waste treatment, electricity, roads, urban transportation and even schools.This also causes an intense degradation of suburban environments. One of the mainreasons for the degradation, noticeable in Figure 2 and 3 and stressed in Table 1 for CO andvolatile organic compound (VOC) emissions in Ouagadougou, is the increase in biofuel use, themain source of energy for cooking and heating. Gas energy is still a luxury in the absence ofgeneralized wind or solar energy use. Initiatives already exist to test cleaner fuels (such as gasfuels) in new cook stoves in Ghana [Bawakyillenuo, 2012]. Another pollution source is related to30