There are remarkably few studies available that examine the impacts of climate change on energy use in Africa (but see a recent regional assessment by Warren et al., 2006). However, even in the absence of climate change, a number of changes are expected in the energy sector. Africa’s recent and rapid urban growth (UNEP, 2005) will lead to increases in aggregate commercial energy demand and emissions levels (Davidson et al., 2003), as well as extensive land-use and land-cover changes, especially from largely uncontrolled urban, peri-urban and rural settlements (UNEP/GRID-Arendal, 2002; du Plessis et al., 2003). These changes will alter existing surface microclimates and hydrology and will possibly exacerbate the scope and scale of climate-change impacts.
Vigorous debate among those working in the health sector has improved our understanding of the links between climate variability (including extreme weather events) and infectious diseases (van Lieshout et al., 2004; Epstein and Mills, 2005; McMichael et al., 2006; Pascual et al., 2006; Patz and Olson, 2006). Despite various contentious issues (see Section 126.96.36.199), new assessments of the role of climate change impacts on health have emerged since the TAR. Results from the “Mapping Malaria Risk in Africa” project (MARA/ARMA) show a possible expansion and contraction, depending on location, of climatically suitable areas for malaria by 2020, 2050 and 2080 (Thomas et al., 2004). By 2050 and continuing into 2080, for example, a large part of the western Sahel and much of southern central Africa is shown to be likely to become unsuitable for malaria transmission. Other assessments (e.g., Hartmann et al., 2002), using 16 climate-change scenarios, show that by 2100, changes in temperature and precipitation could alter the geographical distribution of malaria in Zimbabwe, with previously unsuitable areas of dense human population becoming suitable for transmission. Strong southward expansion of the transmission zone will probably continue into South Africa.
Using parasite survey data in conjunction with results from the HadCM3 GCM, projected scenarios estimate a 5-7% potential increase (mainly altitudinal) in malaria distribution, with little increase in the latitudinal extent of the disease by 2100 (Tanser et al., 2003). Previously malaria-free highland areas in Ethiopia, Kenya, Rwanda and Burundi could also experience modest incursions of malaria by the 2050s, with conditions for transmission becoming highly suitable by the 2080s. By this period, areas currently with low rates of malaria transmission in central Somalia and the Angolan highlands could also become highly suitable. Among all scenarios, the highlands of eastern Africa and areas of southern Africa are likely to become more suitable for transmission (Hartmann et al., 2002).
As the rate of malaria transmission increases in the highlands, the likelihood of epidemics may increase due to the lack of protective genetic modifications in the newly-affected populations. Severe malaria-associated disease is more common in areas of low to moderate transmission, such as the highlands of East Africa and other areas of seasonal transmission. An epidemic in Rwanda, for example, led to a four-fold increase in malaria admissions among pregnant women and a five-fold increase in maternal deaths due to malaria (Hammerich et al., 2002). The social and economic costs of malaria are also huge and include considerable costs to individuals and households as well as high costs at community and national levels (Holding and Snow, 2001; Utzinger et al., 2001; Malaney et al., 2004).
Climate variability may also interact with other background stresses and additional vulnerabilities such as immuno-compromised populations (HIV/AIDS) and conflict and war (Harrus and Baneth, 2005) in the future, resulting in increased susceptibility and risk of other infectious diseases (e.g., cholera) and malnutrition. The potential for climate change to intensify or alter flood patterns may become a major additional driver of future health risks from flooding (Few et al., 2004). The probability that sea-level rise could increase flooding, particularly on the coasts of eastern Africa (Nicholls, 2004), may also have implications for health (McMichael et al., 2006).
Relatively fewer assessments of possible future changes in animal health arising from climate variability and change have been undertaken. The demographic impacts on trypanosomiasis, for example, can arise through modification of the habitats suitable for the tsetse fly. These modifications can be further exacerbated by climate variability and climate change. Climate change is also expected to affect both pathogen and vector habitat suitability through changes in moisture and temperature (Baylis and Githeko, 2006). Changes in disease distribution, range, prevalence, incidence and seasonality can all be expected. However, there is low certainty about the degree of change. Rift Valley Fever epidemics, evident during the 1997/98 El Niño event in East Africa and associated with flooding, could increase with a higher frequency of El Niño events. Finally, heat stress and drought are likely to have further negative impacts on animal health and production of dairy products, as already observed in the USA (St-Pierre et al., 2003; see also Warren et al., 2006).