Select key impacts over the African continent are highlighted in Figure 10-10. Water resources are a key vulnerability in Africa for water supply for household use and for agricultural and industrial use. In shared river basins, regional cooperation protocols minimize adverse impacts and potential for conflicts. Land use in many of Africa's large and shared basins has long-lasting impacts through modifications of the water budget and through chemical and sediment input into waterways. Water issues in urban and rural areas are likely to become more critical, given increasing and competing demands, as well as rapid population growth. Infrastructure to store and serve water in major urban areas is mostly overstretched in capacity, and extreme events such as floods that cause physical damage add to the problem. Monitoring of water levels and water use is very poor and limits analysis of vulnerability.

Figure 10-10: Selected key impacts for Africa.

There is wide consensus that climate change will worsen food security, mainly through increased extremes and temporal/spatial shifts. The continent already experiences a major deficit in food production in many areas, and potential declines in soil moisture will be an added burden. Food-insecure countries are at greater risk of adverse impacts of climate change.

Irreversible losses of biodiversity could be accelerated with climate change. Climate change is expected to lead to biome shifts, with drastic shifts of biodiversity-rich biomes such as the Succulent Karoo in South Africa, and many losses in species in other biomes. Analysis of potential biome shifts is possible in areas where good spatial databases of vegetation and biophysical variables and land use are available. It is expected that these analyses will improve as more data are available from new and better satellite sensing systems, as well as coordinated field studies in shared resource areas.

Changes in temperature and rainfall will have many negative impacts on human health. Changes in disease vector habitats will expose new populations to diseases such as malaria. Droughts and flooding, where sanitary infrastructure is inadequate, will result in increased frequency of water-borne diseases. Increased rainfall could lead to more frequent outbreaks of RVF. Many African nations do not have adequate financial resources for public health.

Sea-level rise, coastal erosion, saltwater intrusion, and flooding will have significant impacts for African communities and economies. Most of Africa's largest cities are along coasts and are highly vulnerable to extreme events, sea-level rise, and coastal erosion as a result of inadequate physical planning and escalating urban drift. Rapid unplanned expansion is likely to predispose large populations to infectious diseases from climate-related factors such as flooding.

Desertification is a critical threat to sustainable resource management in arid, semi-arid, and dry subhumid regions of Africa, undermining food and water security.

A diversity of constraints facing many nations limits overall adaptive capacity for Africa. Although there is uncertainty about what the future holds, Africa must start planning now to adapt to climate change. Current technologies and approaches—especially in agriculture and water—are unlikely to be adequate to meet projected demands, and increased climate variability will be an additional stress. It is unlikely that African countries on their own will have sufficient resources to respond effectively.

Climate change also offers some opportunities. The processes of adapting to global climate change, including technology transfer and carbon sequestration, offer new development pathways that could take advantage of Africa's resources and human potential. Regional cooperation in science, resource management, and development already are increasing, and access to international markets will diversify economies and increase food security.

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