IPCC Climate Change Africa:
By 2020, between 75 and 250 million people are projected to be exposed to an increase of water stress due to global warming. If this is coupled with increased demand, then it will adversely affect livelihoods and exacerbate water-related problems.
Agricultural production, including access to food, in many African countries and regions is projected to be severely compromised by climate variability and change. The area suitable for agriculture, the length of growing seasons and yield potential, particularly along the margins of semi-arid and arid areas, are expected to decrease. This would further adversely affect food security and exacerbate malnutrition in the continent. In some countries, yields from rain-fed agriculture could be reduced by up to 50% by 2020.
Local food supplies are projected to be negatively affected by decreasing fisheries resources in large lakes due to rising water temperatures, which may be exacerbated by continued over-fishing.
Towards the end of the 21st century, projected sea-level rise will affect low-lying coastal areas with large populations. [This is already happening in Niger ] The cost of adaptation could amount to at least 5-10% of GDP. Mangroves and coral reefs are projected to be further degraded, with additional consequences for fisheries and tourism.
New studies confirm that Africa is one of the most vulnerable continents to climate variability and change because of multiple stresses and low adaptive capacity. Some adaptation to current climate variability is taking place, however, this may be insufficient for future changes in climate.
(Working Group II Contribution to the IPCC, 4th Assessment Report, Climate Change Impacts, Adaptation and Vulnerability, Summary for Policy Makers.)