In the household sector, fuelwood accounts for 97% of all energy consumed (Chidumayo, 1997). Although natural stocks of wood may be high, wood resources available to the majority of the rural population are very low in many areas. Brickmaking and tobacco and tea curing are major wood uses. In Zimbabwe, wood used for brickmaking is said to equal that used for cooking in rural areas (Bradley and Dewees, 1993); tobacco estates in Malawi account for 21% of total fuelwood consumption (Moyo et al., 1993). In Botswana, the fencing of fields to keep out livestock consumes 1.5 times more wood than is used for cooking in farming households (Tietema et al., 1991). Indigenous miombo and other woodlands in sub-Saharan Africa contribute significantly to the firewood harvested for consumption and conversion to charcoal. Stands are left to recover, with minimal active management. The ability of users to purchase alternative forms of energy (gas or electricity), as well as charcoal, depends on the economics of each family. Therefore, poor people (with limited buying power) are most vulnerable to reductions in fuelwood supply. Increasing populations also are contributing to depletion of resources. In relatively dense woodland areas, where population density is low, there usually is enough deadwood that can be collected and used for fuelwood. Increasing incidence of drought, however, leads to increased fire frequency-which, in turn, reduces deadwood material in woodlands. If current natural resource management systems are not changed, Africa could run the risk of depleting its forest resources used as biomass energy at a rate faster than the rate of population growth. The paucity of data on biomass depletion and regeneration rates makes meaningful assessment difficult and compounds the problems of possible reduced precipitation and subsequent lower regeneration rates by making it difficult to identify appropriate response options. There already are indications of a negative supply balance (e.g., extensive household utilization of agricultural and animal wastes for energy).
In 1992, Africa's electricity output was 312,000 GWh; thermal power provided 78% and hydroelectricity 19%, with a small amount (3%) from nuclear sources in South Africa (ADB AEP, 1996). Thermal power plants require huge volumes of water in their cooling systems; in a situation of reduced rainfall, loss of cooling-water resources will not only reduce generation capacity but also retard construction of new plants. It may be reasonably expected, therefore, that exploitation of the continent's massive coal reserves in areas with such resources would be inhibited by both the anti-coal lobby and shortages of cooling water. In the past (e.g., during the drought of 1991-92), declines in precipitation led to a significant loss of total hydropower energy, including losses of as much as 30% from the Kariba Dam (which supplies power for Zambia and Zimbabwe). It has been suggested that future hydropwer output could could be affected by climate change. Salewicz (1995) investigated the vulnerability of the Zambezi basin to climate change. He noted that 75% of the lower Zambezi waters flow into Kariba. Under climate change scenarios, this area is projected to experience increased rainfall and runoff into Lake Kariba. Although there may be shifts in the seasonal reliability of given discharges for the Lower Zambezi, it is possible that hydropower generation capacity would be adversely affected. Similar impacts could occur on the Congo, Nile, and Niger river hydropower systems, resulting in critical electricity supply shortfalls throughout the continent. In addition, the continent's massive hydroelectric potential of 150,000 GWh/yr would be significantly curtailed. Such a situation would lead to the introduction of major changes in fuel supply strategies in most countries. A case has been made for developing micro- and small-scale hydropower plants in Africa to overcome the cost of large-scale generation systems. This type of plant will require a defined minimum level of runoff. Reductions in precipitation could significantly reduce the number of viable sites for such micro-hydro installations.
Changes in future climate should be actively considered in developing a sustainable industrial development path for Africa. Vulnerability in African industry may relate more to the inhibiting effects of climate change on industrial expansion than to its effects on existing industrial installations and investments. The most serious impacts of climate change on this sector would be related to loss of competitiveness associated with increased costs of production resulting from changes or retrofitting of plants for cleaner production. Reduced surface-water supplies would lead to extended use of groundwater sources-which, in most cases, have to be treated on site to achieve desired water-quality standards for specific industrial applications. Other major effects will result from a lack of water for industrial processes and increased costs of cooling for temperature-controlled processes and storage; Africa's industry has a large number of agro-industrial operations that need large amounts of water.
Besides these direct effects, there will be indirect effects, such as rising water costs; in cases of severe and recurrent water shortages, this factor could lead to relocation of industrial plants. Electricity shortages, due to a drop in the water level which causes a decline in hydropower, also will affect industry-particularly the steel sector (including iron and steel), ferro-chrome production, cement production, textiles, and aluminum production. These industries are among some of the most advanced on the continent, but they are highly dependent on constant electricity supplies. Although there are no data to indicate the level of water shortages that may result from a decline in precipitation, it is obvious that water shortages that affect concentrated urban settlements also will have a debilitating effect on industrial production. Water demand in many states in southern and northern Africa already has exceeded or is expected to exceed water supply soon.
Although detailed assessments of the impact of sea-level rise on coastal industries have been made for Asia and other regions, little information is available for Africa. It can be assumed, however, that most of the impacts that would ensue in other coastal zones would apply equally in Africa. Most impacts would be related to relocation of industries. The extent of these impacts could not be assessed in any detail without a more complete assessment of coastal zone industrial locations.
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