The main issues of concern regarding the atmosphere in Southern Africa are the occurrence of flooding and droughts arising from climate variability, impacts of climate change on vegetation systems, biodiversity, freshwater availability, food production and localized air quality problems associated with emissions from industry, vehicles and use of domestic fuels.
Maize rotting in the fields after the Feb/March 2000 floods in Mozambique
Pieternella Pieterse/Still Pictures
Rainfall in Southern Africa is strongly influenced by the Inter-Tropical Convergence Zone (ITCZ), a zone close to the equator where massive rain-bearing clouds form when the South East Trade Wind (from the south east of the continent) meets the North East Monsoon Winds. The ITCZ changes position during the year, oscillating between the Equator and the Tropic of Capricorn, and its southward movement usually marks the beginning of a rainy season. The further south the zone moves, the more promising this is considered to be for the rainy season. In a normal season, the ITCZ can exert an influence between mid- Tanzania and southern Zimbabwe and is associated with favourable rainfall. Another system, the Botswana High, often tends to push the ITCZ away, resulting in periods of drought.
The ENSO also influences Southern Africa's climate, tending to bring either heavy rains often accompanied by severe floods (as in 1999/2000 when Mozambique was exceptionally hard hit), or drought (as in 1982/83 when much of Southern Africa was severely affected) (National Drought Mitigation Center 2000).
In the wet season, normal rainfall in Southern Africa ranges from 50 mm to over 1000 mm. Recent weather patterns have, however, been erratic with severe droughts recorded in 1967–73, 1981–83, 1986/87, 1991/92 and 1993/4. Floods have also been observed, most notably across most of Southern Africa in 1999/2000 (Chenje & Johnson 1994, WMO 2000).
The drought of 1991/2 was the severest on record, causing a 54 per cent reduction in cereal harvest and exposing more than 17 million people to risk of starvation (Calliham, Eriksen and Herrick 1994). Zimbabwe alone imported an additional 800 000 tonnes of maize, 250 000 tonnes of wheat, and 200 000 tonnes of sugar (Makarau 1992). Water and electricity shortages resulted in a 9 per cent reduction in manufacturing output and a 6 per cent reduction in foreign exchange (Benson & Clay 1994).
Cyclone Eline, which hit south-eastern Africa in 1999/2000, affected 150 000 families and wreaked havoc in Mozambique where it caused US$273 million worth of physical damage, and cost US$295 million in lost production, and US$31 million in food imports (Mozambique National News Agency 2000).
A combination of dry spells, severe floods, and disruption of farming activities between 1999 and 2001 has left Southern Africa with meagre food reserves. Several of the sub-region's countries have faced food shortages (FAO 2001a).
The Southern African Development Community (SADC) has developed a Sub-Regional Action Programme to Combat Desertification in southern Africa, in line with the UNCCD. All of the countries in the Southern African sub-region are party to the UNCCD, and Lesotho, Malawi, Swaziland, Tanzania, and Zimbabwe have also produced National Action Plans (UNCCD 2001).
Early warning and response strategies for mitigating the impacts of climate variability are relatively well developed in the sub-region (see Box 2a.4) and a drought fund is in place to mitigate the effects of poor rainfall (Chimhete 1997). However, monitoring, research, and preparedness strategies need further strengthening. This is evidenced by the response to cyclone Eline—according to some sources, the early warning systems did not supply sufficient information about the extent of the impacts of the cyclone, resulting in the loss of many lives that could have been saved (CNN 2000).
|Box 2a.4 Early warning in Southern Africa|
|Source:Masundire, 1993. Photo: UNEP|