THE DOOM AND GLOOM SCENARIOS FOR SOUTHERN AFRICA
Many General Circulation Models (GCMs) have been applied at centres all over the world to come up with future scenarios of how our climate might change and what the consequences of these changes might be. For Southern Africa a two to three degree Celsius rise of the mean annual temperature within the next 50 years is widely predicted and seems undisputed.
Precipitation is said to increase in the summer rainfall areas, but this incorporates more flooding events as more frequent heavy rains are predicted. The Western Cape’s winter rainfall region is said to become drier. Although different models come up with different scenarios, all scenarios predict more dynamic and variable conditions and that inevitably means more extreme events, if I understand it correctly.
How will these changes impact our biodiversity and ecosystems? Rutherford et al. (in DEAT 2000) based their predictions on a Hadley Centre model (HADCM2) and came up with shocking figures of an area reduction of 50% for all South African Biomes put together. According to this scenario the western, central and northern parts of the country would be most affected and could mean a total displacement of the Succulent Karoo Biome. The altered conditions might also suite invasive alien species that could rapidly expand their range (Dukes and Mooney 1999). Erasmus et al. (2002) did a study on animal taxa and came up with a substantial reduction in range in almost 80% of the 179 animal taxa included in their study.
The impacts on agriculture, rangelands and forestry depend on which scenario was used. Agriculture could be affected with losses up to 20% (Turpie et al 2002, du Toit et al. in DEAT 2000). This is a lot lower than expected if compared to the overall decline in habitat. This is due to the uncertainty of how much crops might benefit from carbon dioxide fertilization effect. Rangelands in the form of savanna grasslands might improve in the east with a positive effect on larger livestock farming areas, but in the west where sheep farming is dominant, the effect could be a substantial degradation in grazing land (Turpie et al 2002). Thomas et al. (2005) also explore the effects of climate change on the Kalahari dune system. They suggest a widespread remobilization of these sand dunes throughout the year that would have dire consequences for stock farming in the area.
According to the most recent downscaled scenarios (downscaled from General Circulation Models to Regional Climate Models) by Hewitson and Crane (2005) forestry in South Africa might be positively affected in the east as the east might become wetter and along with the carbon dioxide fertilization effect might be more favourable for forestry.
Water resources are to become scarcer as the west and central interior becomes drier. Arnell (1999) used Hadley Centre models (HADCM2 and HADCM3) to predict a reduction in runoff of up to 30% for the Limpopo basin, but only a 5% reduction for the Orange river basin (due to predicted increase in rainfall in the Drakensberg?). South Africa also has an increasing demand for potable water and this combined with the supply becoming scarcer will result in the inability to meet these demands, especially in the Western Cape, where strong population growth is adding to the conundrum (New 2002). Mukheiber and Sparks (2003) add more gloom to the picture by adding that the water quality could also reduce “unless there are significant shifts in policy vision” (Meadows 2006 p.142).
The cherry on the top of this doom and gloom cake is the influence future climate change might have on health. Van Lieshout et al. (2004) used four emission scenarios from the Intergovernmental Panel on Climate Change’s (IPPC) Third Assessment Report (2001) to predict a likely increase in malaria in sub-Saharan Africa. Although the affects of HIV/AIDS have not been assessed in the light of climate change, the overall decline in food security and water supply predicted will inadvertently affect vulnerable populations (Meadows 2006).
If this will turn out to be alarmist or true will unfold itself within the next 50 years… a scary thought for me as I will probably be around to witness it!
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Cavazos T and Hewitson BC. 2005. Performance of NCEP-NCAR reanalysis variables in statistical downscaling of daily precipitation. Climate Research 28: 95–107.
DEAT (Department of Environment Affairs and Tourism). 2000. South African Country Study on Climate Change. DEAT, Pretoria.
Dukes JS and Mooney HA. 1999. Does global change increase the success of biological invaders? Trends in Ecology and Evolution 14: 135–139.
Erasmus BFN, van Jaarsveld AS, Chown SL, Kshatriya M and Wessels KJ. 2002. Vulnerability of South African animal taxa to climate change. Global Change Biology 8: 679–693.
Hewitson B and Crane RG. 2005. Consensus Between GCM Climate Change Projections with Empirical Downscaling. Unpublished report, South African Water Research Commission Project 1430; Assessments of Impacts and Adaptation to Climate Change in Multiple Regions and Sectors (AIACC) Project AF07, and EPA Cooperative Agreement Number R-830533-01-0.
Hulme M. (ed.). 1996. Climatic Change and Southern Africa. Climate Research Unit, University of East Anglia, Norwich, U.K.
IPCC (Intergovernmental Panel on Climate Change). 2001: Climate Change 2001: The Scientific Basis. Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate Change [J.T. Houghton, Y. Ding, D.J. Griggs, M. Noguer, P.J. van der Linden, X. Dai, K. Maskell, and C.A. Johnson (eds)]. Cambridge University Press, Cambridge, U.K.
Meadows ME. 2006. Global Change and Southern Africa. Geographical Research 44(2): 135-145.
Meadows ME and Hoffman MT. 2003. Land degradation and climate change in South Africa. Geographical Journal 169: 168–177.
Mukheiber P and Sparks D. 2003. Water Resource Management and Climate Change in South Africa: Visions, Driving Factors and Sustainable Development Indicators. Report of Phase I of the Sustainable Development and Climate Change Project, Energy and Development Research Centre, University of Cape Town, South Africa.
New M. 2002. Climate change and water resources in the southwestern Cape, South Africa. South African Journal of Science 98: 369–376.
Thomas DSG, Knight M and Wiggs GFS. 2005. Remobilization of southern African desert dune systems by twenty-first century global warming. Nature 435: 1218–1222.
Turpie J, Winkler H, Spalding-Flecher R and Midgley G. 2002. Economic Impacts of Climate Change in South Africa: a Preliminary Analysis of Unmitigated Damage Costs. Southern Waters Ecological Research and Consulting and Energy Development Research Centre, University of Cape Town, South Africa.
van Lieshout M, Kovats RS, Livermore MTJ. And Martens P. 2004: Climate change and malaria: analysis of the SRES climate and socio-economic scenarios. Global Environmental Change 14: 87–99.
BCB Hons NISL student
University of the Western Cape
Private Bag X17
1.I know that plagiarism is wrong. Plagiarism is to use another’s work and to pretend that it is one’s own.
2. I have used the CSE/CBE convention for citation and referencing. Each significant contribution to, and quotation in this project from the work, or works, of other people has been attributed, and has been cited and referenced.
3. This assignment is my own work.
4. I have not allowed, and will not allow anyone to copy my work with the intention of passing it off as his or her own work.