The warning of the earth is believed to result from human activities, primarily the burning of fossil fuels (such as soil, coal and petroleum), along with the use of agricultural and industrial chemicals. This results in global concetrations of atmospheric trace gases, collectively known as greenhouse gases, which contribute to change of earth’s climate.

Some gases in the earth’s atmosphere are called greenhouse gases because they function in much the same way as horticultural greenhouses. These gases – carbon dioxide, methane, nitrous oxide, ozone and chloroflourocarbons (CFCs) trap some of the heat from the sun’s radiation.

As sunlight heats up the sea and land, the warned surface of the earth radiates the heat back towards space. On its way, some of the heat is absorbed by the gases, raising air temperatures and leading to greater concetration of atmospheric water vapour – an efficient absorber o heat. This phenomenon is known as the greenhouse effect.

Carbon emissions per person per year in the Southern African Development Community (SADC) region are less than one tonne compared to the global average of 1.2 tonnes.

Contribution of SADC to total global emissions is less than two percent for all greenhouse gases. However, South Africa emits more greenhouse gases than the rest of Southern Africa combined.

Greenhouse gas Required percentage

Reduction in emissions

Carbon dioxide 60

Methane 5-20

Nitrous oxide 70-80

CFC-11 70-75

Source: IPCC Working Group 1 Report, June 1990.

Prediction of impacts resulting from climate change is very difficult and complex because it depends on specific regional conditions which, over the next generation, are also subject to enormous change. Small changes in climate in southern Africa can seriously affect the balance between supply and demand of water resources, food production and energy resources.

Scientists predict that if current trends continue, the combined effect of greenhouse gases will raise global mean temperature by between 0.3C per decade. This means that by 2025 the global mean temperature would have gone up 1C.

Agriculture is likely to be affected in various ways. It is possible that the consequence might even be beneficial in some regions, for example, where land presently is not available for agriculture, but with increased temperature and rainfall, could support certain crops.

However, other regions can become less suitable for agriculture if droughts are more frequent or if rainfall patterns change significantly. Higher rainfall can lead to greater soil erosion and nutrient-leaching.

Plants will grow faster due to the carbon dioxide-rich environment as they absorb more carbon dioxide through photosythesis. The life cycles of most plant will probably accelerate, resulting in poorer soils as increasing amounts of minerals are taken up from the soil and used by the plants.

Climate change would affect the biological diversity of fauna and flora by altering their geographical distribution and even threatening their survival if the change is too severe or too rapid. This could lead to the disappearance of many rare species (plant and animal), such as the lechwe, rhino, and some orchids.

Plant species tolerant to increased carbon dioxide level or to warmer temperatures, would tend to predominate over other species. This, in turn, would lead to a change in distribution of the animal population that feed on them. National parks in the SADC region may become less spectacular and biodiverse with the disappearance of the large mammal species.

There would be significant shifts in most large ecological zones and up to 20 percent of the region would be affected, especially grassland and savanna ecozones. An ecozone shift could significantly threaten those ecosystems the reserves were established to protect.

According to scientific predictions, climate change would cause a 65 centimetres (cm) rise in sea level by the year 2100, most of that due to melting glaciers and expansion of the ocean water as it warms up.

THE OKAVANGO DELTA

The Okavango Delta, located in northern Botswana, is an extensive area of wetland, rich in wildlife. According to some models, it is suggested that by 2050s, rainfall in the area would decline by about five percent, and become more variable from year to year. Temperatures could increase by about 1.5C and potential evaporation by 15 percent. Runoff in the Okavango catchment would decrease by 20 percent, but there would be little change in the savanna vegetation of the area. The delta region would become a more attractive habitat for ticks and mosquitoes, but less attractive for tsetse.

More giraffes, warthogs and kudus would concetrate in the area together with a range of predators which already inhabit the area. Declines in rainfall and inflow to the delta may cause severe difficulties for elephants, 50,000 of them currently inhabit this area.

Species such as springbok, gemsbok and dik-dik may also find the area less attractive. Increases in mosquitoes, changes in wildlife species and higher temperatures would all act to reduce tourism potential in this unique wetland.

Source: Hulme, M., Climate Change and Southern Africa – An Exploration of some Potential Impacts and Implications in the SADC Region, WWF/ Univeristy of East Anglia, Climate Research Unit, Gland/Norwick, 1996,pp.73-74

The result would be inundated wetlands and lowlands, eroded shorelines and increased coastal flooding.

Socio-economic impacts of sea-level for the SADC region would include the uprooting of human settlements and loss of some coastal fisheries and tourism resorts. Mozambique is one of the five African countries which would be vulnerable, affecting its growing tourism industry.

Along the SADC eastern and southwestern coasts, coral reefs could be damaged or killed by the increase in sea temperatures. The consequences could vast, as coral reefs shelter many specie of fish and other sea organisms, and protect the coast.

Rising temperatures would increase evaporation rates. With the expected decrease of annual rainfall in the SADC region, water availability would be reduced, affecting river flows and regional water resources. Runoff would increase in wetter regions, and droughts would become more frequent.

If belts of warm weather move further south as predicted, the cold fronts which normally sweep up from the southern ocean bringing winter rain to the Cape area might increasingly miss the southern tip of Africa. The area could change its winter rainfall pattern to summer. The agricultural crops would have to change, leading to some local implications for the economy.

Climate change is a threat to the security and well-being of the SADC region. It could result in increasing number of environmental refugees (people displaced by degradation of land, flooding or drought, or any other environmental phenomenon). For example, people would be moving inland from coastal regions if sea level rises.

People can also start moving from drier areas to more productive ones, putting even more pressure on the available natural resources. Increased rates of localised deforestation due to such settlements would further increase atmospheric carbon dioxide emissions.

African nations in general and SADC countries in particular would be vulnerable to the changes caused by climate change, due to their limited financial and technological capabilities to adapt to these changes. Therefore, there is need to start looking at alternative strategies to mitigate the effects of climate change

In Namibia, some commercial ranchers are already specialising in small stock which can adapt better and faster to the impact of climate change, i.e. less water and higher temperatures.

Environmental policy should focus on options to reduce carbon dioxide emissions, such as energy efficiency and conservation, particularly with regard to fossil fuels. Policy re-assessments in favour of small stock and wildlife need to be introduced.

Greater use of alternative non-fossil energy sources, including modern and sustainable use of biomass; replacing coal with natural gas and others; the recovery of carbon dioxide via reforestation, are some alternatives to curb the warming of the globe.

The role of biotechnology in manipulating the various genetic combinations of plant species would help create drought tolerant species.

The SADC Plant Genetic Resource Centre (SPGRC) is already looking into this aspect.

FRAMEWORK CONVENTION ON CLIMATE CHANGE (FCCC)

Most southern African countries signed and ratifies the United Nations Framework Convention on Climate Change.

However, African countries are not obliged under the convention to reduce their emissions of greenhouse gases to a specific target and deadline.

The industrialised countries (which contribute 98 percent of the global emissions) are required to reduce their emissions by the year 2000 to 1990 levels.

Considering biotic and energy sources, the African share of future carbon dioxide emissions is projected to be between 12-16 percent of the global total by 2100.

Achieving an effective reduction in the emissions of heat-trapping gases would require a major reduction in the use of fossil fuels globally, cessation of deforestation and a substantial effort in reforestation. Africa alone is estimated to contribute to deforestation at the rate of 3.6 million hectares per year.

The development and use of environmentally benign sources of energy such as solar, wind and hydro will help lessen carbon dioxide emissions. However, the economic costs of switching over to these alternative energy sources are very high and probably not affordable to southern Africa.

Disaster preparedness would probably become critical in preventing or limiting the impacts of extreme climatic events, especially impacts on the more vulnerable social groups.