Climate Change - South Africa

What causes climate change?
The global climate system is driven by energy from the sun. Several gases in the atmosphere act to trap the energy from the sun, thus warming the earth. These gases are called greenhouse gases and the process is the greenhouse effect. Without this there would be no life on earth. Human activities over the last 200 years, particularly the burning of fossil fuels (oil, coal, natural gas) and the clearing of forests, have increased the concentration of greenhouse gases in the atmosphere. This is likely to lead to more solar radiation being trapped, which in turn will lead to the earth's surface warming up - called the enhanced greenhouse effect.

How does a changing climate influence South Africa?
Higher temperatures will influence the rainfall, but it is still uncertain how the annual rainfall will change. It could increase in some parts of the country, and decrease in other parts.
Water resources: South Africa's industrial, domestic and agricultural users are highly dependent on a reliable supply of water. A reduction in rainfall amount or variability, or an increase in evaporation (due to higher temperatures) would further strain the already limited amount of water resources. An increase in rainfall, or a reduction in plant water use (due to a higher atmospheric concentration of carbon dioxide) would ease the problem slightly.

Human and animal health: There are several important insect-carried diseases of humans and livestock which are sensitive to the climate. A small increase in temperature would allow, for instance, malaria to spread into areas which are currently malaria-free, and would increase its severity in areas where it already occurs.

Maize and wheat: It is currently estimated that a 10% increase in rainfall coupled with an increase in carbon dioxide would lead to a 10-20% increase in wheat and maize production, while a 10% decrease in rainfall would be approximately balanced by the rising carbon dioxide content of the atmosphere. Slightly warmer temperatures may lead to a small reduction in wheat yields, but would have little effect on maize. These predictions are not very certain.

Grazing livestock: Most of South Africa, especially the drier part, is used for grazing by cattle, sheep and wildlife. Higher carbon dioxide will lead to less protein in the grass, which will reduce any benefit resulting from increased plant growth. Less rainfall would lead to proportionately less animal production.

Forestry: The forestry industry could probably tolerate a small increase in temperature, but a decrease in rainfall would reduce the area which can support plantations, and the growth rate of the trees. A positive point is that rising carbon dioxide could help reduce water use by plantations.

The coastal zone: If the warming of ocean water were to continue unabated, the polar icecaps will melt and the seal level will rise. This is anticipated in the next century. The consequences in South Africa of a small sea level rise are not very extensive because the coastline is relatively steep.

Fisheries: Changes in the oceans have important implications for South Africa. In the recent past, variation in ocean currents has caused major changes in several fish resources important to the country. Future variations, which may be linked to climate change, could have a similar effect.

Biodiversity: Plants, in particular, have trouble keeping up with rapid climate change. Small, isolated populations could go extinct as a result. South Africa has about 10% of all the plant species in the world, of which about half occur nowhere else on earth. Warming, and a change in the seasonal rainfall of the Cape floral kingdom, are issues of concern to conservationists.
What can we do to slow the process down?

The enhanced greenhouse effect can be slowed down by following two guidelines: (1) Increase sinks and (2) decrease sources of greenhouse gases. A sink is a process which removes greenhouse gases from the atmosphere. For example: growing a tree where one did not previously exist provides a sink for carbon dioxide, because the tree “extracts" carbon dioxide for photosynthesis. A source is a place or activity from which greenhouse gases are emitted. This can be a process such as coal burning or a location such as cultivated fields.