10. Human Impact on the Environment

1. Core content

Causes and consequences of the following (relate to conditions and circumstances in South Africa):

• The atmosphere and climate change

- carbon dioxide emissions;

- concept of ‘carbon footprint’ and the need to reduce the carbon footprint;

- deforestation;

- greenhouse effect and global warming: desertification, drought and floods;

- methane emissions;

- ozone depletion.

• Water

• Availability:

- Construction of dams

- Destruction of wetlands

- Poor farming practices

- Droughts and floods

- Exotic plantations and depletion of water table

- Boreholes and effects on aquifers

- Wastage

- Cost of water

• Quality:

- Water for domestic use, industry, agriculture and mining: pollution, diseases, eutrophication and algal bloom.

- The effect of mining on quality of water

- Thermal pollution

- The need for water purification and recycling

- Alien plants, e.g., Eichornia

• Food Security (link with population ecology dynamics)

- human exponential population growth;

- droughts and floods (climate change);

- poor farming practices: monoculture; pest control, loss of topsoil and the need for fertilisers;

- alien plants and reduction of agricultural land;

- the loss of wild varieties: impact on gene pools;

- genetically engineered foods;

- wastage.

• Loss of Biodiversity (the sixth extinction)

- habitat destruction: farming methods, e.g., overgrazing and monoculture, golf estates, mining, urbanisation, deforestation; loss of wetlands and grasslands;

- poaching, e.g., for rhino horn, ivory and ‘bush meat’;

- alien plant invasions: control using mechanical, chemical and biological methods; and

- indigenous knowledge systems and the sustainable use of the environment e.g., devils’ claw, rooibos, fynbos, the African potato (Hypoxis) and Hoodia.

• Solid Waste Disposal

- managing dumpsites for rehabilitation and prevention of soil and water pollution;

- the need for recycling;

- using methane from dumpsites for domestic use: heating and lighting; and

- safe disposal of nuclear waste.