The atmosphere is a shared resource that is linked in many ways to ecosystems and human development. Its variable and unpredictable nature in South Africa directly affects food production, human health, and biodiversity. Consequently, the main issues of concern are:
- Indoor and ambient air pollution and the associated health impacts
- Climate change and variability and its implications for ecosystems and human well-being
- The depletion of stratospheric ozone.
The quality of air depends on the quantities of natural and human-caused emissions and the potential of the atmosphere and ecosystems to absorb and remove pollutants. Air pollutants vary in terms of how long they remain in the atmosphere and the impacts they cause. Gases such as carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O, also known as ‘laughing gas’) and chlorofluorocarbons (CFCs) are long-lived and internationally important because of their implications for global warming and stratospheric ozone depletion. Pollutants such as nitrogen dioxide (NO2), sulphur dioxide (SO2), carbon monoxide (CO), and particulate matter (PM) are important locally in terms of human and ecological health.
South Africa is a water-stressed country with a well-developed agricultural sector, and it is sensitive to the effects of climate change – now recognized as a pressing environmental issue. These effects could lead to floods, droughts, rising sea levels, extreme weather events, increased tropical diseases, water scarcity, famines, decline in agricultural productivity, and shifts in migration and trade patterns.
Although stratospheric ozone depletion is a global concern, the impacts are also important locally. They include increased harmful ultraviolet-B (UV-B) radiation reaching ground level, with associated increases in skin cancer, cataract and immune system-related health risks. UV-B radiation also affects vegetation by damaging the photosynthetic pathways and genetic structure of plants.