Overview of chapter
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South Africa is sensitive to climate change, and contributed
about 1.2% to global warming in 1990.
The levels of sulphur dioxide, nitric oxide and ozone are on
average within the accepted South African guidelines for human
health and the prevention of direct ecosystem damage. The
measured concentrations at ground level are not currently showing an upward
trend.
There are occasions, especially in the major urban areas,
where the concentrations of sulphur dioxide, nitric oxide, ozone and
smoke particles could lead to further health problems in people
who are already experiencing respiratory problems. No trend in the
number of times which these levels are exceeded is apparent, but
with more people living in urban areas, the impact is likely to
increase.
Indoor air quality constitutes a health hazard in
poorly-ventilated dwellings without chimneys, where coal, wood,
paraffin or dung are used as fuel. The electrification
of houses will imprive this situation, as will the general
improvement in housing design and construction brought about by the
national housing policy. Greater efforts to improve the ambient air
quality (for instance by paving of roads in informal settlements),
to promote low-smoke fuels and to educate the public on the dangers
of open fires inside houses, are necessary.
Susceptible terrestrial and freshwater ecosystems are likely to show
adverse effects of acid deposition in a few decades if the current
emission rates of sulphur dioxide and nitric oxide are continued or
increased.
Authors: Scholes Dr R J, van der Merwe M, CSIR Division of Water, Environment & Forestry Technology and John J, Oosthuizen R, CSIR
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South Africa is a climatically sensitive country. Most crop agriculture in South Africa takes place where it is only just climatically suitable, particularly with respect to rainfall. Water is the resource most limiting to national development. Its availability now and in the future is closely linked to rainfall, temperature, management and land use practices.
For more background information about climate and atmospheric change read this section.
The direct causes of atmospheric change and
the enhanced greenhouse effect, are human activities such as the
burning of fossil fuels and the clearing of natural vegetation
for agricultural purposes.
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| A veldfire |
These activities emit a variety of gases,
the most important of which are carbon dioxide, methane and nitrous
oxide (which contribute to global warming); nitric oxide and
volatile organic compounds; sulphur dioxide and dust and smoke particles. Sulphur dioxide and nitric oxide together are deposited as acids, which are corrosive to buildings and harmful to ecosystems as certain plant and animal species are very sensitive to changes in soil and water acidity. Acidification of surface water also makes it less suitable for drinking, irrigation, and industrial uses. Certain gases, such as the ozone-depleting chlorofluorocarbons (CFC's), find their way to the upper atmosphere, where they destroy ozone, the chemical which blocks harmful ultra-violet radiation.
For more information about the drivers of atmospheric change, read this section.
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The energy sector, which includes electricity generation,
emissions resulting from oil and coal refining to produce petroleum
products, coal mining and gas extraction, wood burning and the
burning of coal and oil to produce heat for industrial and other
purposes, is the single largest source of carbon dioxide (CO2) and sulphur dioxide
(SO2) emissions in South Africa. This is mainly
due to the reliance on coal and oil or its products for the
country's energy purposes .
Emissions from vehicles (aeroplanes, ships, trains
and road vehicles), contribute 44% of the total national nitric
oxide emissions and 45% of the total national volatile organic
carbon emissions (VOC). Volatile organic
carbon emissions (VOC) combines
with nitric oxide and carbon monoxide, in the presence of sunlight,
to form photochemical smog, which contains gases which are toxic to plants and animals. This is particularly a
problem in urban areas.
Agricultural activities contribute the most to methane emissions (48% of
the national total) and nitrous oxide emissions (78% of the national total).
For more information about the above pressures read this section.
Concentrations of carbon
dioxide as measured at Cape Point show an overall increase of
approximately 0.6% per year. This is a global phenomenon which is
the subject of much concern and research.
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| Carbon dioxide is measured at Cape Point |
Lower atmosphere (Tropospheric) methane has increased
steadily from 1983 to 1998 (total increase of 8.3% over the time
period).
For almost half the year, minimum amount of erythema dose (MED) levels fall within the
dangerous to very dangerous categories for Cape Town. Durban and Pretoria.
January and December show the highest levels.
In general, the worst air quality in South
Africa occurs when wood, dung or coal is used as fuel inside
poorly-ventilated dwellings, in informal settlements and rural
villages, adversely affecting human health.
There has been a decrease
in ambient lead concentrations over the past few years which can be
attributed to the decrease in lead concentrations in petrol to 10
g/d in 1991).
On average, the temperature stations in South
Africa showed an increase of 0.2° C during the 1990s, which is
not yet a cause for alarm. The increase in temperature may be associated with
global warming, although it is hard to prove statistically with such
a short record.
This is where you can find more information about the state
of climatic and atmospheric change in South Africa.
Warmer temperatures in South
Africa may lead to:
- Changes in biogeographic distributions and loss of biodiversity.
- More human deaths, especially among the elderly, due directly to heat waves.
- Greater risk of epidemic infectious illnesses, such as malaria (due to an expansion of suitable habitat for mosquitoes which transmit malaria).
Malaria epidemics have been
linked to both temperature and rainfall in South Africa, and appear
to show a steady increase overall since 1993.
Increased ozone levels in the lower atmosphere (resulting from NOx and hydrocarbons reacting in the sunlight) will lead to
respiratory health effects.
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| Graphic of the ozone hole over Antarctica. |
Depletion of upper atmosphere stratospheric ozone will
result in more of the harmful ultra-violet B radiation
reaching ground level. This would lead to increases in skin cancer
and cataracts, and possibly reduction in the effectiveness of the
immune system.
Some of the highest pollution concentrations are found
in rural, indoor environments. The impact (sickness and mortality due to
air pollution) in South Africa has not been quantified.
It is especially a problem for children of low-income
families, who live mainly in rural areas and in inadequate housing.
Depletion of upper atmosphere stratosphericozone will
result in more of the harmful ultra-violet B radiation
reaching ground level. Ultra-violet B radiation radiation causes damage to the
photosynthetic pathways and genetic structure of plants.
Read this section for more information about the impacts of climatic and atmospheric change.
A massive electrification programme aims at replacing the use of coal
and wood as a domestic energy source, and thus improving indoor air
quality in rural areas and informal settlements. Nearly 1
million households have been electrified since 1994, but coal and
wood remain important fuel sources for reasons including customary
domestic activities.
In 1990, South Africa became a signatory to the Montreal
Protocol, the purpose of which is to limit the emissions of
substances harmful to the ozone layer. This Protocol has been highly
successful.
Since South Africa is a climatically-sensitive country, the issue
of climate variability and potential climate change is taken
seriously at the national level. An interdepartmental committee on
climate change commissioned reviews on the subject. South Africa signed the United Nations Framework
Convention on Climate Change (UNFCCC) in 1994, and ratified it in
1997.
For more information about South Africa's responses to climatic and atmospheric changes click here.
For more information about the outcomes of climatic and atmospheric change, click here.
Climatic and atmospheric change has some linkages with other environmental issues in South Africa.
Click here to find out where these linkages are
Reporting on the state of the environment requires access to accurate, up to date information.
To find out more about data issues with regard to climatic and atmospheric change, click here.
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There is also information about Climatic and Atmospheric Change in the following reports:
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Metropolitan reports:
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Copyright © 1999 Department of Environmental
Affairs and Tourism. All Rights Reserved.
Site maintained by the Directorate Environmental Information and Reporting
Last update: October 1999
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