Chapter 2: State and Trends
Figure 2.1.1: Direct black carbon radiation from residential kerosene lighting (W/m2
)
some hydrofluorocarbons (HFCs), have a warming effect on the climate. SLCPs are responsible for a substantial fraction of the climate change experienced to date and will have a significant influence on the rate of warming in the near- term (the next few decades). Temperatures over the interior regions of subtropical southern and northern Africa have been increasing at a rate of about 2°C per century over the past five decades, about twice the global rate of temperature increase (Jones et al. 2012, Engelbrecht et al. 2015).
Source: Lam et al. 2012
Outdoor air pollution Growth in urbanization, industrialization and motorization has increased pollution in Africa. Emission of air pollutants, their trans-boundary transport and dispersion, and eventual deposition, contribute substantially to pollution levels around the continent and beyond. The Sahara and its surroundings produce half of the global yearly mineral dust, and is the main source of atmospheric mineral dust of the world. Volcanic eruptions also contribute to this air pollution (Muthama et. al. 2012), and Africa has a few active volcanoes including Mount Nyamulagira.
Climate change resulting from human activities is manifesting notable impacts on the continent. Short-lived climate pollutants (SLCPs), substances with a relatively short lifetime in the atmosphere, from a few days to a couple of decades, including black carbon, methane, tropospheric ozone, and
Ambient air pollution, in either gaseous or particulate forms, negatively impacts economies and livelihoods in Africa. Major sources of outdoor air pollution in the region include motor vehicles, industrial processes, power generation, and household combustion of solid fuel (Muthama et. al. 2015). The air pollution sources across the continent are mainly in industrial areas, urban centres and motorized highways.
Monitoring of surface ozone over southern Africa has shown that ambient concentrations often exceed a threshold of 40 parts per billion (ppb) at which they can damage vegetation (Kirkman et al. 2000). There are large areas in the region where surface ozone concentration exceeds 40 ppb for up to 10 hours per day, while others have exceeded 80 ppb, particularly in the winter when mean ozone concentrations are higher. The areas where the 40 ppb threshold is exceeded coincide with maize growing areas in South Africa and Zimbabwe (Kirkman et al. 2000), and this may negatively impact crop yields.
The scarcity of information about air quality relating to the African continent is a reality illustrated by the recent map of exposure to particulate matter (PM10
) in urban areas
worldwide (WHO 2012). Of 1 100 urban areas listed, only ten (less than one per cent) are on the African continent, and this is six times less than the station data available in France (Figure 2.1.2).
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