27 October 2021
Climate impacts in southern Africa during the 21st Century
Report for Earthjustice and the Centre for Environmental Rights
by Robert Scholes and Francois Engelbrecht
Global Change Institute, University of the Witwatersrand
- There is no scientific doubt that the climate of southern Africa is becoming warmer, the atmospheric concentration of greenhouse gases is increasing and the sea level surrounding the continent is rising. Human activities are by far the largest cause of these changes. The principle causes are the global burning of fossil fuels and the transformation of the global land surface from natural vegetation to croplands, pastures and human settlements.
- The climate will continue to change throughout the 21st century, to a degree mostly determined by human actions and the policies that guide them. Global ‘low mitigation futures’ that lead to global mean warming well in excess of 3 °C pose much higher risks to the future development of South Africa than ‘high mitigation futures’ which limit warming below 2 °C; which in turn have higher risks than futures which stay below 1.5 °C, or only briefly exceed it. The latter two futures require urgent and strenuous efforts to reduce greenhouse gas emissions, including by developing countries like South Africa.
- Southern Africa is particularly vulnerable to climate change because of its geographical location and socioeconomic development state. It is an already warm and dry region, projected to become warmer and drier, and has many demands on its institutions and finances in addition to climate change. Warming in the interior of southern Africa is occurring at about twice the global average rate.
- There is a high likelihood that agricultural production in southern Africa, including staple crops and livestock, will be reduced relative to the no climate change case. This is because the region is already beyond the temperature optimum for most crop and livestock production, and crop and forage production in an already dry country decreases if soil moisture decreases further. These impacts increase as the level of global warming increases, and at 3 °C of global warming the collapse of key crops and the livestock sector are likely.
- Freshwater availability, already critically limited in southern Africa, will be reduced in future as a result of decreasing rainfall and increasing evaporation. These impacts will amplify as the level of global warming increases. Water quality also decreases in a warmer, drier southern Africa, increasing the risk of water-borne diseases.
- The likelihood of long-duration droughts increases in the future because of two fundamental mechanisms resulting from global warming: the strengthening of subsidence over southern Africa, and the poleward movement of frontal systems. When droughts exceed the historically-experienced frequency and intensity, the coping mechanisms are overwhelmed. These risks increase from 1.5 to 2 °C of global warming, with further increases under higher levels of global warming.
- The number, intensity and duration of heat waves in South Africa will increase steeply in future as a result of global warming. The capacity to perform manual labour out of doors decreases dramatically as the occurrence of heat waves increases. Human mortality increases, particularly in urban areas with inadequate housing, but may in some locations be offset by decreases in mortality as a result of fewer cold spells.
- The risk of severe storms, including intense tropical cyclones and very intense thunderstorms, increases with climate change in southern Africa. As a result, loss of life, injury and damage to infrastructure also increases.
- Thousands of species, many occurring only in southern Africa, are at increased risk of premature extinction as a result of human-caused climate change. This loss has negative consequences for human wellbeing and the economy, as well as weakening the capacity to adapt to climate change.