NCCIS
National Climate Change Information System
Climate Change Projections
Overview
A key feature of the projected climate change futures of South Africa is that temperatures are to increase drastically under low mitigation scenarios. For the far-future period of 2080-2099, temperature increases of more than 4 °C are likely over the entire South African interior, with increases of more than 6 °C plausible over large parts of the western, central and northern parts. Such increases will also be associated with drastic increases in the numbers of heat-wave days and very hot days, with potentially devastating impacts on agriculture, water security, biodiversity and human health. The model projections are indicative that a modest-high mitigation pathway can still significantly decrease the amplitude of this warming – most projections suggest that under Representative Concentration Pathway 4.5(RCP4.5), for example, temperature increases over the interior can be constrained to 2.5 to 4 °C. Nevertheless, it should be realised that South Africa is plausibly committed to relatively large (compared to the global average) increases in near-surface temperatures, even under high-mitigation futures.
Key Messages
South Africa is expected to experience:
Increase in mean, maximum and minimum temperatures.
Increase in very hot days – above 35 °C and the frequency of heat wave events.
Drier conditions in the future, with regional variation.
Slight increases in rainfall towards the north-eastern region.
A strong drying signal over the southwestern region, which could result in reductions in rainfall of more than 40 mm per year.
Increase in the frequency of extreme rainfall events (20 mm of rain falling within 24 hours) over eastern parts during the summer months.
Sea level rise and an increase in the frequency and intensity of sea storms, accompanied by increases in wave heights
Increase in the number of high fire danger days over north-eastern region and along the Cape south coast and the south-western Cape.
Download Data
Climate Change Maps
Projected change in temperature and rainfall over South Africa obtained from a set of dynamical downscalings conducted by the CSIR - NRE. The change in each variable is expressed as an anomaly, the difference between the average climate over a period of the last several decades (1971-2000), and the projected climate (short to medium term 2021 to 2050). The change is based on the median (50th percentile) of the ensemble of six dynamically downscaled GCMs. Changes in climate are based on RCP 4.5 and RCP 8.5.
Determining Future Climate: Global Climate Models
Global climate models, or global circulation models (GCMs), comprise the fundamental tools used for assessing the causes of past change and to project long-term future change (2030–2060). These complex computer models represent interactions between the different components of the climate system, such as the land surface, the atmosphere and the oceans. Projected changes in climate are dependent on the future levels of greenhouse gas emissions in the atmosphere which in turn are crucially dependent on society’s behaviour and policy choices. Global climate models (GCMs) simulate climate under a range of emission scenarios each representing a plausible future. The IPCC Special Report on Emissions Scenarios (SRES) described four possible ‘story lines’ (A1, B1, A2 and B2), each assuming different paths of development for the world. In the IPCC Fifth Assessment Report (AR5), Representative Concentration Pathways (RCPs) replaced the SRES emission scenarios and were used as the basis of the climate projections presented in AR5. The RCP’s are named according to their 2100 radiative forcing level. There are four pathways - RCP2.6, RCP4.5, RCP6.0 and RCP8.5. Whilst RCPs have replaced the SRES emission scenarios in current assessments, the outputs of older SRES GCM simulations and associated downscaled models remain valid.
GCM's have a very coarse resolution (200-300 km) and often cannot capture the physical processes and features of the landscape which are important determinants of local and regional climates. Downscaling techniques translate the changes in the large-scale atmospheric circulation to finer spatial scales. Two main types of downscaling methodologies may be employed, namely statistical (empirical) and dynamical downscaling.